JP6253206B2 - Blade processing apparatus and blade processing method - Google Patents

Description

  The present invention relates to a blade processing apparatus and a blade processing method for processing a blade made of polycrystalline diamond obtained by sintering diamond abrasive grains.

  A dicing apparatus that divides a workpiece such as a wafer on which a semiconductor device or an electronic component is formed into individual chips includes at least a dicing blade that is rotated at high speed by a spindle, a work table on which the work is placed, a work table and a blade X, Y, Z, and θ moving axes that change the relative position of the workpiece are provided, and the workpieces are subjected to cutting processing such as cutting and grooving by the operations of these moving axes.

  Various dicing blades used in such a dicing apparatus have been proposed so far (see, for example, Patent Documents 1 and 2).

  In Patent Literature 1, diamond abrasive grains are bonded to an end surface of a metal base material (aluminum flange) by electroforming using an electroplating technique using a soft metal alloy such as nickel or copper as a binder. A casting blade is described.

  Patent Document 2 describes a diamond blade composed of a substrate composed of a plurality of diamond layers by sequentially laminating diamond layers having different hardnesses by chemical vapor deposition (CVD).

JP 2005-129741 A JP 2010-234597 A

  Incidentally, in recent years, demands for miniaturization and high integration of semiconductor packages are increasing, and semiconductor chips are becoming thinner. Along with this, for example, an ultra-thin workpiece having a thickness of 100 μm or less has been required. Since such an extremely thin workpiece is very easy to break, when dicing an extremely thin workpiece, it is necessary to make the groove width of the cutting groove formed by the dicing blade as small as possible. For example, when a workpiece having a thickness of about 100 μm is cut, the blade thickness of the dicing blade needs to be smaller than the thickness of the workpiece and needs to be at least 100 μm or less. If the cutting process is performed with a dicing blade having a blade thickness larger than the thickness of the workpiece, the workpiece may be broken before being cut. For this reason, for example, when performing grooving processing with a depth of about 30 μm on a workpiece with a thickness of about 50 μm, the width of the groove must naturally be 30 μm or less. It is necessary to keep it below 30 μm.

  However, the conventional dicing blade has the following technical problems, and it is impossible to stably and accurately cut an extremely thin workpiece.

  In addition, for brittle materials, it is difficult to avoid cracks that cause cracks. A ductile material such as copper, aluminum, an organic film, or a resin is not cracked, but has a property of easily generating burrs, and it is difficult to avoid the generation of burrs.

(Problems with cracks due to unadjustable protrusion)
First, in the electroformed blade described in Patent Document 1, as shown in FIG. 21, diamond abrasive grains 92 are scattered in a binder (metal bond) 94, and a diamond having a sharp tip on the surface. The abrasive grains 92 are in a protruding state. At this time, the protruding positions and the protruding amounts of the diamond abrasive grains 92 are varied, and it is difficult in principle to accurately control the protrusion of the abrasive grains. For this reason, the cutting depth in one processing unit cannot be controlled with high accuracy. In particular, when cutting is performed on an extremely thin workpiece having a thickness of 100 μm or less, a crack is generated when the cut exceeds a certain level, and the tip of the diamond abrasive grain gives a fatal cut to the workpiece. May end up. As a result, there is a problem that chipping occurs more or less because the cracks are connected.

  The cause of such a problem is the surface form of the electroformed blade. That is, as shown in FIG. 21, in the electroformed blade, diamond abrasive grains 92 are bonded by a binder 94, but the surface form is such that diamond abrasive grains 92 are scattered in the binder 94. Existing. Therefore, in the electroformed blade, the reference plane 98 that is the overall average height position exists near the surface of the binder 94, and the diamond abrasive grains 92 protrude from the reference plane 98. When the dicing process proceeds in this state, not the diamond abrasive grains 92 but the surface portion of the binding material 94 to which the diamond abrasive grains 92 are connected is reduced, and the protruding amount of the diamond abrasive grains 92 is further increased. For this reason, as described above, it is difficult to accurately control the protruding position and the protruding amount of the diamond abrasive grains 92. In other words, when the depth of cut changes greatly, if a depth of cut greater than the critical depth of cut (Dc value) of the material is entered, a crack is generated, and the ductile mode processing intended by the present invention becomes impossible.

  In particular, in the case of an electroformed blade, as there is a term of self-generated blade, the diamond abrasive grains 92 worn during cutting are dropped off as they are, and then the new diamond abrasive grains 92 underneath act. However, if such diamond abrasive grains 92 are allowed to fall off, the dropped diamond abrasive grains 92 enter between the blade and the workpiece, and consequently promote cracks. In machining with a blade on the premise that diamond falls off, it is impossible in principle to prevent the occurrence of cracks.

(Problems difficult to sharpen)
Also, in the case of electroformed blades, even if you try to machine the blade tip thinly and sharply by machining, diamond abrasive grains exist sparsely, so even if you try to machine thinly or taper Since the diamond abrasive grains fall off from the surface along with the processing, there is a limit to sharpening the blade tip.

  In other words, in order to manufacture a thin blade, when performing electrodeposition plating, a thin plate that is uniformly thin is manufactured and removed from the base material to form a blade. It is difficult to form and thin by processing.

(Heat accumulation problem due to poor thermal conductivity)
In addition, the electroformed blade has poor thermal conductivity, and heat is likely to be accumulated in the blade due to heat generated by frictional resistance with the groove side surface during cutting, which may cause warpage of the blade.

  When the electroformed blade is manufactured using nickel as a binder, as shown in Table 1, the thermal conductivity of nickel is at most about 92 W / m · K. Even when copper is used as a binder, it has only a thermal conductivity of about 398 W / m · K. In this way, if the blade has poor thermal conductivity, heat is likely to accumulate, and the blade may warp or diamond may be graphitized due to heat generated during processing, so cooling and processing with pure water is performed. There are many cases. The thermal conductivity of diamond is 2100 W / m · K, which is orders of magnitude higher than that of nickel and copper.

(Problem that cannot form arbitrary equally spaced cutting edges)
On the other hand, the diamond blade described in Patent Document 2 has the following problems.

  First, since the diamond blade is formed by a CVD method, the blade is formed by a very dense film. As a result, the surface of the diamond blade is almost flat and arbitrarily cut. Therefore, it is impossible to form a recess shape or a pocket for removing chips. Even if fine irregularities are formed as a result, the grain boundary size cannot be arbitrarily set before film formation. Therefore, it is not possible to arbitrarily design the uneven pitch.

(Problems of runout accuracy in blade production by CVD film formation)
When a diamond blade is manufactured by the CVD method, the blade thickness distribution of the blade is determined by the film formation distribution. In particular, when there is a undulation in the film formation distribution, the undulation cannot be removed. That is, even if it is going to remove a wave | undulation by machining, a crack will enter etc. and it is difficult to shape | mold a thin blade. Therefore, it is theoretically difficult to improve the runout accuracy by attaching the reference surfaces to the spindle flange with high precision and no runout.

(Securing flatness by joining dissimilar materials)
In order to reduce the groove width of the cutting groove by the blade, it is preferable that the outer peripheral portion (tip portion) of the blade is as thin as possible. However, the portion that contacts the flange is warped to maintain a highly accurate reference plane. A thickness that does not occur is required. However, when the blade is manufactured as a single piece, if the blade has such portions having different thicknesses, it cannot be manufactured as a single piece by the film forming method, which is substantially impossible. For this reason, joining different types of materials deforms due to thermal stress and disturbs the roundness and flatness, so that it is possible to realize ductile mode processing as in the present invention described later. It can be difficult. Here, when grinding or cutting, when a workpiece is processed in a state where spiral or streamlined chips are produced, it is called ductile mode processing. In other words, ductile mode machining is a process in which removal processing proceeds in a plastic deformation region before brittle fracture of a workpiece material without cracking the workpiece.

  In addition, the configuration in which a diamond chip with a high hardness is embedded in the outer periphery of the blade has different thermal expansion and thermal conductivity between the diamond portion and the base material portion. It becomes difficult to surface the tip heights of minutely different diamond tips on the same plane. In addition, when the chips are arranged in a circumferential shape, the temperature distribution does not become an axisymmetric clean temperature distribution, so that the flatness is also deteriorated due to thermal stress.

  In addition, in order to achieve crack-free ductile mode dicing, it is necessary to limit the grooving or cutting width to a very local region with a thin blade of 0.1 mm or less, but with a configuration in which a diamond tip and a base material are bonded together Such a thin blade cannot be formed. It is difficult to ensure continuous flatness of the diamond tip portion and other base material portions.

  Furthermore, although the diamond tip portion has extremely high hardness, the base material portion may absorb the impact received by the diamond tip due to the elastic effect of the metal portion of the base material. When processing in ductile mode, it is necessary to continuously make a very small cut, but if the base material absorbs such an impact, it is not possible to perform ductile mode processing under a very small cut. Can not.

  From the above, in light of the points of heat conduction, the shape flatness and continuity of the plane, and the point of giving effective shear force locally without absorbing the impact of processing, the blade that embeds the diamond tip is , It becomes a problem.

(In the film formation method, the stress distribution varies depending on the film deposition direction and blade warpage occurs.)
Further, in the above diamond blade, a compressive stress is formed in a film made of a diamond layer formed by the CVD method, so that the stress is applied differently as the film is deposited. For this reason, when the film is finally peeled to form a blade, there is a difference in how the compressive stress is applied on both the left and right sides, resulting in a significant warpage of the blade. Even if the blade warp is corrected, there is no means to correct it, and there is a concern that the yield may deteriorate due to the stress of the film.

  Further, in the blade, it is necessary to provide a cutting edge on the outer periphery. The cutting edge needs some arbitrary continuous unevenness. Even if a uniform sharp blade with no irregularities on the outer periphery is formed like a sharp knife, while removing fine chips while making fine cuts in materials such as brittle materials and in some cases ductile materials In order to solve the problem of the present invention that the processing is advanced, it is impossible to perform substantial cutting without fine irregularities on the outer peripheral portion.

(Scribing problem)
Also, as another problem, it is not a problem of the blade itself, but it is an ideal blade, even if the blade is manufactured accurately, the tip is sharp, and the plane state does not change due to heat during cutting Even if it can be manufactured, how to use the blade is also important. In particular, in the case of scribing, etc., in which the blade itself is pressed against the workpiece in the vertical direction to make a crack and cut, the processing is obviously performed using brittle fracture. Can not do.

  In scribing, the relative speed is set to zero so that the workpiece and the blade do not slip. As a blade configuration, in the case of scribing, the blade needs to rotate freely in order to apply a vertical stress to the material, and the bearing or shaft portion in the blade is pressed vertically downward.

  The blade holding portion for sliding the blade along the workpiece and the blade portion rotating in contact with the workpiece must not be completely fixed. There is no play at all with respect to the blade and it is not directly connected to the motor.

  For this reason, in the conventional scribing blade configuration, the sliding portion between the shaft and the bearing portion is important.

  Incidentally, since the present invention is not a scribing, the motor and the blade are directly connected to each other, and there is no relationship between the shaft and the bearing.

  For this purpose, it is important to align the blade end surface with the flange end surface directly connected to the motor. In other words, the dicing blade requires a reference plane for matching with the flange end face.

(Cutting while maintaining a constant depth of cut for the workpiece)
In addition, the removal volume changes greatly as it is cut, and the volume itself that one cutting edge removes changes. As a result, the predetermined critical cutting depth for removing one cutting edge cannot be controlled, As a result, the cutting resistance may change greatly during the cutting process, and cracks may occur in the workpiece material due to the unbalance. Even in such a case, it causes brittle fracture, and ductile mode machining cannot be realized. That is, in order to maintain a constant cutting depth by one cutting edge microscopically with respect to the workpiece, it is necessary to give a constant cutting to the workpiece to ensure a steady state during machining.

  Moreover, when a workpiece | work is not a flat sample, a workpiece | work cannot be fixed successfully. For example, when a cylindrical workpiece is cut as it is, the workpiece moves and the cut is not constant, and the workpiece may vibrate due to cutting.

  On the other hand, recently, there is a material in which a ductile material and a brittle material are mixed, such as a Cu / Low-k material (a material in which a copper material and a low dielectric constant material are mixed). In brittle materials such as low-k materials, the workpiece must be machined within the deformation zone of the material so as not to cause brittle fracture. On the other hand, since Cu is a ductile material, it does not crack. However, these materials tend to be very elongated while not cracking. Such a highly ductile material clings to the blade and generates a large burr at the part where the blade comes off. In many cases, circular blades form a burr like a beard on the top.

  In addition, when a material having high ductility is dragged by a blade even if it is cut, there is a problem of clinging to the blade. When clinging to the blade, clogging of the blade is accelerated, and the cutting edge portion of the blade is covered with the work material, resulting in a problem that the grinding ability is remarkably lowered.

  The present invention has been made in view of such circumstances, and it is possible to stably and accurately perform a cutting process in a ductile mode without generating a crack or a crack even on a workpiece made of a brittle material. An object of the present invention is to provide a blade processing apparatus and a blade processing method capable of performing the above.

  In order to achieve the above object, a blade processing apparatus according to an aspect of the present invention processes a drive blade composed of polycrystalline diamond obtained by sintering diamond abrasive grains in order to process a workpiece in a ductile mode. It is a blade processing device to be applied, comprising cutting edge generating means for generating a cutting edge by removing the surface of the polycrystalline diamond by electromachining.

  According to this aspect, since the cutting blade generating means for generating the cutting edge by removing the surface of the polycrystalline diamond by electromachining is provided, the cutting edge can be generated on the surface of the polycrystalline diamond. As a result, it is possible to stably and accurately perform a cutting process in a ductile mode without causing cracks or cracks even on a workpiece made of a brittle material.

  Note that even on the surface of polycrystalline diamond, the diamond abrasive grain part is a single crystal because it is a single crystal, but the part of the crystal grain boundary connecting the diamond abrasive grain and the diamond abrasive grain is a trace amount of sintering aid. This is also a place where electric field concentration is likely to occur, because it has a relatively conductive property and is a geometrically discontinuous shape portion compared to the diamond abrasive grain portion. Therefore, unlike ordinary metal plating or the like, the electric field concentrates only on the crystal grain boundary part, and locally high-density electric energy acts on the crystal grain boundary part unlike electric discharge machining. As a result, the erosion action proceeds by local removal processing, and as a result, a sharp cutting edge is formed.

  In the blade processing apparatus according to one aspect of the present invention, the cutting edge generating means may perform electrical machining offline before, during, or during the machining of the workpiece, or in-process electrical machining while machining the workpiece with the driving blade. May be performed. According to the in-process mode, the workpiece is processed while a new cutting edge is always generated on the surface of the polycrystalline diamond, so that it is possible to improve the processing efficiency and the processing accuracy.

  However, even when off-line electrical machining is performed, the same rotating shaft (spindle) is used when machining the workpiece with the drive blade and when machining the drive blade itself to generate a new cutting edge on the drive blade. It is desirable that each processing is performed in a state where the drive blade is attached to the.

  When each process is performed with the drive blades attached to different rotary shafts, even if a new cutting edge is formed on the drive blade, the drive blade is applied to the rotary shaft at the stage of application to the workpiece processing. Installation error occurs. Since this attachment error causes eccentricity during rotation, a constant minute cut is not given to the workpiece, and sometimes a fatal crack is caused to the workpiece. For this reason, the rotating shaft to which the driving blade is attached when machining the workpiece and the rotating shaft when causing the driving blade to issue a new cutting edge are the same, that is, each machining is performed on the same rotation. It is desirable.

  Further, in the blade processing apparatus according to one aspect of the present invention, the drive blade is integrally formed in a disk shape, and the cutting edge generating means is continuous with the outer peripheral portion of the drive blade while rotating the drive blade. An embodiment in which a cutting edge is formed is preferable.

  Moreover, the blade processing apparatus which concerns on 1 aspect of this invention WHEREIN: The said cutting edge production | generation means has a preferable aspect which removes the crystal grain boundary part of the surface of the said polycrystalline diamond by electric discharge machining.

  According to this aspect, the grain boundary portion on the surface of the polycrystalline diamond can be selectively removed by melting by electric discharge machining. Therefore, a cutting edge can be generated on the surface of polycrystalline diamond, and even a workpiece made of a brittle material can be stably and accurately cut in a ductile mode without causing cracks or cracks. It becomes possible.

  Further, in polycrystalline diamond sintered with diamond abrasive grains spread, the cutting edges are automatically arranged at substantially equal intervals by selectively removing from the grain boundary portion. Even if one diamond abrasive grain falls off, the diamond abrasive grains adjacent to it immediately function as a cutting edge, so that the cutting edge state at substantially equal intervals is maintained continuously.

  On the other hand, when sparse abrasive grains are hardened with a binder like a conventional grindstone, if one abrasive grain falls off, there will be no abrasive grains immediately after the abrasive grains fall off. , Only the binder. Therefore, the next abrasive will not appear unless the binder is retracted. In this respect, when the cutting edge is formed by selectively eroding the crystal grain boundary, there is basically no binder, and even if it falls off, the side immediately changes to a cutting edge and the cutting edge is cut at a substantially constant interval. The blade is maintained continuously. However, in the conventional grindstone in which the abrasive grains that have been retreated while removing the binder are exposed, such a continuous cutting edge interval cannot be maintained in principle. Therefore, the polycrystalline diamond obtained by sintering the diamond abrasive grains is completely different in terms of controlling the abrasive grain spacing.

  Further, in the blade processing apparatus according to one aspect of the present invention, the cutting edge generating means includes a processing electrode disposed to face the surface of the polycrystalline diamond, and between the polycrystalline diamond and the processing electrode. An embodiment having a voltage application unit that generates a discharge by applying a voltage and a machining liquid supply unit that supplies a machining liquid between the polycrystalline diamond and the machining electrode is preferable.

  This aspect shows one aspect of the cutting edge generating means. The processing electrode is not particularly limited as long as it can generate a discharge with polycrystalline diamond. For example, a strip electrode, a disk electrode, a wire electrode, or the like can be used.

  However, an electrode structure that causes electric field concentration at the blade tip is desirable. In that case, in the case of a disk-shaped drive blade, the electrode is linearly shaped in a shape facing the tip of the arc-shaped blade, or in a disk shape facing the drive blade. It is good to make it the structure made to do.

  Moreover, the blade processing apparatus which concerns on 1 aspect of this invention WHEREIN: The aspect with which the said process liquid supply means supplies ultrapure water as said process liquid is preferable.

  According to this aspect, polycrystalline diamond as a workpiece is also in a state close to a non-conductor, and a large electric field concentration is generated in a part of the crystal grain boundary having some conductivity. As a result, the electric field concentration effect is combined, and the melting of the crystal grain boundary portion of the polycrystalline diamond occurs selectively by electric discharge machining, which contributes to the formation of the cutting edge.

  Moreover, the blade processing apparatus which concerns on 1 aspect of this invention WHEREIN: The aspect with which the said process electrode is comprised with a metal material or a carbon material is preferable.

  Moreover, the blade processing apparatus which concerns on 1 aspect of this invention WHEREIN: The aspect with which the said process liquid supply means supplies with the flowing water of one direction between the said drive blade and the said process electrode is preferable.

  Moreover, the blade processing apparatus which concerns on 1 aspect of this invention WHEREIN: The aspect in which the said cutting blade production | generation means has an adjustment means to change the relative distance between the said polycrystalline diamond and the said process electrode is preferable.

  According to this aspect, since the interval (discharge gap) between the polycrystalline diamond and the machining electrode can be properly maintained, stable electric discharge machining can be performed.

  In particular, when a cutting edge is formed by eroding the grain boundary portion of polycrystalline diamond, polycrystalline diamond is also a nonconductor, and therefore, if the discharge gap is made too large, it can hardly be processed. Therefore, it is preferable that the discharge gap is extremely small, and the discharge machining can be performed stably and efficiently by controlling the discharge gap by the adjusting means.

  In the blade processing apparatus according to one aspect of the present invention, it is preferable that the voltage applying unit applies a voltage in which the polarity between the polycrystalline diamond and the processing electrode is alternately reversed.

  According to this aspect, by subjecting the surface of the polycrystalline diamond to electrical discharge machining while switching the polarity of the machining voltage alternately between positive and negative in the gap formed by the polycrystalline diamond and the machining electrode, an electrode material for the surface of the polycrystalline diamond is obtained. Is repeatedly attached and detached.

  In particular, when ultrapure water is used as the processing liquid, ultrapure water is a non-conductive medium, but a part of the electrode material is eluted, so that metal ions of the electrode material are contained in the medium (ultrapure water). Partially melts and deposits on polycrystalline diamond, which is a nonconductor. Even on polycrystalline diamond, especially at the grain boundary portion, the electric field concentration becomes large, and the electrode material tends to adhere. Thereafter, when the polarity changes, the electrode material adhering to the crystal grain boundary part is detached, and a selective erosion effect is produced by the electric field concentration effect on the crystal grain boundary part of the polycrystalline diamond. Thereby, efficient and local electric discharge machining becomes possible. Note that, as a voltage for alternately inverting the polarity between the polycrystalline diamond and the machining electrode, there are a bipolar pulse voltage and an AC voltage.

  In order to achieve the above object, a blade machining method according to another aspect of the present invention is directed to a driving blade composed of polycrystalline diamond obtained by sintering diamond abrasive grains in order to machine a workpiece in a ductile mode. And a cutting edge generation step of generating a cutting edge by removing the surface of the polycrystalline diamond by electromachining.

  According to this aspect, since the cutting edge generating step for removing the grain boundary portion on the surface of the polycrystalline diamond by electromachining is provided, the cutting edge can be generated on the surface of the polycrystalline diamond. As a result, it is possible to stably and accurately perform a cutting process in a ductile mode without causing cracks or cracks even on a workpiece made of a brittle material.

  The present invention also includes the following technical ideas.

  A dicing apparatus according to an aspect of the present invention is a dicing apparatus for cutting a workpiece, and is configured in a disk shape by a diamond sintered body formed by sintering diamond abrasive grains, and the diamond sintered body is the diamond A dicing blade having an abrasive content of 80 vol% or more (hereinafter also simply referred to as “%”), a rotating mechanism for rotating the dicing blade, and a constant cutting depth in the workpiece by the dicing blade. And a moving mechanism for moving the workpiece relative to the dicing blade.

  In one aspect of the present invention, it is preferable that the dicing blade cuts the workpiece while rotating in the down cut direction.

  The down cut direction refers to a rotation direction in which the cutting edge of the dicing blade cuts into the work surface when the work is moved relative to the dicing blade.

  Further, in one aspect of the present invention, a cutting edge (a minute cutting edge) made of a recess formed on the surface of the diamond sintered body is continuously provided along the circumferential direction on the outer peripheral portion of the dicing blade. It is preferable.

  Since it is composed of a diamond sintered body, it is completely different from a material obtained by electrodeposition of diamond electrodeposited with a binder softer than conventional diamond.

  In the case of the conventional electrodeposited diamond, the diamond protrudes because the binding material recedes as compared with diamond, and as a result, the diamond abrasive grains protrude from the average level line. As a result, an excessive depth of cut occurs in the abrasive grain portion where the protrusion amount is large, and cracks are caused beyond the critical depth of cut inherent to the material.

  On the other hand, in the case of the present invention, the dicing blade is almost composed of diamond, and the recessed portion surrounded by diamond becomes the cutting edge. Therefore, abrasive grains protruding around and retreating are not formed. As a result, the depth of cut does not become excessive, and the recess acts as a cutting edge. Since the flat reference surface is a diamond surface and there are concave portions in some places, basically, the concave portion is processed as a cutting edge.

  In this way, the diamond abrasive grains exist predominantly in the whole, and the cutting edge to be formed is formed in the diamond abrasive grains due to the presence of the sintering aid left diffused between them. It becomes the cutting edge of the dent that was made. As for the content of diamond abrasive grains at this time, as will be described later, only when the diamond abrasive grain content is 80% or more, the empty portion acts as a cutting edge. When the content decreases, the concave portion is not formed in the outer edge formed by the diamond abrasive grains, so the concave and convex portions are almost the same or the convex portion becomes dominant and relatively protrudes. The part is born and does not become a cutting edge that gives a stable cutting depth below a certain level that does not cause a fatal crack to the workpiece.

  The blade according to the present invention is characterized by being composed of sintered diamond. Sintered diamond is manufactured by increasing the temperature and pressure by spreading diamonds with a uniform particle size in advance and adding a small amount of sintering aid. The sintering aid diffuses into the diamond abrasive grains, and as a result, the diamonds are strongly bonded to each other.

  In electrodeposition blades and electroformed blades, diamonds are not tied together. This is a method in which diamond abrasive grains are hardened by hardening diamonds with surrounding metal.

  In the case of sintering, the diamond particles are firmly connected to each other as the sintering aid diffuses into the diamond. The diamond characteristics can be utilized by bonding the diamond particles together. If the diamond content is large in the rigidity, hardness, heat conduction, etc. of diamond, it becomes possible to make use of physical properties almost similar to diamond. This is because diamonds are bonded together.

  Compared with other manufacturing methods such as electroforming blades, diamonds are connected by being fired at a high temperature and high pressure. Such a sintered diamond corresponds to, for example, Compax Diamond (trademark) manufactured by GE. Compaq diamond combines fine particles composed of single crystals with a sintering aid.

  Speaking of the diamond content, natural diamond and artificial diamond naturally have a high diamond content and exist as strong diamonds. Such single crystal diamonds are liable to crack along the rough face when falling off. For example, when all the blades are made of single crystal diamond, even if the blade is formed into a disk shape, if there is a cut surface in a certain direction, it may break into two from the cut surface. Even when diamond wears due to the progress of processing, there is also a problem that wear occurs depending on the plane orientation along the cleavage plane.

  In the case of single crystal diamond, it is impossible to precisely control the wear process in the material, in what units the diamond is worn.

  On the other hand, a member produced by vapor phase growth by CVD like DLC (diamond-like carbon) is also a polycrystal, but the size of the crystal grain boundary cannot be accurately controlled. For this reason, it is impossible to set the degree of uniform wear even when worn from the grain boundary, and it is not possible to strictly control the crystal units and grain boundary units that are worn away by processing. Therefore, it may happen that a large defect is occasionally generated, or that some defects are excessively stressed and cracked greatly.

  On the other hand, PCD (Polycrystalline Diamond) obtained by firing diamond fine particles at high temperature and high pressure is polycrystalline diamond like DLC, but the crystal structure is completely different. In PCD obtained by firing fine particles, the diamond fine particles themselves are single crystals, and are complete crystals with very high hardness. In PCD, in order to bond single crystals, single crystals are combined by mixing a sintering aid. At that time, since the bonding portions are not completely aligned, the whole is bonded not as a single crystal but as a polycrystal. Therefore, there is no crystal orientation dependency even in the wear process, and it has a certain large strength in any direction.

  From the above, in the case of PCD, all structures are polycrystalline because they are not perfect single crystals, but are polycrystalline bodies in which minute single crystals having uniform sizes are densely assembled.

  With this configuration, the initial state can be maintained with high accuracy in terms of the state of the outer peripheral cutting edge and the pitch unit of the outer peripheral cutting edge during the wear process in machining. In the process of abrasion due to dicing, the portion connecting the single crystal and the single crystal is relatively weak in terms of hardness and strength rather than cracking the single crystal itself, so the bond is broken from the grain boundary portion and falls off I will do it.

  In PCD, when the cutting edges are formed, they are worn along the crystal grain boundaries between the single crystals, so that the cutting edges are set at regular intervals. All the irregularities thus formed become cutting edges. In addition, there are also irregular cutting edges due to grain boundaries between natural irregular cutting edges that exist at equal intervals, and all of these are constituted by diamond, and therefore exist as cutting edges.

  As described above, the blade according to the present invention is particularly effective in combination with the PCD configuration and the disk shape. A cutting edge exists on the outer periphery of the disk shape, and reaches the machining point in such a manner that it sequentially acts on the machining point. The cutting edge does not always exist at the machining point during machining, and contributes to machining only by the pole arc while rotating. Therefore, since the machining and cooling are repeated, the tip portion is not excessively heated. As a result, diamond does not react thermochemically and contributes to processing stably.

  Next, the formation of equally spaced cutting edges is an indispensable element for ductile mode dicing, which is the subject of the present invention described later. That is, in the ductile mode dicing, as will be described later, the cutting depth given to the material by one cutting edge is important, and the cutting depth given to the workpiece by one cutting edge is the "cutting edge interval on the outer periphery of the blade" However, it is concerned with the necessary elements. The relationship between the critical depth of cut and the cutting edge interval given to a workpiece by one blade at this point will be described later, but in order to define the critical cutting depth of one blade, it is essential to set a stable cutting edge interval. . In order to set the interval between the cutting edges with high accuracy, PCD in which single crystal abrasive grains having a uniform particle size are sintered and bonded together is suitable.

  As a supplementary note, in the “formation of equally spaced cutting edges” of the present invention, the arrangement of the diamond abrasive grains in the PCD material in the present invention and the arrangement of diamond abrasive grains in other general cases are performed. Differences from conventional blades are described.

  In an electroformed blade, the content of abrasive grains is small. Also in Japanese Patent Application Laid-Open No. 2010-005778 and the like, the content of diamond abrasive grains in the abrasive layer is about 10%. Therefore, it is unlikely that the abrasive content will exceed 70%. Therefore, each abrasive grain exists sparsely. Although it arrange | positions to some extent uniformly, in order to ensure sufficient protrusion of one abrasive grain, an abrasive grain space | interval is also large.

  Japanese Patent No. 3308246 describes a dicing blade for cutting rare earth magnets, which is formed of a composite sintered body of diamond and / or CBN. The content of diamond or CBN is 1 to 70 vol%, more preferably 5 to 50%. When the diamond content exceeds 70%, there is no problem in terms of warping and bending, but it is weak against impact and easily broken.

  Japanese Patent No. 4714453 also discloses a tool for cutting and grooving composite materials such as ceramics, metal, and glass. In a tool produced by firing diamond, it is described that abrasive grains are contained in an amount of 3.5 to 60 vol% in the firing pair. The technical problem here is that the holding power of the abrasive grains is high even if the bond material has a high elastic modulus and high hardness, and it is said that sufficient protrusion of the abrasive grains can always be maintained with the described configuration. It is described that by sufficiently maintaining “abrasive grain protrusion”, the self-generated blade can be effectively maintained to enable high-speed machining.

  In this way, considering the conventional case, neither the electroforming blade nor the diamond sintered body blade is filled with a gap between the abrasive grains. Moreover, there is no idea that the gap between the spread abrasive grains is a cutting edge. In the present invention, in order to work in the ductile mode, as will be described later, a critical cutting depth given by one cutting edge is important, and in order to keep the cutting depth below a certain level, the interval between cutting edges Becomes important. In addition, the cutting blades are not made of isolated and protruding abrasive grains, but diamonds are laid down to form equally spaced cutting edges using the laid recessed portions.

  22A and 22B schematically show the state of the abrasive grain spacing according to the diamond abrasive grain content. In order to form a cutting edge that does not give excessive cutting at a constant abrasive grain interval, it is necessary to spread diamonds closely and remove some abrasive grains continuously and roughen them. . For that purpose, at least 70% or more of the diamond abrasive grain content is required for spreading. On top of that, some diamond must be removed. Sintering with a diamond abrasive content of 80% or more can form a state in which diamonds are spread at least spatially without gaps as shown in FIG. 22A. Naturally, it becomes possible to form a blade having cutting edges at equal intervals. In addition, all the irregularities thus formed act as cutting edges.

  From the above, in order to form equally spaced cutting edges, it is necessary to use a material fired at a high temperature and high pressure after laying abrasive grains at a high density.

  In addition, when the content rate of a diamond abrasive grain is 70% or less like FIG. 22B, it becomes difficult to form an equal-interval cutting edge arbitrarily. This is because when the content is less than 70%, a portion where diamond abrasive grains are rich and a portion where diamond abrasive grains are not inevitably are born, and a portion where diamond abrasive grains are sparse is cut off due to the presence of isolated abrasive grains therein. This is because the distance between the blades may increase. If the distance between the cutting edges is large, or there are sparse parts, for example, if only one diamond abrasive grain protrudes greatly, the exact protrusion amount cannot be set and a fatal crack to the workpiece will occur. The depth of cut will be given.

  In the above-mentioned Japanese Patent No. 4714453, it is preferable that the content of diamond abrasive grains be 70% or less in order to solve the problem of performing high-speed machining under sufficient abrasive grain protrusion. However, the subject of the present invention is to perform crack-free dicing in the ductile mode. Therefore, in order to make the dent portion between the abrasive grains act as a cutting edge and keep the interval between the cutting edges constant, the diamond content should be at least 70%, ideally 80%. It is desirable that there be more.

  Further, the blade in this case is not simply cut with a sharp blade like a cutter. In other words, the tip is not manufactured with a sharp blade and cut on the principle of pinching. It is necessary to remove the workpiece while cutting and make a groove. It is necessary to continuously cut the next blade into the material while discharging chips continuously. Therefore, it is not necessary for the tip to be sharp, but a fine cutting edge is required.

  In the case of such a structure in which diamond is closely packed, a constant cutting edge interval is formed not only by the grain boundary part but also by the natural roughness of the outer peripheral part. Such a cutting edge interval will be shown later as a specific example, but the diamond particle size and the cutting edge interval may be quite different.

  In the case of having a cutting edge interval different from the diamond particle size, the concept of the cutting edge differs from that of a normal electroformed blade. That is, in the conventional blade, since diamond is embedded in the binder, each diamond exists independently, and therefore the size of the cutting edge is the same as the diamond particle size. That is, one diamond forms one cutting edge. In such a configuration, the unit of the self-generated blade is each diamond, that is, corresponds to each cutting edge. The unit of cutting edge and the unit of self-generated blade do not change. For example, when it is necessary to catch on the workpiece to some extent, it is necessary to make the cutting edge larger because the cutting is necessary. However, the self-generated blade also increases the unit of self-generated blade because the abrasive grains fall off accordingly. As a result, the life is extremely shortened.

  From the above, in conventional electroformed blades and the like, the size of the abrasive grains and the size of the cutting edge are the same as the restriction for maintaining the state of the cutting edge.

  On the other hand, in the case of the blade using the sintered diamond of the present invention, small diamonds are bonded to each other. A cutting edge larger than the diamond particle is formed on the outer periphery of a sintered diamond blade formed by bonding diamonds together. Compared to the unit of the cutting edge, the particle diameter of diamond, which is each abrasive grain constituting the sintered body, is as small as about 1 μm.

  When using the blade according to the present invention, each diamond falls off during processing, but the entire cutting edge does not fall off. Also, when falling off, the abrasive grains constituting one cutting edge like an electroformed blade do not fall off, but in the part where diamonds are bonded, some diamonds are missing and fall off Become.

  As a result, in the process of self-generated blades, in the case of the present invention, diamond is peeled off by wear in a region smaller than the size of the cutting edge, and the size of the cutting edge itself does not change greatly. Within one cutting edge, dicing progresses while peeling off very finely. As a result, the size of the cutting edge itself does not change, and on the other hand, the entire cutting edge is not worn out and the sharpness does not deteriorate. The maximum depth of cut per cutting edge is kept within a certain range while being small and partially self-generated. As a result, it is possible to maintain the ductility mode processing and achieve both stable sharpness.

  In another way, in the case of a dresser in which abrasive particles are hardened by electrodeposition with a conventional binder, such as nickel, if one abrasive grain falls off, the removed part becomes a hole. The cutting edge disappears, and the workability corresponding to that portion is lost. Therefore, in order to maintain workability, in order to make the next cutting edge easy to protrude, it must be designed so that the next abrasive grain protrudes by quickly wearing the binder.

  On the other hand, in the configuration of the present invention, the part where the diamond is missing becomes a small dent, and the dent part also exists as a fine cutting edge existing in a large cutting edge as a region surrounded by another diamond abrasive grain, Constructs a micro roughness that triggers the work. That is, the idea of the self-generated blade is completely different from the conventional configuration in that the diamond missing portion becomes the next cutting edge as it is.

  The concept of the cutting edge, the interval, and the critical cutting depth at which one cutting edge cuts are set as dicing conditions by setting a constant blade cutting with a blade that requires a cutting edge on the outer periphery. It is necessary to feed at a feed rate suitable for the workpiece. Therefore, a premise is an apparatus that operates the blade at a constant feed with a constant cut along the surface shape. When the workpiece is a flat surface, it is necessary to set a constant cut parallel to the workpiece surface to be processed and relatively feed the blade.

  Next, by rotating the disk-shaped blades, the cutting edges at the respective outer peripheral ends are subjected to workpiece removal processing at the processing points, and then the shape is cut as it is, so that the blades are naturally cooled. . In particular, since only a small part is in contact with the workpiece, most of the part is cooled in the form of cutting the sky.

  In the case of cutting, the cutting edge keeps in contact with the workpiece. The cutting edge has heat due to friction, and even diamond may be worn away thermochemically. By cutting the blade into a workpiece while standing up, the diamond wear due to thermal influence can be largely avoided.

  In one aspect of the present invention, the diamond sintered body is preferably obtained by sintering the diamond abrasive grains using a soft metal sintering aid.

  By using a soft metal as a sintering aid, the blade becomes conductive. When the blade is not conductive, it is difficult to accurately estimate the outer diameter of the outer peripheral edge of the blade, and it is difficult to accurately estimate the position of the blade tip with respect to the workpiece in consideration of an attachment error due to attachment to the spindle.

  Therefore, the blade uses a conductive blade, and keeps conduction between the conductive blade and the chuck plate that chucks the reference planar substrate, and when the conductive blade comes into contact with the chuck plate, The relative height of the blade and chuck plate can be found.

  In one embodiment of the present invention, the concave portion is preferably constituted by a concave portion formed by wearing or dressing the diamond sintered body.

  In one embodiment of the present invention, the diamond abrasive grains preferably have an average particle size of 25 μm or less.

  Here, in the above-mentioned Patent No. 3308246, a diamond blade for cutting rare earth magnets is described, but it is desirable that the diamond content is 1 to 70 vol% and the average particle diameter of diamond is 1 to 100 μm. Yes. In Example 1, the average particle size of diamond is 150 μm. This is intended to improve the wear resistance of the cored bar with less warping.

  Similarly, in the blade of Japanese Patent No. 3892204, the average particle size of diamond is effective when the average particle size is 10 to 100 μm, but more preferably the average particle size is 40 to 100 μm.

  In Japanese Patent Laid-Open No. 2003-326466, a blade for dicing ceramics, glass, resin, or metal is used, and the average particle size is preferably 0.1 μm to 300 μm.

  Thus, in the conventional blade, a relatively large diamond particle size is appropriate.

  In the present invention, the average particle diameter of the diamond abrasive grains needs to be 25 μm or less in combination with the diamond content.

  In the case of 25 μm or more, the area ratio where diamonds come into contact with each other is remarkably reduced, and a part of the area is connected by sintering.

  In the blade thickness direction, if there is at least a width in which two to three fine particles exist in the thickness direction, it is impossible to form a strong blade itself in which abrasive grains are connected to each other. If it is composed of fine particles of 25 μm or more, the thickness direction must be at least 50 μm. However, in the case of a blade thicker than 50 μm in the thickness direction, the maximum cutting depth that one blade cuts is larger than the Dc value of 0.1 μm in SiC or the like because of the linearity of the existing cutting blade. Therefore, there is a possibility that the ductile mode processing may not be performed minutely, and it is difficult to process the ideal ductile mode, and the probability of causing brittle fracture in principle becomes very large. This point will be described in detail later.

  Therefore, it is desirable that the diamond particle size be 25 μm or less. However, as for the minimum particle size, the present diamond has been tried with a fine diamond of about 0.3 to 0.5 μm, but the ultrafine diamond with a particle size of less than that is unknown.

  In the aspect of the invention, it is preferable that the outer peripheral portion of the dicing blade is configured to be thinner than the inner portion of the outer peripheral portion, and the thickness of the outer peripheral portion of the dicing blade is 50 μm or less. More preferred.

  Here, the outer peripheral portion of the dicing blade refers to the width of the portion entering the work. In the case of ductile mode dicing, the part entering the work may break the work if the blade width is larger than the work thickness. This will be described in detail later.

  Also, in one aspect of the present invention, the rotating mechanism is provided with a metal flange surface perpendicular to a rotating shaft for rotating the dicing blade, and the dicing blade includes a reference plane portion on one side surface, It is preferable that the reference flat portion is fixed to the rotating shaft in a state where the reference flat portion is in contact with the flange surface. In this aspect, it is more preferable that the reference plane portion of the dicing blade is formed in an annular shape centering on the rotation axis.

  A dicing apparatus according to another aspect of the present invention is a dicing apparatus for cutting a workpiece, and is configured in a disk shape by a diamond sintered body formed by sintering diamond abrasive grains. A dicing blade having a diamond abrasive content of 80 vol% or more, a rotating mechanism for rotating the dicing blade, and giving a constant cutting depth to the workpiece by the dicing blade to give fine particles to the dicing blade And a moving mechanism for moving the work relative to the dicing blade.

  A dicing method according to still another aspect of the present invention is a dicing method for cutting a workpiece, wherein the diamond sintered body is constituted by a diamond sintered body formed by sintering diamond abrasive grains, and the diamond sintered body is A step of giving a constant cutting depth to the workpiece while rotating a dicing blade having a diamond abrasive content of 80 vol% or more, and a state where a constant cutting depth is given to the workpiece by the dicing blade And moving the workpiece relative to the dicing blade.

  In still another aspect of the present invention, it is preferable that the dicing blade cuts the workpiece while rotating in the down cut direction.

  In still another aspect of the present invention, a concave portion (a fine cutting edge) formed on the surface of the diamond sintered body is continuously provided along the circumferential direction on the outer peripheral portion of the dicing blade. It is preferable.

  In still another aspect of the present invention, it is preferable that the diamond sintered body is obtained by sintering the diamond abrasive grains using a soft metal sintering aid.

  In still another aspect of the present invention, the diamond abrasive grains preferably have an average particle size of 25 μm or less.

  In still another aspect of the present invention, the outer peripheral portion of the dicing blade is preferably thinner than the inner portion of the outer peripheral portion, and the thickness of the outer peripheral portion of the dicing blade is 50 μm or less. It is more preferable.

  Further, in still another aspect of the present invention, a metal flange surface perpendicular to a rotation shaft for rotating the dicing blade is provided, and the dicing blade includes a reference plane portion on one side surface, and the reference plane portion is provided. It is preferable that the shaft is fixed to the rotating shaft in a state of being in contact with the flange surface. In this aspect, it is more preferable that the reference plane portion of the dicing blade is formed in an annular shape centering on the rotation axis.

  According to the present invention, it becomes possible to perform cutting with a cutting depth of a dicing blade set to a critical cutting depth of a workpiece or less even for a workpiece made of a brittle material, and cracks and cracks are generated. Therefore, the cutting process can be performed stably and accurately in the ductility mode.

Perspective view showing appearance of dicing machine Front view of dicing blade FIG. 2 is a side sectional view showing a section AA in FIG. Enlarged sectional view showing an example of the configuration of the cutting edge part Expanded sectional view showing another example of the configuration of the cutting edge portion Enlarged sectional view showing still another example of the configuration of the cutting edge portion Schematic diagram schematically showing the state of the surface of the diamond sintered body Diagram showing the surface of the workpiece when grooving with a blade with an average particle diameter of 50 μm, and an example of cracks occurring Sectional view showing the dicing blade attached to the spindle The figure which showed the result of the comparative experiment 1 (silicon grooving process) (this embodiment) The figure which showed the result of comparative experiment 1 (silicon grooving processing) (prior art) The figure which showed the result of the comparative experiment 2 (sapphire grooving process) (this embodiment) The figure which showed the result of comparative experiment 2 (sapphire grooving processing) (prior art) The figure which showed the result of the comparative experiment 3 (when the blade thickness is 20 μm) The figure which showed the result of the comparative experiment 3 (when the blade thickness is 50 μm) The figure which showed the result of the comparative experiment 3 (when the blade thickness is 70 μm) The figure which showed the result of comparative experiment 4 (work surface) The figure which showed the result of comparative experiment 4 (work section) The figure which showed the result of comparative experiment 5 (work surface) The figure which showed the result of comparative experiment 5 (work section) The figure which showed the result of the comparative experiment 6 (this embodiment) The figure which showed the result of the comparative experiment 6 (prior art) Explanatory drawing which showed the mode when a dicing process was performed using the blade which has a cutting edge part of a double-sided taper type Diagram showing how burrs and chipping occur Explanatory drawing when geometrically calculating the maximum depth of cut when machining with the blade translated The figure which showed the result which measured the blade outer periphery end with the roughness meter The figure which showed the result which measured the blade outer periphery end with the roughness meter Diagram showing the surface condition of the blade outer edge (blade tip side) Diagram showing the surface condition of the blade outer edge (blade tip) Schematic showing how the blade tip cuts into the workpiece material Explanatory drawing used to explain the thickness of the blade Explanatory drawing used to explain blade thickness (when blade thickness is greater than workpiece thickness) Explanatory drawing used to explain blade thickness (when blade thickness is smaller than workpiece thickness) Schematic showing the surface of the electroformed blade Schematic showing the state of the abrasive grain spacing according to the diamond abrasive content (when the abrasive content is 80% or more) Schematic showing the state of the abrasive grain spacing according to the diamond abrasive content (when the abrasive content is 70% or less) Cross-sectional view of the outer edge of the blade when a cutting edge is formed with a fiber laser (50 μm holes at 100 μm intervals) Front view of fine particle supply mechanism Side view of fine particle supply mechanism Schematic showing a configuration example of a blade processing apparatus according to the first embodiment Schematic which showed the example of a structure of the blade processing apparatus which concerns on 2nd Embodiment. Schematic showing a configuration example of a blade machining apparatus according to the third embodiment Schematic showing a configuration example of a blade processing apparatus according to the fourth embodiment Schematic showing the state when applied to a conventional electroformed blade Schematic showing how diamond abrasive grains are applied to sintered polycrystalline diamond

  Hereinafter, preferred embodiments of a dicing apparatus and a dicing method according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing the appearance of the dicing apparatus. As shown in FIG. 1, the dicing apparatus 10 includes a load port 12 that transfers a cassette containing a plurality of workpieces W to and from an external device, and a conveyance unit that has a suction unit 14 and conveys the workpieces W to each unit. Means 16, imaging means 18 for imaging the surface of the workpiece W, a processing unit 20, a spinner 22 for cleaning and drying the processed workpiece W, and a controller 24 for controlling the operation of each part of the apparatus. ing.

  The processing unit 20 is provided with an air bearing spindle 28 with a built-in high-frequency motor that is disposed so as to face each other and have a blade 26 attached to the tip, and rotates at a predetermined rotational speed and is independent of each other. As a result, index feed in the Y direction and cut feed in the Z direction are performed. In addition, the work table 30 on which the work W is sucked and mounted is configured to be rotatable around the axis in the Z direction, and is configured to be ground and fed in the X direction in the figure by the movement of the X table 32. Yes.

  The work table 30 includes a porous chuck (porous body) that vacuum-sucks the work W using negative pressure. The work W placed on the work table 30 is held and fixed in a state of being vacuum-sucked by a porous chuck (not shown). As a result, the workpiece W, which is a flat sample, is uniformly adsorbed over the entire surface while being flattened by the porous chuck. For this reason, even if a shear stress acts on the workpiece W during dicing, the workpiece W will not be displaced.

  Such a work holding system that vacuum-sucks the entire work leads to the blade constantly giving a constant cutting depth to the work.

  For example, when the workpiece is a sample that is not corrected into a flat plate shape, it is difficult to define the reference surface of the workpiece surface, so it is difficult to set the blade cutting depth from the reference surface. Become. When the cutting depth of a certain blade with respect to the workpiece cannot be set, it becomes impossible to set a critical cutting depth at which one cutting edge constantly gives a stable cutting, and stable ductile mode dicing is difficult.

  If the workpiece is straightened, the reference surface of the workpiece surface can be defined and the blade cutting depth from the reference surface can be set, so the critical cutting depth per cutting edge can be set and stable. Ductile mode dicing can be performed.

  It should be noted that it may be a form that is not vacuum-sucked but is adhered to the entire surface of the hard substrate. Stable ductile mode dicing is possible if the surface can be defined even on a thin substrate with reference to the firmly bonded surface as a whole.

  FIG. 2 is a front view of the dicing blade. FIG. 3 is a side cross-sectional view showing the AA cross section of FIG. 2.

  As shown in FIGS. 2 and 3, the dicing blade (hereinafter simply referred to as “blade”) 26 of the present embodiment is a ring-type blade, and is attached to the spindle 28 of the dicing apparatus 10 at the center thereof. A mounting hole 38 is formed.

  The blade 26 is made of sintered diamond and has a disk shape or a ring shape. If the blade 26 has a concentric shape, the temperature distribution is axisymmetric. If the temperature distribution is axisymmetric with the same material, the shear stress accompanying the Poisson's ratio does not act in the radial direction. Therefore, the outer peripheral end portion maintains an ideal circular shape, and the outer peripheral end is maintained on the same plane, so that it acts on the workpiece in a straight line by rotation.

  The blade 26 is integrally formed in a disk shape by a diamond sintered body (PCD) formed by sintering diamond abrasive grains. This diamond sintered body has a diamond abrasive grain content (diamond content) of 80% or more, and each diamond abrasive grain is bonded to each other by a sintering aid (for example, cobalt or the like).

  The outer peripheral portion of the blade 26 is a portion cut into the workpiece W, and a cutting blade portion 40 formed in a thin blade shape than the inner portion thereof is provided. In this cutting edge portion 40, a cutting edge (a minute cutting edge) made of a minute recess formed on the surface of the diamond sintered body has a minute pitch (along the circumferential direction of the blade outer peripheral end portion (outer peripheral edge portion) 26 a ( For example, 10 μm) is formed continuously.

  In the present embodiment, the thickness (blade thickness) of the cutting edge portion 40 is configured to be at least thinner than the thickness of the workpiece W. For example, when cutting a workpiece W having a thickness of 100 μm, the thickness of the cutting edge portion 40 is preferably 50 μm or less, more preferably 30 μm or less, and further preferably 10 μm or less.

  As a cross-sectional shape of the cutting edge part 40, it may be formed in the taper shape which thickness becomes thin gradually toward the outer side (front end side), and may be formed in the straight shape which has uniform thickness.

  4A to 4C are enlarged cross-sectional views showing a configuration example of the cutting edge portion 40. 4A to 4C correspond to an enlarged portion of portion B in FIG.

The cutting blade portion 40A shown in FIG. 4A is a one-side tapered type (one-piece V type) in which only one side surface portion is processed obliquely in a tapered shape. In this cutting edge portion 40A, for example, the thickness T ₁ of the outermost end portion formed to be the thinnest is 10 μm, and the taper angle θ ₁ of the portion where the side surface portion on one side is processed into a tapered shape is 20 degrees. Note that the inner portion of the blade 26 (excluding an annular portion 36 described later) has a thickness of 1 mm (the same applies to FIGS. 4B and 4C).

The cutting edge portion 40B shown in FIG. 4B is of a double-sided taper type (both V-type) in which the side surfaces on both sides are processed obliquely in a tapered shape. In this cutting edge portion 40B, for example, the thickness T ₂ of the outermost end portion formed to be the thinnest is 10 μm, and the taper angle θ ₂ of the portion where the side surface portions on both sides are processed into a tapered shape is 15 degrees. .

The cutting blade portion 40C shown in FIG. 4C is of a straight type (parallel type) in which the side portions on both sides are processed in parallel in a straight shape. In this cutting edge portion 40C, for example, the thickness T _{3 of the} tip portion processed into the thinnest straight shape is 50 μm. In addition, the inner side portion (center side portion) of the straight tip portion has one side surface portion processed into a taper shape, and the taper angle θ ₃ is 20 degrees.

  FIG. 5 is a schematic view schematically showing a state near the surface of the diamond sintered body. As shown in FIG. 5, the diamond sintered body 80 is in a state in which diamond abrasive grains (diamond particles) 82 are bonded to each other at a high density by the sintering aid 86. On the surface of the diamond sintered body 80, a cutting edge (microscopic cutting edge) 84 composed of a microscopic recess (concave) is formed. The recess 84 is formed by selectively wearing a sintering aid 86 such as cobalt by mechanically processing the diamond sintered body 80. Since the diamond sintered body 80 has a high abrasive density, the dent formed when the sintering aid 86 is worn becomes a minute pocket, and there is no protrusion of sharp diamond abrasive grains like an electroformed blade. (See FIG. 21). For this reason, the dent formed on the surface of the diamond sintered body 80 functions as a pocket for conveying chips generated when the workpiece W is cut, and also functions as a cutting edge 84 that gives a cut to the workpiece W. To do. As a result, the chip discharge performance is improved, and the cutting depth of the blade 26 with respect to the workpiece W can be controlled with high accuracy.

  Here, the blade 26 of the present embodiment will be described in more detail.

  As shown in FIG. 5, the blade 26 of the present embodiment is integrally constituted by a diamond sintered body 80 formed by sintering diamond abrasive grains 82 using a sintering aid 86. For this reason, there is very little sintering aid 86 in the gap between the diamond sintered bodies 80, but the sintering aid is also diffused in the diamond abrasive grains themselves, and in fact, the diamonds are firmly bonded together. It becomes a form to do. Cobalt, nickel, etc. are used for this sintering aid 86, and hardness is low compared with a diamond. Therefore, although the diamonds are bonded to each other, the portion rich in the sintering aid is slightly weaker than the single crystal diamond. Such a portion is worn and reduced when the workpiece W is processed, and becomes an appropriate recess with respect to the surface (reference plane) of the diamond sintered body 80. Further, by subjecting the diamond sintered body 80 to wear processing, a recess from which the sintering aid is removed is formed on the surface of the diamond sintered body 80. In addition, some diamonds are missing in addition to the sintering aid by sharpening with a grinding wheel of GC (Green Carborundum) or by cutting a cemented carbide which is a hard brittle material in some cases. Appropriate roughness is formed on the outer periphery of the diamond sintered body. By setting the roughness of the outer peripheral portion to be larger than the diamond particle size, a minute diamond abrasive grain is lost in one cutting edge, and the cutting edge is hardly worn.

  The dent formed on the surface of the diamond sintered body 80 works advantageously for processing in the ductile mode. In other words, as described above, the dent functions as a pocket for discharging chips generated when the workpiece W is cut, and also functions as a cutting edge 84 that gives a cut to the workpiece W. For this reason, the amount of cut into the workpiece W is naturally limited to a predetermined range, and no fatal cut is given.

  In addition, according to the blade 26 of the present embodiment, since the diamond sintered body 80 is integrally formed, the number, pitch, and width of the recesses formed on the surface of the diamond sintered body 80 are also arbitrarily determined. It becomes possible to adjust.

  That is, the diamond sintered body 80 constituting the blade 26 of the present embodiment is obtained by bonding the diamond abrasive grains 82 to each other using the sintering aid 86. For this reason, there is a sintering aid 86 between the diamond abrasive grains 82 bonded to each other, and a grain boundary exists. Since this grain boundary portion corresponds to a dent, the pitch and number of the dents are naturally determined by setting the particle diameter (average particle diameter) of the diamond abrasive grains 82. Further, by using the sintering aid 86 using a soft metal, selective dent processing can be performed, and the sintering aid 86 can be selectively worn. Further, the roughness can be adjusted by setting the wear process and the dressing process while rotating the blade 26. That is, the pitch, width, depth, and number of the cutting edges 84 formed of dents formed on the surface of the diamond sintered body 80 are determined depending on the pitch of the grain boundaries formed along with the selection of the grain size of the diamond abrasive grains 82. It becomes possible to adjust. The pitch, width, depth, and number of the cutting edges 84 play an important role in performing ductile mode processing.

  As described above, according to the present embodiment, the desired grain size of the diamond abrasive grains 82 is adjusted along the crystal grain boundaries with high precision by appropriately adjusting parameters having good controllability such as wear processing and dressing processing. The spacing of the blades 84 can be achieved. In addition, on the outer peripheral portion of the blade 26, it is possible to arrange the cutting edges 84 formed of dents formed on the surface of the diamond sintered body 80 in a straight line along the circumferential direction.

  Here, as a comparison, there is a wheel used for scribing that is similar to a wheel in which diamond abrasive grains are sintered. However, in order to avoid confusion with the scribing wheel, a difference will be mentioned.

  A wheel used for scribing is disclosed in, for example, Japanese Patent Laid-Open No. 2012-030992. The above document discloses a wheel formed of sintered diamond and having an annular blade having a cutting edge on the outer peripheral portion. Although scribing and dicing according to the present invention are both considered to be in the same category in the technology of dividing the material, the processing principle and the specific configuration are completely different depending on the processing principle.

  First, as a crucial difference between the above document and the present invention, the scribing of the above document refers to a scribing line (longitudinal crack) on the surface of a substrate formed of a brittle material as described in the above paragraph [0020]. ), And vertical cracks extending in the vertical direction are generated by scribing (see paragraph [0022] above). Cleaving using this crack.

  On the other hand, the principle of the present invention is completely different as a processing method for removing material in a shearing manner without generating cracks or chipping. Specifically, since the blade itself rotates at high speed and acts almost horizontally with respect to the workpiece surface to remove the workpiece, no stress is applied in the vertical direction of the workpiece. In addition, since the depth of cut is limited within the deformation region of the material and processing is performed with a depth of cut that does not generate cracks, a crack-free surface is obtained as a result. From the above, the processing principle is completely different.

  In light of the above differences in processing principles, specific differences in blade specifications are listed below.

・ (Point of tip angle)
Since scribing only generates cracks inside the material, it hardly enters the material. Since only the edge line of the cutting edge is applied, the cutting edge angle is usually an obtuse angle (see paragraph [0070] above). A sharp angle of 20 degrees or less cannot be considered at all in consideration of defects caused by twisting.

  On the other hand, dicing penetrates into the material and removes the part that entered, so the edge of the blade is straight or at most the apex angle of the blade is V-shaped to the extent that buckling due to dicing resistance in the blade traveling direction is considered. To some extent. The maximum apex angle is 20 degrees or less.

  Also, if the apex angle is 20 degrees or more, the cross-section after cutting becomes oblique and the cross-sectional area increases, and in terms of machining mechanism, grinding is performed on the side of the blade rather than the element that the blade tip advances. The volume to be increased. As a result, the processing efficiency decreases, and sometimes the processing does not proceed. In the case of dicing, a cutting edge is formed on the outer periphery of the blade and the cutting edge at the tip is efficiently advanced, while the blade side surface is mirror-finished while improving the lubricity with the workpiece and reducing the amount of grinding. Is required. When the amount of grinding on the side surface of the blade increases, the grinding amount on the side surface inevitably increases, and the cross section after cutting cannot be mirror-finished. Therefore, a straight shape is most desirable for dicing, but it is preferable that the shape is extremely small and V-shaped so that the blade does not buckle at least, and it is 20 degrees or less at most.

・ (Points of material composition)
In scribing, if the traveling direction changes in a state where the wheel is in contact with the workpiece (a state where the wheel is bitten), the cutting edge may be lost due to torsional stress. Therefore, even if it is the same sintered body of diamond, the weight percentage of diamond is set to 65% to 75%. As a result, not only wear resistance and impact resistance but also torsional strength characteristics are improved. If the weight percentage of diamond is 75% or more, the hardness of the wheel itself is increased, but the torsional strength is decreased. Therefore, the diamond content is set to be relatively small.

  On the other hand, dicing proceeds linearly while the blade rotates at a high speed to remove a certain amount of material. Therefore, no torsional stress is applied. Instead, if the diamond content is low, the apparent hardness will drop when cutting, so the reaction force from the workpiece and the workpiece will elastically recover within the time when the blade cutting edge is cut, The predetermined depth of cut may not be maintained. For this reason, in the case of dicing, the hardness of the blade is sufficiently larger than the hardness of the workpiece so that the blade does not rebound and can be cut with a predetermined cut. In the ductile mode, the surface hardness equivalent to that of single-crystal diamond (about 10000 Knoop hardness) is required to allow machining to proceed without allowing elastic recovery within the cutting edge working time during machining within the deformation range of the material. About 8000 in hardness is required. As a result, the diamond content needs to be 80% or more. However, when the diamond content is 98% or more, the ratio of the sintering aid is extremely reduced, so that the bonding force between the diamonds is weakened, the toughness of the blade itself is lowered, and it becomes brittle and easily chipped. Therefore, the diamond content needs to be 80% or more, and considering the practical point, it is desirable to make it 98% or less.

  From the above, even if the PCD used for the scribing wheel and the PCD used for the dicing blade of the present invention are the same material, the processing principle is completely different, so the required PCD composition, specifically, The diamond content is quite different.

・ (Points of wheel structure and reference surface)
Furthermore, the structure of the wheel is different. The scribing wheel has a holder, and the holder is an element that rotatably holds the scribing wheel. Since the holder mainly has a pin and a support frame, the pin portion (shaft portion) does not rotate. The inner diameter part of the wheel becomes a bearing and rotates by rubbing relatively with the pin part that is the shaft, thereby forming a vertical scribing line (longitudinal crack) on the material surface.

  On the other hand, in the blade according to the present invention, the blade is coaxially attached to the rotating spindle. The spindle and blade are integrally rotated at a high speed. The blade needs to be mounted perpendicular to the spindle axis, and it is necessary to eliminate runout due to rotation.

  Therefore, the blade has a reference plane. The reference surface existing on the blade is fixed in contact with a reference end surface of a flange previously attached to the spindle in a vertical direction. Thereby, the perpendicularity with respect to the spindle rotation axis of the blade is ensured. Only when this perpendicularity is secured, the cutting blade formed on the outer peripheral portion acts on the workpiece in a straight line when the blade rotates.

  In addition, the reference surface in the case of scribing is a cylindrical surface parallel to the axis of the disk blade, and is defined on the assumption that the blade is pressed vertically. However, the reference plane of the blade in the blade according to the present invention is the side end face (disk surface) of the blade facing the flange of the spindle as described above. By setting the reference surface of the blade to the side surface (disk surface) of the blade, the blade rotates with high precision in a balanced state with respect to the blade center. Therefore, the cutting edge formed at the tip of the blade operates accurately at a predetermined height defined by a fixed radial position with respect to the center of the blade, even if the blade rotates at a high speed. The vertical cutting edge acts on the workpiece surface horizontally without giving a vertical stress to the workpiece. Therefore, even if the workpiece is a brittle material, there is no crack at all on the workpiece surface due to normal stress.

・ (Processing principle)
The difference in principle between scribing and dicing according to the present invention is whether the processing is performed with cracks in the vertical direction or processing without generating any cracks.

・ (Role of groove of outer peripheral blade)
In addition, the scribing is applied only to the surface by the vertical stress of the scriber to form a scribing line. The role of the groove of the outer peripheral blade in the case of scribing is to generate a crack perpendicular to the material while the protrusion of the wheel blade edge is in contact with the brittle material substrate (the above paragraph [0114] ]reference). That is, the groove other than the groove can be provided with a scribing line that can penetrate the material and cause vertical cracks. Therefore, it is more important how the crest portion between the grooves bites into the material rather than the groove.

  On the other hand, in the case of dicing, the recess provided in the outer peripheral end plays the role of a cutting edge. A portion between the recesses is set so as to form a contour of the outer periphery and to have a critical depth of cut so that a cutting edge provided therebetween does not crack the work surface. Therefore, in the case of dicing, it is necessary to form a cutting edge.

  In addition, the groove depth in the case of scribing is formed so as to give the amount of biting for attaching the scribing line, but in the case of dicing, the groove depth enters the work and the work piece is cut with each cutting edge. Must be removed by grinding. For this reason, the blade tip completely enters the workpiece, but the blade is not allowed to sway, and the cutting edge must act perpendicularly to the workpiece surface deeply into the material.

  In the case of the blade according to the present invention, the outer peripheral end portion has concave cutting edges with a constant interval. As will be described later, it is sufficient that the critical cutting depth given by one cutting edge does not cause cracks. For this purpose, it is necessary to keep the cutting edge distance appropriate.

  In the scribing wheel, the direction of the cutting edge of the scribing wheel is changed by 90 degrees while the scribing hole is in contact with the brittle material, which is called a caster effect.

  In the dicing blade, the blade is in the material, so the direction of the blade cannot be changed by 90 degrees. For example, if the cutting edge is changed while abutting with a dicing blade having a straight shape or an apex angle of 20 degrees or less, the blade breaks.

  In the case of the diamond sintered body 80 sintered using the sintering aid 86 made of a soft metal, wear treatment and dressing treatment are the most suitable methods for forming a dent on the surface. Not limited to. For example, when a sintering aid such as cobalt or nickel is used, it is possible to form a dent on the surface of the diamond sintered body 80 by chemically partial dissolution by acid-based etching.

  In contrast, in conventional electroformed blades, the diamond abrasive grains themselves act as cutting edges, but in order to adjust the pitch and width of the cutting edges, the degree of dispersion in which the diamond abrasive grains are initially dispersed It is technically difficult to rely on. That is, there is a lot of ambiguity of dispersion of diamond abrasive grains and it cannot be controlled substantially. Moreover, even if there are portions where the diamond abrasive grains are not sufficiently dispersed and agglomerated, or there are portions where the diamond abrasive grains are too dispersed and sparse, it is difficult to arbitrarily adjust this. As described above, it is impossible to control the arrangement of the cutting edges with the conventional electroformed blade.

  In addition, with conventional electroforming blades, it is not possible to artificially arrange micron-order diamond abrasive particles one by one, and it is almost impossible to efficiently align the cutting edges in a straight line. Impossible. In addition, it is difficult to control the amount of cut with respect to the workpiece W with a conventional electroformed blade in which the dense and sparse portions of the cutting blades are mixed and the arrangement of the cutting blades cannot be substantially controlled. The mode cannot be processed.

  In the blade 26 of the present embodiment, the average particle diameter of the diamond abrasive grains contained in the diamond sintered body is preferably 25 μm or less (more preferably 10 μm or less, and further preferably 5 μm or less).

  According to the results of experiments conducted by the present inventor, when the average particle diameter of diamond abrasive grains was 50 μm, cracks occurred when the wafer material was SiC and was diced with a cutting depth of 0.1 mm. This is probably due to diamonds falling off. When sintered with a diamond average particle size of 50 μm or more, the area where the diamond particles are in close contact with each other is reduced, and large particles are bonded with a local area. For this reason, the material composition has a drawback that it is very weak in impact resistance and is easily chipped. When diamond falls off in units of 50 μm or more due to local impact, a very large cutting edge is formed as a result of the falling off. In this case, a cutting depth greater than a predetermined critical cutting depth is given as an isolated cutting edge, and as a result, the occurrence of chipping and cracking is extremely high. In addition, when a diamond of about 50 μm falls off, not only the remaining cutting edge becomes large, but also the dropped diamond abrasive grains themselves are entangled between the workpiece and the blade and may cause further cracks. . If the particle size is 25 μm or less, such a crack has not been obtained.

  FIG. 6 shows the surface of the workpiece when grooving is performed with a blade having an average particle diameter of diamond abrasive grains of 50 μm, and shows an example in which cracks are generated.

  Table 2 shows the results of evaluating the incidence of cracking or chipping when grooving with a blade with an average particle size of 50, 25, 10, 5, 5, or 0.5 μm. Show. The evaluation results indicate that the occurrence rate of cracks or chipping increases in the order of A, B, C, and D. Other conditions are as follows.

Standard evaluation conditions: SiC substrate (4H) (hexagonal crystal)
・ Spindle speed: 20000rpm
・ Feeding speed: 1mm / s
・ Depth of cut: 100μm
・ Evaluation guidelines: Evaluate whether there is chipping of 10μm or more. (Ideally there should be no chipping.)

  In sapphire, cracks occurred at a depth of 0.2 μm. Quartz and silicon were also cracked with similar cuts.

  Furthermore, when the average particle diameter of the diamond abrasive grains is 50 μm, it is difficult to reduce the blade thickness (the thickness of the outer peripheral edge of the blade) to 50 μm or less, and the blade 26 is chipped at the outer peripheral portion of the blade 26 when manufacturing the blade 26. There are many. Also, even if you try to manufacture a blade with a blade thickness of 100μm (0.1mm), there is a part with a large gap, and it may be cracked by a slight impact, so it is realistic to manufacture the blade stably. Was difficult.

  On the other hand, when the average particle diameter of the diamond abrasive grains is 25 μm, 5 μm, 1 μm, and 0.5 μm, each brittle material of SiC, sapphire, quartz, and silicon is cut in the same way as when the average particle diameter is 50 μm. However, no cracks occurred. That is, in these brittle materials, when the average particle diameter of the diamond abrasive grains is 50 μm, cracks are generated by cutting in the order of submicron, and when diamond abrasive grains having an average particle diameter larger than that are used, the cutting is necessarily performed. Will increase and lead to fatal cracks. On the other hand, when diamond abrasive grains having an average particle diameter of 25 μm or less (more preferably 10 μm or less, and even more preferably 5 μm or less) are used, the cutting can be suppressed to be small and the cutting depth can be controlled with high accuracy. Is possible.

  The general processing conditions of this experiment are a blade outer diameter of 50.8 mm, a wafer size of 2 inches, a notch 10 μm grooving, a spindle rotation speed of 20,000 rpm, and a table feed speed of 5 mm / s.

  As a manufacturing method of the blade 26 configured as described above, diamond fine powder is placed on a base mainly composed of tungsten carbide and put in a mold. Next, a solvent metal such as cobalt (sintering aid) is added to the mold as a sintering aid. Next, it is fired and sintered in a high pressure of 5 GPa or higher and a high temperature atmosphere of 1300 ° C. or higher. Thereby, diamond abrasive grains are directly bonded to each other, and a very strong diamond ingot is formed. In this way, for example, a cylindrical ingot having a diameter of 60 mm, a sintered diamond layer (diamond sintered body) of 0.5 mm, and a tungsten carbide layer of 3 mm can be obtained. Examples of the diamond sintered body formed on tungsten carbide include DA200 manufactured by Sumitomo Electric Hardmetal Corporation. The blade 26 of this embodiment can be obtained by taking out only the diamond sintered body and subjecting the blade base material to a predetermined shape and subjecting it to peripheral wear or dressing. In addition, the diamond surface of the cylindrical ingot (excluding the cutting edge portion 40) is subjected to surface roughness (arithmetic average roughness) by performing skiff polishing (scaif, a polishing disk) as a reference surface formation for eliminating vibration during rotation. Ra) It is preferable to process a mirror surface of about 0.1 μm.

  Here, the abrasion treatment / dressing treatment in the above production method can be performed under the following conditions.

  The wear process includes the following conditions.

・ Blade rotation speed: 10000rpm
・ Feeding speed: 5mm / s
-Workpiece processing target: Quartz glass (glass material)
-Processing time: 30 minutes-By the said process, the cobalt sintering auxiliary agent of about 1-2 micrometers was removed slightly, and the dent was formed. Furthermore, the dent became deeper by applying a very thin etching solution (weak acid type) thinly and processing it in a dry environment without supplying pure water.

  The following conditions may be used as a dressing process (abrasion process).

・ Blade rotation speed: 10000rpm
・ Feeding speed: 5mm / s
・ Workpiece object: GC600 dressing wheel (70mm □)
(GC600 means that the particle size of the silicon carbide abrasive is 600 (# 600). The particle size is based on Japan Industrial Standards (JIS) R6001)
-Processing time: 15 minutes-Even in this treatment, the cobalt sintering aid was slightly removed and dents were formed.

  Of the blade outer periphery, it is desirable to change the roughness of the blade outer end and the blade side surface. Specifically, the outer peripheral edge of the blade corresponds to a cutting edge, and the cutting edge interval is adjusted along the crystal grain boundary by wear processing. Particularly, the outer peripheral edge of the blade is slightly roughened since it is removed by machining to a certain extent while cutting the workpiece material.

  On the other hand, the blade side surface portion is not actively removed, but may be rough enough to cut out the groove side surface portion when contacting the groove side surface portion of the workpiece material. In addition, if there are protrusions on the blade side surface, cracks will be induced in the groove side surface portion, so that processing is performed without forming the protrusion portion, while the contact area with the groove side surface portion is reduced, and even a little friction occurs. It is necessary to reduce the heat generation due to. Therefore, it is desirable that the side surface portion is finely roughened.

  In conventional electroformed blades, etc., the abrasive grains are solidified by plating, so that the entire surface has the same abrasive grain distribution, and as a result, the form of how the abrasive grains are attached to the blade outer peripheral edge and the blade side surface. I could not divide it. That is, the roughness condition could not be clearly changed between the outer peripheral edge of the blade for advancing the workpiece and the side portion that is finely scraped while rubbing against the workpiece.

  In the case of the blade according to the present invention, most of the blade is composed of diamond and can be molded from that state. For example, in the case of the blade according to the present invention, diamond wrapping or the like may be performed in order to roughen the side surface portion. By roughening the surface with fine diamond (particle size: 1 μm to 150 μm), it is possible to form a roughness with Ra of about 0.1 μm to 20 μm, for example.

  On the other hand, unlike the blade side surface portion, the blade outer peripheral portion needs to be cut while machining the workpiece. Therefore, unlike the side surface portion, it is better to have roughness as a cutting edge. Such roughness can be formed on the outer periphery with a pulse laser, for example.

  When the cutting edge is formed with a pulse laser, the following conditions are preferably used.

Laser oscillator: Fiber laser manufactured by IPG, USA: YLR-150-1500-QC
W
Feeding table: JK702
Wavelength: 1060nm
Output: 250W
Pulse width: 0.2msec
Focal position 0.1mm
Blade rotation speed 2.8rpm
Gas: High purity nitrogen gas 0.1L / min
Hole diameter 50μm
Blade material: Sumitomo Electric DA150 (diamond particle size 5μm)
Outer diameter 50.8mm
With such a pulsed fiber laser, as shown in FIG. 23, a semicircular sharp cutting edge continuous at a constant interval of 0.05 mm in diameter can be formed on the outer peripheral edge of the blade at a pitch of 0.1 mm. In such cutting edge formation, the diamond particle size is 5 μm, but one cutting edge itself can be a 50 μm cutting edge. If these are formed at equal intervals, the apparent interval is reduced by increasing the number of rotations, and dicing in the ductile mode becomes possible. (Example: When the spindle speed is 10,000 rpm or more)
With fiber lasers, the size of a single cutting edge can be formed with various hole diameters, from a size of about 5 μm to 1 mm with a large one. It is possible to open up to about 200μm.

  Rather than forming a notch with a diamond-hardened material such as an electroforming method, it is made of sintered diamond material and a small notch is continuously formed at the outer periphery of the disk. Each notch acts as a cutting edge.

  Japanese Unexamined Patent Publication No. 2005-129741 describes a method of forming a notch in the outer peripheral portion of a blade manufactured by an electroforming method. In this case, the notch prevents a chip discharge function and clogging. Notches are provided as a function, not as cutting edges. When manufactured by electroforming, diamond is not necessarily present at the edge of the notch, but is present together with the binding material, so that the binding material wears with processing, and thus acts as a cutting edge as a material. It is not a thing.

  On the other hand, when the blade is composed of a diamond sintered body, the tip of the cutting edge opened in the outer peripheral portion acts as it is as a cutting edge. In addition, since the diamond abrasive grain size is as small as 5 μm compared to the size of the cutting edge of 50 μm, one diamond abrasive grain is chipped off in one cutting edge, and it is possible to grow smaller in the cutting edge. Become. In the conventional electroforming method, since the diamond abrasive grains act as a cutting edge as they are, the size of the cutting edge and the self-generated unit are the same size, but in the case of the present invention, an arbitrary cutting edge is formed. Thus, the size of the cutting edge and the unit in which the diamond grows can be changed, and as a result, the sharpness can be secured for a long time.

  Furthermore, by increasing the roughness of the outer peripheral edge of the blade relative to the roughness of the blade side surface, the blade side surface can be mirror-finished while cutting the workpiece with a fine rough surface while cutting at the blade outer peripheral edge. Can do. Conventionally, with an electroforming blade, it was difficult to change the roughness of the outer peripheral edge and the roughness of the side surface independently, and this could not be substantially achieved. Thus, it is possible to form equally spaced cutting edges at the outer peripheral end and to make the blade side surface fine and rough. As a result, it is possible to perform mirror finishing independently of the workpiece side surface, while ensuring efficient cutting of the outer periphery and proceeding efficiently.

  In addition, a configuration (for example, JP-A-7-276137, etc.) in which high-hardness diamond chips are embedded one by one only on the outer periphery of the blade, the cutting edges may be formed at equal intervals. Since it is not formed by PCD, as described above, it gives local effective shearing force to the workpiece without absorbing the impact of heat conduction, shape flatness and plane continuity, and impact due to processing. It is obvious that the blade is completely different from the blade according to the present invention in that the processing is performed in the ductile mode.

  The distance between the cutting edges and the surface roughness of the side surface are appropriately adjusted according to the material to be processed.

  FIG. 7 is a cross-sectional view showing a state in which the blade 26 is attached to the spindle 28. As shown in FIG. 7, the spindle 28 is supported by a spindle main body 44 incorporating a motor (high-frequency motor) (not shown), and is pivotally supported by the spindle main body 44, and its tip protrudes from the spindle main body 44. And a spindle shaft 46 disposed on the main body.

  The hub flange 48 is a member interposed between the spindle shaft 46 and the blade 26, and is provided with a mounting hole 48a formed in a tapered shape and a cylindrical projection 48b. The hub flange 48 is provided with a flange surface 48c serving as a reference surface for determining the perpendicularity of the blade 26 to the spindle shaft 46 (rotation shaft). A blade reference surface 36a of the blade 26 is brought into contact with the flange surface 48c as will be described later.

  The blade 26 is provided with an annular portion (contact region) 36 formed thick on the inner side of the cutting edge portion 40 on one end face (see FIGS. 2 and 3). The annular portion 36 is formed with a blade reference surface 36a with which the flange surface 48c of the hub flange 48 abuts. The blade reference surface 36a is preferably provided at a higher position than the other positions on the end surface where the annular portion 36 is formed, thereby facilitating flatness. Further, the thickness of the annular portion 36 constituting the blade reference surface 36a needs to be sufficiently thicker than that of the cutting edge portion 40 provided on the outer peripheral portion of the blade.

  Since the blade outer peripheral portion does not cause brittle fracture on the material surface at the time of cutting, it is necessary to reduce the cutting width, and the thickness must be 50 μm or less.

  However, when manufacturing everything including the blade reference surface portion with the thickness of the outer peripheral portion of the blade with a thickness of 50 μm or less, the processing strain at the time of processing in the process of drawing out the flat surface of the blade becomes a big problem. In particular, if the entire surface of the blade is manufactured with a thickness of about 50 μm, the blade warps to one side due to the balance of strains on both sides of the blade. When the blade is warped even a little, the outer peripheral end portion is very thin, so that the blade is buckled and deformed to the side originally warped by a very small stress, and as a result cannot be used.

  For this reason, even if a processing strain remains on the blade surface, the portion that forms the blade reference surface must not have a thickness that causes warping due to the strain. The thickness of the reference surface portion of the blade, which is a disk having a diameter of about 50 mm and does not warp due to processing strain, is at least 0.25 mm, preferably 0.5 mm or more. Without such a thickness of the blade reference surface portion, a flat surface cannot be maintained as the blade reference surface. If the plane cannot be maintained, it becomes difficult to make the outer peripheral edge of the blade act on the workpiece in a straight line.

  From the above, the blade 26 of this embodiment must satisfy the following conditions.

  That is, the blade reference surface 36a must maintain a flat surface even if the balance of the processing strains on both side surfaces of the blade 26 is lost. Therefore, the thickness of the reference surface portion must be at least 0.3 mm.

  On the other hand, the outer peripheral edge of the blade must be processed in a very small region so as not to induce cracks in the material. For that purpose, the thickness of the cutting edge part 40 provided in a blade outer peripheral part needs to be 50 micrometers or less.

  In other words, for example, when looking at the entire blade with a diameter of 50 mm, it is necessary to manufacture everything in one piece to maintain flatness, and the blade inner periphery must be made thicker to maintain flatness, while the blade outer periphery is It must be thinned.

  In addition, as a method for obtaining the flatness, mirror finishing by Skyf polishing or the like can be used.

  As a method of attaching the blade 26, first, the hub flange 48 is positioned on the spindle shaft 46 by a fixing means (not shown) in a state where the tapered spindle shaft 46 is fitted in the attachment hole 48a of the hub flange 48. Fix it. Next, in a state in which the mounting hole 38 of the blade 26 is fitted to the protrusion 48b of the hub flange 48, the blade nut 52 is screwed into a screw portion formed at the tip of the protrusion 48b, whereby the blade 26 is moved to the hub flange 48. Position and fix to.

  Thus, when the blade 26 is attached to the spindle shaft 46 via the hub flange 48, the perpendicularity of the blade 26 with respect to the spindle shaft 46 is such that the flatness of the flange surface 48c of the hub flange 48 and the blade reference surface 36a of the blade 26 are. It is determined by the flatness and the mounting accuracy for superimposing both. For this reason, the flange surface (surface perpendicular to the rotation axis) 48c of the hub flange 48 and the blade reference surface 36a of the blade 26 in contact with the flange surface 48c are flattened by, for example, mirror finishing, and are thus made to the spindle shaft 46. It is preferable that the perpendicularity is formed with high accuracy. Thus, when the blade 26 is mounted on the spindle shaft 46 via the hub flange 48, the blade 26 is positioned with respect to the spindle shaft 46 by positioning and fixing the blade surface 48c and the blade reference surface 36a in contact with each other. Can be perpendicular to accuracy.

  Further, since the accuracy of the center position of the blade 26 is determined by the fitting accuracy between the mounting hole 38 of the blade 26 and the protrusion 48b of the hub flange 48, the inner peripheral surface of the mounting hole 38 and the outer periphery of the protrusion 48b. By increasing the processing accuracy of the surface, it is possible to ensure the same degree of concentricity and to realize good mounting accuracy.

  As a result, in addition to the accuracy of the blade alone, high-accuracy cutting can be realized by ensuring the accuracy of mounting on the spindle shaft 46 with high accuracy.

  That is, in order to process in the ductility mode, not only the thickness of the cutting edge portion 40 of the blade 26 is made thin, but also the cutting edge portion 40 is perpendicular to the rotation axis (spindle shaft 46) of the blade 26. However, it is necessary to attach with high accuracy so that it can act on a substantially straight line. However, the required accuracy can be sufficiently satisfied.

  In the present embodiment, the hub flange 48 and the spindle shaft 46 that support the blade 26 are made of stainless steel (for example, SUS304, SUS304 is stainless steel based on JIS: Japan Industrial Standards). (Based on industrial standards) and the like. On the other hand, the blade 26 is integrally formed of the diamond sintered body 80 as described above. That is, the blade reference surface 36a is supported by the metal reference surface. According to such a configuration, even if the cutting edge portion 40 on the outer peripheral portion of the blade is heated by the cutting process or heat is generated on the spindle shaft 46 side, the heat is first uniformly transmitted to the inside of the blade 26. That is, the blade 26 is composed of a diamond sintered body 80 having a very high thermal conductivity, whereas the hub flange 48 and the spindle shaft 46 that support the blade 26 are much more heat-resistant than the diamond sintered body 80. Made of stainless steel with low conductivity. For this reason, the heat generated in these is transmitted in the circumferential direction along the blade 26, and immediately uniformed in the circumferential direction of the blade 26, resulting in a radial temperature distribution. Only the diamond part transfers heat immediately, and the stainless steel spindle shaft 46 and hub flange 48 are difficult to transmit heat in terms of cross-sectional area, etc., and there are few contact parts. And in that uniform state, thermal equilibrium is ensured.

  In addition, since there is no member that inhibits thermal expansion and no bimetal effect at the outer peripheral portion of the blade, the outer peripheral portion of the blade 26 can maintain good roundness and flatness. As a result, the cutting edge 84 provided at the outer peripheral edge of the blade acts on the workpiece W in a straight line.

  In the present embodiment, the configuration in which the blade 26 is mounted on the spindle shaft 46 via the hub flange 48 is shown. However, the blade 26 may be mounted directly on the spindle shaft 46, and the same effect is obtained. be able to.

  Next, a dicing method using the blade 26 of this embodiment will be described. This dicing method can perform a stable and accurate cutting process while plastically deforming a brittle material such as silicon, sapphire, SiC (silicon carbide), or glass without causing brittle fracture such as cracking or chipping. Is the method.

  First, the work W is taken out from the cassette placed on the load port 12 and placed on the work table 30 by the conveying means 16. The surface of the workpiece W placed on the workpiece table 30 is imaged by the imaging means 18, and the position of the line to be diced on the workpiece W and the position of the blade 26 are X, Y, and θ (not shown). The work table 30 is adjusted and adjusted by the movement axis. When the alignment is completed and dicing is started, the spindle 28 starts to rotate, and the spindle 28 is lowered in the Z direction to a predetermined height by an amount by which the blade 26 cuts or grooves the workpiece W, and the blade 26 moves at high speed. Rotate. In this state, the workpiece W is processed and fed in the X direction shown in FIG. 1 by a moving shaft (not shown) together with the workpiece table 30 with respect to the blade position, and the blade 26 attached to the tip of the spindle lowered to a predetermined height. Dicing is performed at

  At this time, the cutting depth (cutting amount) of the blade 26 with respect to the workpiece W is set. By rotating the blade 26 that requires a large number of cutting edges on the outer periphery at a high speed, one cutting edge (micro cutting edge) 84 must be set to have a critical cutting depth (Dc value) or less. This critical depth of cut is the maximum depth of cut that can be cut in a ductile mode by plastic deformation without causing brittle fracture of the brittle material.

  Here, Table 3 shows the relationship between the work material and the critical depth of cut per blade that does not crack.

  As can be seen from Table 3, for example, when the workpiece material is silicon, the critical cutting depth is 0.15 μm, so the cutting depth of the blade 26 with respect to the workpiece W is set to 0.15 μm or less. If the cutting depth exceeds 0.15 μm, cracks in the workpiece material are inevitable.

  Moreover, it can be seen that among the work materials shown in Table 3, the critical cutting depth of silicon (0.15 μm) is the smallest, and it is easier to crack than other materials. For this reason, in most materials, if the depth of cut is 0.15 μm or less, ductile mode processing is possible in which processing can proceed in the deformation range of the material without generating cracks in principle.

  Further, the peripheral speed (blade peripheral speed) of the blade 26 with respect to the workpiece W is set sufficiently higher than the relative feed speed (machining feed speed) of the blade 26 with respect to the workpiece W. For example, when the rotational speed of the blade 26 is 20,000 rpm and the outer diameter of the blade 26 is 50.8 mm, the relative feed speed of the blade 26 is set to 10 mm / s with respect to the rotational speed 53.17 m / s of the blade 26.

  Note that the control of the cutting depth and rotation speed of the blade 26 and the relative feed speed of the blade 26 with respect to the workpiece W is performed by the controller 24 shown in FIG.

  The dicing process in the ductility mode is repeatedly performed in a state where the cutting depth per time is set to be equal to or less than the critical cutting depth until the groove depth of the cutting line reaches the final cutting depth.

  When the dicing process along one cutting line for the workpiece W is completed, the blade 26 is indexed and positioned to the next cutting line to be processed next, and along the cutting line by the same processing procedure as described above. Dicing is performed.

  Then, by repeating the dicing process, when all the dicing processes along the predetermined number of cutting lines are completed, the work W is rotated 90 degrees together with the work table 30, and the cutting line described above is performed by the same processing procedure as described above. Dicing is performed along a cutting line in a direction perpendicular to the line.

  Thus, when all the dicing processes along all the cutting lines are completed, the workpiece W is cut and divided into a large number of chips.

  Here, in order to verify the effect of the present invention, the result of grooving the workpiece using the blade 26 of the present embodiment and the conventional electroformed blade in the dicing method will be described.

[Comparative Experiment 1] (silicon wafer)
As the blade 26 of this embodiment, a double-sided taper type (both V type) was used. On the other hand, as a conventional electroformed blade, a blade thickness of 50 μm (# 600) was used. Other conditions are as follows.

・ Device: Blade dicing device AD20T (manufactured by Tokyo Seimitsu)
・ Blade rotation speed: 20000rpm
・ Work feed speed (machining feed speed): 10mm / s
-Depth of cut: 30μm
・ Work: Silicon wafer (thickness: 780μm)
The results of Comparative Experiment 1 are shown in FIGS. 8A and 8B. 8A and 8B show the state of the workpiece surface after grooving.

  As shown in FIG. 8A, when the blade 26 of the present embodiment was used, it was possible to form the cutting groove without causing cracks on the workpiece.

  On the other hand, as shown in FIG. 8B, when a conventional electroformed blade was used, minute cracks were generated on the workpiece surface. Moreover, the crack had arisen also in the bottom face of the cutting groove.

  As described above, when the blade 26 of the present embodiment is used, it is possible to perform stable and accurate cutting in the ductility mode without generating cracks, compared to the case of using the conventional electroformed blade. I confirmed that I can do it.

[Comparison Experiment 2] (Sapphire wafer)
Next, a comparative experiment was performed using the same blade as in comparative experiment 1 under the following conditions.

・ Device: Blade dicing device AD20T (manufactured by Tokyo Seimitsu)
・ Blade rotation speed: 20000rpm
・ Work feed speed (machining feed speed): 10mm / s
-Depth of cut: 50μm
・ Work: Sapphire wafer (thickness 200μm)
The results of Comparative Experiment 2 are shown in FIGS. 9A and 9B. 9A and 9B show the state of the workpiece surface after grooving, FIG. 9A shows the case where the blade 26 of the present embodiment is used, and FIG. 9B shows the case where the conventional electroformed blade is used. It is.

  As is apparent from FIGS. 9A and 9B, it was confirmed that the same result as in Comparative Experiment 1 for a silicon wafer was obtained even when the workpiece was changed to a sapphire wafer.

[Comparison Experiment 3] (SiC wafer)
Next, a comparative experiment was performed using a straight blade under the following conditions. The blade thickness was 20 μm, 50 μm, and 70 μm.

・ Device: Blade dicing device AD20T (manufactured by Tokyo Seimitsu)
・ Blade rotation speed: 20000rpm
・ Work feed speed (machining feed speed): 2mm / s
-Depth of cut: 200μm
・ Work: 4H-SiC wafer Si surface (thickness 330μm)
10A to 10C show the state of the workpiece surface after grooving by the blade 26 of this embodiment. FIG. 10A shows a case where the blade thickness is 20 μm, and FIG. 10B shows a case where the blade thickness is 50 μm. FIG. 10C shows the case where the blade thickness is 70 μm.

  Ideally, the blade thickness should be 50 μm or less, but in the case of SiC, with a 70 μ blade thickness, there were small cracks but no significant cracks.

[Comparison Experiment 4] (Cemented carbide)
Next, a comparative experiment was performed under the following conditions using a straight blade as before. The blade thickness was 20 μm.

-Equipment: Blade dicing equipment AD20T (manufactured by Tokyo Seimitsu, AD20T is equipment model number)
・ Blade rotation speed: 10000rpm
・ Work feed speed (machining feed speed): 1mm / s
-Depth of cut: 40μm
・ Work: Carbide WC (WC: Tungsten Carbide)
11A and 11B show a workpiece surface (FIG. 11A) and a cross section (FIG. 11B) after grooving by the blade 26 of the present embodiment. As shown in the figure, ideal ductile mode processing can be performed even with a hard material such as carbide WC.

[Comparative Experiment 5] (Polycarbonate)
Next, a comparative experiment was performed under the following conditions using a straight blade as before. The blade thickness was 50 μm.

・ Device: Blade dicing device AD20T (manufactured by Tokyo Seimitsu)
・ Blade rotation speed: 20000rpm
・ Work feed speed (machining feed speed): 1mm / s
・ Cut depth: 500μm (full cut)
Work: Polycarbonate FIG. 12A and 12B show a work surface and a work cross section after grooving by the blade 26 of the present embodiment, respectively. As shown in FIG. 12A, a sharp cutting line is observed when viewed from the workpiece surface. As shown in FIG. 12B, it can be seen that a mirror cut surface was obtained even when compared with a conventional electroformed blade.

[Comparison Experiment 6] (CFRP: carbon-fiber-reinforced plastic)
Next, a comparative experiment was performed under the following conditions using a straight blade as before. The blade thickness was 50 μm.

・ Device: Blade dicing device AD20T (manufactured by Tokyo Seimitsu)
・ Blade rotation speed: 20000rpm
・ Work feed speed (machining feed speed): 1mm / s
・ Cut depth: 500μm (full cut)
・ Work: CFRP
The results of Comparative Experiment 6 are shown in FIGS. 13A and 13B. 13A and 13B show the state of the workpiece cross section after grooving, FIG. 13A shows the case where the blade 26 of the present embodiment is used, and FIG. 13B shows the case where the conventional electroformed blade is used. It is.

  Compared with the conventional electroformed blade, the electroformed blade tears each fiber, so that a clean cross section of the fiber cannot be observed, but with the blade according to the present invention, each fiber is entangled and not sharply broken. It is possible to obtain a cut surface having a proper fiber end surface.

  As a result, in the case of the blade according to the present invention, continuous cutting edges are formed, and each concave portion becomes a cutting edge and diamonds are bonded to each other. Therefore, in the electroformed blade, the cutting edge absorbs the impact with a soft binder to cut one fiber, and the cutting edge does not act sharply, but the blade according to the present invention is due to the shear stress of diamond. This is because the cutting edge acts sharply without absorbing an instantaneous impact.

  Next, the reason why a practical dicing process is possible even when the cutting process in the ductile mode process is performed by setting the cutting depth of the blade 26 to the workpiece W to be equal to or less than the critical cutting depth (Dc value). To do.

  For example, consider a case where a workpiece W made of a silicon wafer is cut using a blade 26 having an outer diameter of 50 mm. It is assumed that cutting edges (fine cutting edges) along the crystal grain boundaries are provided along the circumferential direction at a pitch of about 10 μm at the outer peripheral edge of the blade. In this case, since the outer peripheral length of the blade is 157 mm (157000 μm), about 15700 cutting edges are formed on the outer peripheral portion.

First, it is assumed that a cut of 0.15 μm is made as a cut that does not cause a crack on the workpiece W by one cutting edge, and the removal amount at one time is 0.02 μm (20 nm). Normally, the critical cutting depth at which cracks such as SiC, Si, sapphire, and SiO ₂ do not occur is on the order of submicron (for example, about 0.15 μm). Then, since there are 15700 cutting edges at the outer peripheral edge of the blade, the processing can be advanced by 0.314 mm (314 μm) in principle per blade rotation. If the dicing spindle is 10,000 rpm, 166 revolutions per second. Therefore, the cutting removal exclusion distance at the outer peripheral edge of the blade per second is 52.124 mm. For example, when the blade feed rate is 20 mm / s, the speed at which the workpiece material is processed and removed in the shearing direction is faster than the speed at which the workpiece material moves while being pushed. In other words, when cutting the workpiece material, a minute cut is made to such an extent that the workpiece material does not break, and the workpiece material is machined in a horizontal direction perpendicular to the blade traveling direction, and then removed. The removed part becomes a form in which the blade advances. For this reason, there is no room for incision of 0.1 μm or more enough to cause cracking, so that it is possible to perform cutting in a ductile mode processing region based on plastic deformation without causing brittle fracture. In other words, by rotating the blade at high speed, the peripheral speed of the outer peripheral edge (tip) of the blade due to blade rotation with respect to the material to be processed is larger than the feed speed of the blade with respect to the material to be processed. Can be performed.

  Actually, it is carried out with a little allowance in consideration of some eccentricity of the blade, and with a blade diameter of 50.8 mm, it is processed at a feed rate of about 10 mm / s while rotating at 20,000 rpm. In this case, no cracking of the material occurs.

  Next, the results of various investigations for realizing processing in the ductility mode using the blade 26 of the present embodiment will be described.

[About the cross-sectional shape of the blade cutting edge]
In the present embodiment, the cross-sectional shape of the cutting edge portion 40 provided on the outer peripheral portion of the blade 26 is a double-sided taper type (both V-type) shown in FIG. 4B among the cross-sectional shapes shown in FIGS. 4A to 4C. Preferably used.

  FIG. 14 is an explanatory view schematically showing a state in which dicing is performed using a blade 26 having a double-side tapered type cutting edge portion 40. First, the tip end portion 40a provided at an arbitrary position of the cutting edge portion 40 of the blade 26 is the deepest portion (the bottommost portion) from the surface portion of the workpiece W, as shown from the (A) portion to the (C) portion in FIG. The workpiece W is ground while gradually moving to a point). Thereafter, as shown from (C) to (D) in FIG. 14, the tip 40 a of the cutting edge 40 gradually moves from the deepest part of the workpiece W toward the surface. At this time, a gap S is formed between the side surface of the grinding groove and the side surface of the blade 26.

  That is, in the region where the cutting edge portion 40 of the blade 26 is cut inward from the surface of the workpiece W, the blade W is a cutting portion 60 where the workpiece W is ground on the upstream side in the blade rotation direction, while the blade side surface on the downstream side. A gap S is formed between the (side surface of the cutting edge portion 40) and the side surface of the groove, and the workpiece W is not ground, and the waste ground by the upstream cutting portion 60 is discharged into the groove. 62.

  In general, burrs and chipping are caused by rubbing against the side surfaces of the groove when the blade is pulled out of the material. For this reason, for example, as shown in FIG. 15, when a straight type blade 90 in which side surfaces on both sides are processed in a straight shape is used, the blade tip (cutting edge) enters the work W from the inside to the outside. The blade side constantly contacts the side of the cutting groove until it comes out. For this reason, as compared with the double-side tapered blade 26, the side surface of the cutting groove and the side surface of the blade are rubbed more easily when the blade tip part comes out of the workpiece W, and as a result, causes burrs and chipping (in FIG. 15). (D) part, (E) reference). In addition, when an electroformed blade in which diamond abrasive grains are embedded is used, the abrasive grains protruding from the blade side surface tend to scratch the groove side surface and facilitate the generation of burrs and chipping on the groove side surface.

  On the other hand, according to the blade 26 having the both-side tapered type cutting edge portion 40, when the blade 26 comes off from the workpiece W as described above, the gap S is generated between the blade side surface and the groove side surface. Therefore, no burr or chipping occurs. Moreover, the heat generated at the time of grinding can be discharged together with the chips as the chips are discharged. This makes it possible to prevent the blade 26 from warping.

  That is, the workpiece W is cut until the cutting edge portion 40 of the blade 26 cuts into the workpiece W and reaches the lowest point, and then the blade 26 passes through the lowest point of the workpiece W. Since the blade 26 is pulled out from the workpiece W in a state where the gap S is formed between the blade side surface and the groove side surface in the extraction process, it is possible to effectively suppress the occurrence of chipping and the like.

  Furthermore, by performing the cutting process as described above, it contributes to minimizing the generation of heat caused by friction accompanying the contact between the blade side surface and the groove side surface. As a result, it is possible to prevent the cutting waste from being welded to the blade 26 by suppressing an increase in cutting resistance due to an increase in heat. Further, while the gap 26 is formed in the process of extracting the blade 26 from the workpiece W, the cutting waste is left in the groove, so that there is an effect of giving heat to the cutting waste and discharging the heat. Such cutting debris can be washed away by subsequent cleaning. Further, since it is possible to suppress the heat generation of the blade 26 and the work W, it is possible to prevent the heat generation without supplying a large amount of water to the blade 26 and the work W, and in a dry environment. It becomes possible to process.

[Relationship between grain size and content of diamond abrasive grains]
In the present embodiment, it is necessary to consider the abrasive grain arrangement in the circumferential direction of the blade 26 in order to perform processing in the ductile mode. The reason is as follows.

  First, in order to make a cut of 0.15 μm, it is desirable that the size of the cutting edge (fine cutting edge) for making the cut is a large abrasive particle size or cutting edge interval of about one digit. When the cutting edge interval is 3 digits or more, it is difficult to make a fine cut in consideration of variations in the cutting edge interval.

In general, the maximum depth of cut is calculated geometrically when a flat sample is processed by moving a blade having cutting edges set at substantially equal intervals. Hereinafter, based on FIG. 16, if the hatched portion is a chip portion per blade, the AC length determined by the line connecting the blade center O and one point A on the chip is the maximum cut per blade. Depth g _max .

D is the blade diameter, Z is the number of blade cutting edges, N is the blade rotation speed per minute, V _S is the blade circumferential speed (πDN), V _W is the workpiece feed speed, and S _Z is per blade The feed amount a is the depth of cut.

there,

If the cutting depth g _max is sufficiently smaller than the blade diameter D,

Therefore,

Here, instead of the number of blades Z, using the cutting edge interval λ and substituting into equation (1) as Z = πD / λ, the maximum cutting depth per blade is obtained.

Here, PaiDN clearly equal to the blade peripheral velocity _{V S.} That is, in flat plate processing with a blade, the relationship between the cutting edge interval λ and the maximum cutting depth per blade is given by the following equation.

However, g _max: Unit cutting edge per depth of cut, lambda: cutting edge spacing, V _omega: work feeding speed, V _s: blade speed, a: blade cutting depth, D: the blade diameter.

  It can be seen from this that the interval between the cutting edges is important in order to keep the depth of cut per unit cutting edge below a certain level. Also, the rotational speed of the blade is important.

According to the relationship shown in the equation of g _max , even when V _ω : 40 mm / s, V _s : 26166 mm / s, a: 1 mm, D: 50 mm, λ: 25 μm, only the cut amount is about 0.027 μm. The cut amount is 0.1 μm or less. If it is within this range, it is below the critical cutting depth, and therefore is the range of ductile mode machining.

  In order to perform ductile mode machining, the above conditions must be satisfied.

Furthermore, as a practical condition, a 2-inch blade (diameter 50 mm) is processed by rotating at 10,000 rpm, the workpiece thickness is 0.5 mm, the workpiece feed rate is 10 mm / s, and the blade outer periphery is cut. the edge spacing and formed at 1mm pitch _{(V ω: 10mm / s,} V s: 157 × 10 4 mm / s, a: 0.5mm, D: 50mm, λ: 1mm).

  Even under these conditions, when substituting into the above equation, the critical depth of cut by one blade is 0.08 μm, and the depth of cut is still 0.1 μm or less. Therefore, if the blade is not eccentric and ideally all cutting edges act on the workpiece removal processing, critically, if the cutting edge interval that can be formed on the outer periphery of the blade is 1 mm or less, it is fatal. It is possible to proceed the processing without giving excessive cuts that cause cracks.

  In SiC, the critical cutting depth that does not cause cracking is about 0.1 μm. In other sapphire, glass, silicon, etc., the critical cutting depth that does not cause the same crack is about 0.2 to 0.5 μm, so if the critical cutting depth is set to 0.1 μm or less, most brittle materials Can be processed within the plastic deformation region of the material without cracking.

  Therefore, it is desirable that the interval between the cutting edges attached around the blade is 1 mm or less.

  On the other hand, the cutting edge spacing around the blade is preferably 1 μm or more. If the average cutting edge interval is 1 μm or less, that is, when the cutting edge interval is in the submicron order, the critical cutting depth amount and the material removal depth unit are approximately the same. That is, both are on the order of submicrons, but under such conditions, it is difficult to actually reach the removal amount expected by one cutting edge, and conversely, the machining speed is rapidly reduced by the clogging mode.

  Under such circumstances, it is considered that the depth at which one cutting edge can be removed is not possible, apart from the critical cutting depth of one cutting edge.

  The above idea holds when the cross-sectional area for cutting the workpiece is constant. That is, the sample is a substantially flat sample, the blade is rotated at a high speed, the blade is set to a constant cutting depth with respect to the flat workpiece, and the content of the blade matches with the content of the blade that is cut while sliding the workpiece.

  In the above formula, it is important that the critical cutting depth given by one cutting edge depends on the cutting edge interval. The amount by which one cutting edge cuts affects the distance from the next cutting edge, and if there is a part with a large cutting edge interval in a certain part, it indicates the possibility of causing a cutting crack deeper than the desired critical cutting depth. . Therefore, the cutting edge interval is an important factor, and in order to obtain a stable cutting edge interval, a PCD material obtained by sintering single crystal diamond is preferably used so that the cutting edge interval is naturally set from the material composition. It is used.

  However, even if the diameter of the diamond abrasive grains (average particle diameter) is large, the gap is closely packed, and if the substantial abrasive grain spacing is on the order of smaller than the grain diameter, the abrasive grains further It is possible to suppress and control the cutting. In practice, diamond abrasive grains having an ideal grain size of about 1 μm to 5 μm are desirable.

  In addition, a particle size does not necessarily become a cutting edge space | interval. When the truing is correctly performed, the interval between the cutting edges may correspond to the particle diameter, but the cutting edge interval is larger than the abrasive particle diameter in the state of being normally cut out and dressed.

  In other words, if it is strictly defined at the grain boundary, the gap that exists on both sides of one abrasive grain is interpreted as equivalent to a cutting edge, but in reality, some abrasive grains fall off in a lump and are naturally constant. A periodic cutting edge is formed. This can form the cutting edge pitch by roughening the blades on average.

  17A and 17B show the results of measuring the outer peripheral edge of the blade with a roughness meter. Further, FIGS. 18A and 18B show photographs of the surface state. Since it is a sintered body, basically all the parts visible on the surface are composed of diamond as abrasive grains.

  Further, the irregularities on the surface are formed from diamond grain boundaries, and natural irregularities with substantially equal intervals are formed. Each of these recesses acts as a cutting edge for cutting into the material. As is apparent from the figure, this cutting edge pitch has 260 and 263 peaks in the 4 mm range, so it can be seen that the cutting edge pitch is about 15 μm pitch. This material is composed of DA200 manufactured by Sumitomo Electric Hardmetal Co., Ltd., and the particle diameter of the composed diamond particles is nominally 1 μm. Thus, even if the particle size is small, the cutting edge interval is larger than that, and as shown in the figure, they are formed at substantially equal intervals.

  Such equally spaced cutting edges are due to the blade itself being formed by a diamond sintered body made by sintering single crystal fine particles.

  In this way, the blade tip has a large unevenness in order to cut the workpiece, but in contrast to the blade tip, the blade side has a mirror-like end surface after cutting the workpiece. Grind. For this reason, the blade tip is roughly formed to cut it, and the blade side is finely formed.

  In the conventional electroformed blade, the distance between the diamond abrasive grains is usually much larger than the grain size. This is because sparsely distributed diamond abrasive grains are simply plated, and are completely different at the time of plating.

  In contrast, in the blade 26 of the present embodiment, the diamond sintered body is very hard and has high strength because the sintering aid is melted in the diamond by sintering and the diamonds are firmly bonded to each other. The Further, the diamond sintered body has a relatively large diamond content compared to the electroformed blade (see, for example, JP-A-61-104045), and has a relatively high strength compared to the electroformed blade.

  In addition, since most of the blade material is occupied by diamond, it is possible to make the other part (including the sintering aid) smaller than the diamond volume. Even if the particle diameter is large, the gap between the diamond abrasive grains can be made substantially in the micron order.

  Moreover, the recessed part between diamond abrasive grains plays a very important role in the present invention. Although the diamond abrasive grains are very hard, some of the cobalt added as a sintering aid penetrates into the diamond, but some remains between the diamond abrasive grains. Since this portion is slightly softer than diamond, it is easily worn away during cutting and has a slightly recessed shape. That is, there is a portion sandwiched between diamonds, and by making the dent between them a minute cutting edge, it is intended to obtain a stable cut without giving an excessive cut. In addition, a fine cutting edge may cause not only a dent sandwiched between diamonds but also a dent portion formed by missing diamond particles itself to act as a cutting edge. This cutting edge interval may be set to an interval that does not exceed the critical cutting depth per blade shown in the previous equation.

  For example, consider a case where diamond abrasive grains having a particle diameter of 25 μm are hardened by sintering. Here, for the sake of clarity, it is assumed that the diamond abrasive grains are 25 μm square cubes. In order to bond diamond abrasive grains, the part of 1 μm on both sides outside of 25 μm is used as a bonding part for bonding with another particle. Then, it becomes a 27μm square cube. In that case, the volume% occupied by the diamond abrasive grains is about 78.6%. Therefore, if there is a diamond content of about 80% or more, even if it is a diamond grain having a particle size of 25 μm, the gap between the diamond grains, that is, the particle interval is substantially no more than about 1 to 2 μm, and the depression The part becomes a cutting edge (a minute cutting edge) for giving a cut. Further, if the particle interval is about 2 μm, even if particles having the pitch are pushed into the workpiece material at the particle interval, the displacement of the workpiece material is one digit or more smaller than the interval of the diamond abrasive grains. That is, 0.15 μm or less. Further, assuming that cutting edges (micro cutting edges) are formed at a pitch of 25 μm, in the case of a blade diameter of 50 mm, 6280 cutting edges are formed per approximately 157 mm in the entire circumference. Assuming that the blade is rotated at 20000 rpm, 2093333 cutting edges can be applied per second.

  It is assumed that this one cutting edge makes a cut of 0.15 μm or less, and removes about 0.03 μm, which is 1/5 of that, per second. If it does so, if it is 2093333 minute cutting blades, it will be possible to remove about 62799 μm per second, and theoretically it is possible to cut about 6 cm per second.

  From these points, even in the case of diamond abrasive grains having a particle diameter of 25 μm, if the diamond content is 80% or more, the gap portion where the diamond abrasive grains are bonded is 1 to 2 μm. As a result, the stable cutting amount can be set to 0.15 μm without giving an excessive cutting amount.

  In addition, even if the diamond abrasive grain size is not 25 μm or less, if the diamond content is 80% or more, the critical depth of cut will not be exceeded in terms of cutting and material removal. No, it becomes possible to perform processing in the ductile mode without generating cracks.

  As described above, in the case of a diamond sintered body, since the diamond abrasive grains (diamond particles) are closely packed, the diamond content is very high, and the size of each diamond abrasive grain is cut off. Acts as a blade.

  In addition, the distance between the diamond abrasive grains is remarkably reduced as compared with the grain diameter of the diamond abrasive grains, and the cutting depth can be accurately controlled. As a result, the cutting depth does not become larger than a predetermined initial cutting depth, and a stable cutting depth is constantly guaranteed during processing. As a result, it is possible to perform ductile mode cutting without error.

  Note that with a large particle size of about 25 μm, the content of diamond abrasive grains can be further increased, and there is a content (diamond content) of about 93% if it is commercially available. If so, even more so, the proportion of sintering aid is reduced, i.e. the gaps between the diamond abrasive grains are actually very small.

  However, when using diamond with a large particle size of 25 μm or more, as described above, the cutting edge spacing is sufficient for performing ductile mode processing, but the blade thickness of the blade is 50 μm or less. In some cases, such large abrasive grains cannot be produced.

  This is because, for example, when manufacturing with a blade thickness of 40 μm, it is necessary to have at least two diamond abrasive grains in the blade cross section, but theoretically there are not two and 1.6 pieces.

[Blade thickness considering work material deformation]
In order to perform the ductile mode processing stably, as described above, it is necessary to make the cut in the depth direction about 0.15 μm or less. In order to stably perform this cutting, it is necessary to consider the thickness direction displacement (longitudinal displacement) of the workpiece material, which is considered from the cutting width.

  That is, when a cut is made in a direction parallel to the blade surface (a surface perpendicular to the rotation axis of the blade 26) and the workpiece material is removed in a wide range, the deformation of the work material accompanying the spread also extends in the vertical direction (cut depth direction). That is, in consideration of the Poisson's ratio of the workpiece material, it is necessary to make the cut width finite to some extent. This is because if the cut width is extremely increased, the deformation aftermath also extends in the longitudinal direction due to material deformation due to the influence of the Poisson's ratio. This is because a cutting amount exceeding the predetermined critical cutting depth is entered, and as a result, cracking of the workpiece W may be induced.

  Here, the blade thickness (blade width) of the blade capable of stably giving a cut when the influence of the Poisson's ratio is taken into consideration will be examined. Table 4 shows the relationship between the Young's modulus and Poisson's ratio of the brittle material.

  Here, it is assumed that one cutting edge cuts into the workpiece material. Further, the tip of the thin straight blade is not particularly sharpened arbitrarily, and the cross-sectional shape thereof becomes a substantially semicircular shape when processed normally.

  In such a case, for example, if a 0.15 μm cut is given in a rectangular parallelepiped shape, a parallel cut with a width of about 1 μm is given, and according to the Poisson's ratio, the incident is simply displaced in the vertical direction by about 0.17 μm. This is close to the actual depth of cut. Actually, since the Poisson's ratio affects not only the vertical displacement but also the horizontal direction, an approximate width of about 1 μm can be given as the cutting depth.

  However, as shown in FIG. 19, when a substantially semicircular blade tip (blade outer peripheral end) is cut 0.15 μm into the workpiece material, the width is not uniformly displaced in parallel. Considering the rise of the outer circumference, it is possible to cut without affecting the Poisson's ratio if the arc-shaped width is about 5 μm. That is, Rsinθ = 2.5 and R (1-cosθ) = 0.15.

  When this is calculated back, the blade radius of the tip portion is about 25 μm, and the apex angle giving the 5 μm width cut is about 12 degrees.

  Therefore, it is necessary to keep the width of the blade cut into the material within about 50 μm. Beyond that, it will act on the material simultaneously in each point plane, sometimes leading to the induction of minute cracks.

  If the curvature is more than that, that is, the blade thickness is about 30 μm, the cutting edge basically acts more locally than the above state, so the width of the cutting edge basically affects the cutting depth. It can be cut stably without affecting.

  Note that the width of the blade is also related to the buckling strength of the blade alone, although there is a viewpoint in performing the ductile mode processing.

  The blade width is also limited by the workpiece thickness.

  Here, the relationship between the width of the blade and the workpiece thickness is shown.

  The workpiece is generally supported by a dicing tape. Since the dicing tape is an elastic body, unlike a hard material such as a workpiece, the dicing tape is easily displaced in the vertical direction (Z direction) with a little stress. Here, when the workpiece is cut with a blade, the cross-sectional shape of the portion to be cut in the workpiece, the hatched portion shown in FIG. 20A becomes important.

  When the blade thickness (blade contact area) l is larger than the workpiece thickness h, i> h, the portion in contact with the blade (the portion to be processed and removed) is a horizontally long rectangle as shown in FIG. 20B. In the case where the cross-sectional portion to be removed is a horizontally long rectangle, when a distributed load is applied from above, a bending state occurs due to bending, and the maximum displacement of the bending is as follows. (Actually, it is a bending of the plate, but it is simply a problem of the beam and it is assumed that the distributed load is acting.)

  For a rectangular beam with a cross-section of depth b and height h:

Therefore, the above equation is as follows.

  The maximum deflection is inversely proportional to the cube of the workpiece thickness h and proportional to the fourth power of the blade contact area l at the central portion of the beam.

In particular, at (l / h) ³ , when l / h is 1 and l / h is smaller than 1, the bending is remarkably reduced. Conversely, when l / h is larger than 1, the bending is remarkably large. Become bigger. Thus, the case where the bending occurs depending on the shape of the relative thickness of the blade thickness (blade contact area) l and the workpiece thickness h is separated from the case where the bending does not occur.

  When this blade contact area is larger than the workpiece thickness (l> h), the workpiece bends within the contact area, but when the workpiece bends, the vibration of the workpiece due to the bending up and down intermittently in the plane. Occurs, and the predetermined depth of cut cannot be achieved. As a result, a fatal cut is given from the blade due to the longitudinal vibration of the workpiece, and the workpiece surface is cracked.

  Therefore, in particular, in the processing using the PCD blade of the present invention, since a crack-free processing is performed, it is necessary to stably and faithfully protect a predetermined cutting depth. For this purpose, in addition to setting the cutting depth by controlling the cutting edge interval, it is necessary to ensure a predetermined cutting with high accuracy by suppressing longitudinal vibration during machining of the workpiece itself.

  Therefore, the blade thickness must be smaller than the thickness of the target workpiece as shown in FIG. 20C.

  For example, when the workpiece thickness is 50 μm or less, the width (thickness) of the blade needs to be 50 μm or less.

  In this case, the workpiece does not bend in the contact area. On the other hand, a stress that bends or compresses in the contact area works, but the work is a dense continuous body in the lateral direction, and deformation is restricted by the Poisson's ratio. Therefore, it locally acts on the stress applied from the blade as a reaction force from the workpiece, and as a result, it is possible to perform processing with a predetermined cut without generating cracks.

[Comparison with conventional blades]
In the case of an electroforming blade as in Patent Document 1, diamond is dispersed and plated from above, so that diamonds are present sparsely and they protrude. As a result, the protruding portion may naturally give an excessive cut and induce brittle fracture. In addition, although the part where the bottom part and the side part of the groove | channel continue also has the workpiece | work material comprised closely mutually, a crack does not enter immediately, but the part from which a braid | blade pulls out is easy to enter a crack and a crack. This is the same as burr when the blade comes out, because the workpiece material is not continuous and unsupported.

  Moreover, in the case of the blade of Patent Document 2, there is no protruding crack because the film is formed by the CVD method. However, it is impossible to control the arrangement of the cutting edges at the blade end, the planar state of the blade side surface, and the swell.

  In particular, if it is limited to the blade side surface, the film thickness unevenness during film formation corresponds to the blade thickness unevenness as it is. In addition, since the film formation surface itself is an innocent surface, it may be in contact with the side of the material completely to induce frictional heat, and there may be a subtle swell, which may break the material.

  On the other hand, since the blade 26 of the present embodiment is integrally formed of a diamond sintered body sintered using a soft metal sintering aid, the blade outer peripheral end portion and the blade side surface portion are subjected to wear treatment. It becomes possible to mold with. Particularly, since the outer peripheral edge of the blade is a cutting edge, as described above, it is possible to further change the wear processing conditions in order to obtain a predetermined cutting edge. On the other hand, the role of the blade side surface is primarily to eliminate chips. However, taking into account the contact with the workpiece side surface, the contact with the workpiece side surface is not excessively contacted but stable. It is desirable that the side surface is roughened to the extent that it is finely cut.

  As described above, none of the techniques of the cited references is possible in that a desired surface state can be designed in accordance with the state of the outer peripheral end of the blade and the side surface of the blade, and the surface can be manufactured on such a surface.

  Note that blades used in scribing are not suitable for processing in the ductility mode for the following reasons.

  That is, in scribing, since the blade itself is not rotated, minute cutting edges that are evenly spaced are not required. Also, even if there is a cutting edge, if it is not a micro cutting edge along a crystal grain boundary of micron order but a large cutting edge, cracks will be given to the material by high-speed rotation dicing and it should be used. I can't.

  Further, even when a blade having a minute cutting edge along the crystal grain boundary is used for scribing, the minute cutting edge does not function as a cutting edge that gives a scribing crack.

  Further, scribing presses the blade in the vertical direction. Therefore, a stress is applied in a vertically downward direction to the shaft passing through the blade, and the blade is configured to slide with respect to the shaft. Since the shaft and the blade are not used in a fixed manner, the clearance of the blade with respect to the shaft is low, and the blade itself does not rotate at a high speed, so there is no need to provide a reference surface on one side of the blade.

  In addition, even when manufacturing a scribing blade with a thin cutting edge of 50 μm or less, especially 30 μm or less, the blade is received by a thin bearing, and there is no reference surface received by a wide surface on one side of the blade, so the accuracy for the workpiece is high Straightness cannot be secured. As a result, the blade with a thin cutting edge is buckled and cannot be used.

[Blade strength]
Next, the relationship between the strength (elastic modulus) of the blade material and the strength (elastic modulus) of the workpiece material will be described.

  In order for the blade to cut a certain amount into the work and proceed as it is, the blade material needs to have a high strength with respect to the work material. If the blade material is simply made of a material that is soft with respect to the workpiece material, that is, a material with a low Young's modulus, the workpiece material is If the member has a high elastic modulus, the surface of the work cannot be deformed minutely, and if it is forced to deform it, the blade itself will buckle. As a result, processing does not proceed. Here, the buckling load P of the long column supported at both ends is given by the following equation.

  Here, E: Young's modulus, I: sectional moment of inertia, l: length of long column (corresponding to blade diameter).

  In the case of a blade having a lower elastic modulus than the workpiece material, if the machining is to be advanced while suppressing buckling deformation of the blade, a cross-sectional second moment that does not cause buckling deformation is required, specifically the blade thickness. Must be thickened. However, particularly when a brittle material is processed and the blade thickness is greater than the workpiece thickness, the workpiece material surface is deformed and cracked. Therefore, the blade thickness must be thinner than the workpiece thickness.

  As a result, the blade material must have a higher elastic modulus than the workpiece material.

  Such a relationship corresponds to the difference between the conventional electroformed blade and the blade 26 of the present embodiment. That is, the electroformed blade is bonded with a bonding material such as nickel and is made of nickel as a material. The Young's modulus of nickel is 219 GPa, but for example SiC is 450 GPa. Although the diamond abrasive grains electrodeposited on nickel themselves are 970 GPa, they exist independently, and as a result, are governed by the Young's modulus of nickel. Then, in principle, since the work material is highly elastic, the blade thickness must be increased incidentally. As a result, it is necessary to increase the contact area by increasing the thickness of the electroformed blade, thereby inducing cracks and cracks.

  On the other hand, in the case of the blade 26 of this embodiment, the Young's modulus of the diamond sintered body is equivalent to 700 to 800 GPa because diamonds are bonded to each other. This is almost comparable to the Young's modulus of diamond.

  Here, when the elastic modulus of the blade 26 is larger than the elastic modulus of the workpiece W, when the blade 26 is cut, not the blade 26 but the surface on the workpiece W side is deformed. While the workpiece W side is deformed, it is possible to cut and remove the workpiece as it is. In addition, the blade 26 does not buckle and deform in the process. Therefore, even a very sharp blade 26 can be processed without buckling.

  Table 5 shows the Young's modulus of each material. As is apparent from Table 4, the diamond sintered body (PCD) has a significantly higher Young's modulus than most materials such as sapphire and SiC. For this reason, even a blade thinner than the workpiece material thickness can be processed.

  Next, the relationship between the hardness of the workpiece material and the blade material will be described, but the high degree relationship is the same as the above elastic modulus.

  When the hardness of the blade material is lower than the hardness of the workpiece material, for example, in the case of an electroformed blade, diamond is supported by soft copper or nickel. The surface diamond abrasive has a very high hardness, but the hardness of nickel under which the diamond abrasive is supported is extremely low compared to diamond. Therefore, when an impact is applied to the diamond abrasive grains, the nickel underneath absorbs the impact. As a result, the hardness of nickel is dominant in the case of electroformed blades. As a result, even if hard diamond abrasive grains collide with the workpiece material and attempt to cut the workpiece, the binder absorbs the impact. Therefore, it is difficult to give a predetermined cut as a result. Therefore, in order to advance the processing, the processing does not proceed unless a blade rotation speed of a certain level or more is given to the diamond. At this time, since the impact is absorbed by nickel for a moment and the reaction force is applied to the diamond abrasive grains and presses the work material with a large force, the work material is brittlely broken.

  On the other hand, in the case of the blade 26 of the present embodiment, the diamond sintered body has a hardness comparable to that of a diamond single crystal, and is much higher than a hard and brittle material such as sapphire or SiC. As a result, even if a cutting edge (micro-cutting edge) made of a recess formed on the surface of the diamond sintered body acts on the workpiece material, the impact acts on the micro-cutting blade portion as it is, and sharp Combined with the tip portion, it is possible to accurately remove and process a very small portion.

  As described above, according to the present embodiment, the diamond sintered body 80 having a diamond abrasive grain 82 content of 80% or more is integrally formed in a disk shape, and the outer periphery of the blade 26 has a diamond. A cutting blade portion 40 is provided in which cutting blades (micro cutting blades) formed of concave portions formed on the surface of the sintered body 80 are continuously arranged along the circumferential direction. For this reason, it becomes possible to control the cutting depth (cutting amount) of the blade 26 with respect to the workpiece W with higher accuracy than the conventional electroformed blade. Accordingly, the workpiece W can be moved relative to the blade 26 while giving a constant cutting depth to the workpiece W without being given excessive cutting. As a result, it becomes possible to cut a workpiece W made of a brittle material with the cutting depth of the blade 26 set to be equal to or less than the critical cutting depth of the workpiece, thereby generating cracks and cracks. In addition, the cutting process can be performed stably and accurately in the ductility mode.

  Moreover, the recessed part formed in the surface of the diamond sintered compact 80 functions as a pocket which conveys the chip produced when the workpiece | work W is processed. Thereby, while the discharge | emission property of a chip improves, it becomes possible to discharge | emit the heat which arises at the time of a process with a chip. In addition, since the diamond sintered body 80 has a high thermal conductivity, heat generated during the cutting process is not accumulated in the blade 26, and there is an effect of preventing an increase in cutting resistance and warping of the blade 26.

  Further, in the dicing process using the blade 26 of the present embodiment, the rotation direction of the blade 26 is preferably a down cut direction. That is, when the workpiece W is moved relative to the blade 26 while giving a cut to the workpiece W, as shown in FIG. 14, the rotational direction in which the cutting edge of the blade 26 cuts into the workpiece surface. An embodiment in which dicing is performed while rotating the blade 26 is preferable.

  Further, in the dicing process using the blade 26 of the present embodiment, when the workpiece W is moved relative to the blade 26 while giving a constant cutting depth to the workpiece W by the blade 26, fine particles are applied to the blade 26. An embodiment performed while giving is preferable.

  Here, the reason why the above aspect is preferable will be described in detail below.

  In the case of a disk-shaped blade composed of a diamond sintered body as in the present embodiment, a recess is formed in the grain boundary portion between the diamond particles. The recessed portion acts as a cutting edge. Alternatively, the cutting edge is formed by unevenness due to the naturally formed roughness, and particularly the cutting edge is formed in the concave portion.

  As for the action of the outer peripheral portion of the blade, it is necessary to remove the chips while the cutting edge mainly acts to cut the cutting edge into the work and further cut it.

  On the other hand, rather than cutting the workpiece on the blade side surface, it is important to adjust the side surface that has already been cut at the tip of the blade, while cutting the side surface of the blade. For this purpose, it is necessary to cut the workpiece side surface while smoothly lubricating the blade side surface without causing the workpiece side surface and the blade side surface to bite rather than the cutting edge acting positively.

  In order to smoothly lubricate the workpiece side surface and the blade side surface without stagnation on the blade side surface, it is effective to apply fine particles to the dicing blade.

  In particular, in the groove portion just removed from the blade tip, a new side surface of the workpiece side has just appeared, and a very active surface appears depending on the workpiece material. The active surface tends to interact with other materials, and may stick to a diamond sintered body that is a blade material in particular. In order to prevent this, it is necessary to consider the lubrication between the blade side surface and the workpiece material immediately after the blade tip is removed.

  Therefore, allowing fine particles to act on the side surface of the blade made of sintered diamond plays a large role as an effect of improving the lubrication effect between the blade and the workpiece.

  When fine particles are allowed to act on the side surface of a blade made of sintered diamond, as described above, the sintered diamond has a concave portion on the grain boundary portion or the uneven surface made of natural roughness. Has a lot. Fine particles are taken into the dent. When processing while the blade side surface is rubbed against the workpiece, the fine particles accumulated in the recessed portion formed of the diamond sintered body jump out and continuously roll between the blade side surface and the workpiece side surface. This continuous rolling of the fine particles is called a “bearing effect”, which prevents the blade and the workpiece surface from biting and forms a lubricating effect between the blade and the workpiece.

  Further, this lubrication effect is not limited to simply a lubrication effect that prevents biting between the blade and the workpiece. The bearing effect of the fine particles is that the rolling fine particles have a function of polishing the side surface of the workpiece.

  As the fine particles roll and the fine particles rub against the workpiece side surface, the workpiece side surface is polished. As a result, the workpiece side surface is cleanly mirror-finished without leaving a grinding streak that is simply ground with fixed abrasive grains. Can be formed.

  Such a lubrication effect is such that when grooves are formed on both sides of the blade along the rotation, the fine particles easily roll, that is, a bearing effect appears. For example, in the cross section in the blade radial direction, a fine V-shaped groove may be cut in the side surface at the cross section where the blade enters the workpiece. Then, the fine particles enter between the V grooves, and roll along the V grooves as the blade rotates. As a result, fine particles roll along the V-shaped groove between the workpiece material and the blade, and a bearing effect appears. When the rolling effect appears, the fine particles are different from the fixed abrasive grains and the individual fine particles change their direction to some extent and act randomly, so there is no unidirectional grinding streak left and the work material side surface has a polishing effect. Demonstrated. As a result, it is possible to obtain a mirror surface from which grinding streaks are removed.

  As a method of processing while using such fine particles, for example, the fine particles are solidified by firing in advance, and the fine particles are spilled from the surface of the blade formed by the solidified fine particles, and the spilled fine particles are formed on the side of the blade. You might recall a blade that rolls and mirrors.

  However, in the blade in which the fine particles to be rolled are fired on the blade surface in advance, as the processing proceeds, the blade gradually becomes thinner as the fine particles fall off. That is, a stable and constant groove width cannot be formed. In addition, it becomes difficult to continue supplying fine particles stably and continuously.

  In addition, in order to make the fine particles work continuously, it means that the fine particles are supplied while the blade side surface is continuously worn. In such a blade, the concave portion for storing the fine particles is stably configured. It is difficult to do this, and the recessed portion cannot be formed of diamond with high hardness. In addition, the blade member itself cannot supply a blade having arbitrary irregularities with high rigidity.

  Furthermore, since such a material that easily peels cannot secure the hardness of the blade itself that supports the base, it is difficult to give a constant cut to the workpiece while the fine particles roll.

  On the other hand, such a lubricating effect cannot be obtained with a conventional electroformed blade solidified with a binder such as nickel. This is because the electroformed blade has a shape in which diamond protrudes from the surface of the binder. In other words, the surface shape is such that there are some protrusions on the plane.

  Since the diamond exists in a protruding state, the critical cutting depth of the abrasive grains cannot be controlled when the binder forming the reference plane is removed. Therefore, a fatal crack is exerted on the workpiece side. Even if fine particles are allowed to flow as in the above embodiment, the side surface of the workpiece may be mirror-finished even if there is no dent in some cases, but the fine particles may act on the blade side surface to develop a polishing effect. On the other hand, in the situation where diamond with fixed abrasive grains protruding grinds, grinding side marks still remain on the side surface of the workpiece, and potential cracks due to protrusions enter. On the other hand, the effect of fine particles that mirrorize while rolling becomes meaningless when used in combination with a processing phenomenon that causes brittle fracture while causing cracks.

  In addition, when the blade surface is viewed, the protruding diamonds are scattered in the plane. That is, there is no dent portion where fine particles accumulate on the side surface of the blade.

  Even if the fine particles are accumulated between the portions where the diamond has fallen off, that is, between the binders such as nickel, the dent portions formed of a metal material such as nickel have a lower hardness than the material used for the fine particles. Even if the fine particles escape from the dent, the dent where the periphery is made of a metal material such as nickel is not only the dent does not act as a cutting edge. Only the blade side of the soft metal such as wear is worn, while there is almost no effect of polishing and removing the workpiece. As a result, the effect of polishing the workpiece cannot be expected simply by gradually removing the blade itself.

  When the binding material of the blade is worn by the fine particles, it means that the blade thickness is changed even during the processing due to the polishing removal action on the binding material by the fine particles. For example, when the groove width is strictly controlled in grooving or the like, it cannot be used at all in the process of wearing the blade as it is seen, and it does not make sense as a blade to be machined.

  On the other hand, in the case of a blade composed of a diamond sintered body as in the present embodiment, first, it is composed of a diamond sintered body as a premise. Further, the diamond content is desirably 80% or more.

  With respect to the blade composed of the diamond sintered body, the fine particles accumulate in the concave portion of the sintered body, and then roll with the fine particles coming out by rubbing against the workpiece. Since the periphery of the recess is made of diamond, fine particles act on the edge of the recess made of diamond to polish the workpiece.

  Since the ratio of the sintering aid is relatively high, the dent part is selectively removed by friction to form a dent, but the non-dent part is conversely diamond-rich and is usually more than the work material. Hardness increases. Therefore, the fine particles coming out of the recessed portion are supported by the high-hardness diamond at the edge portion of the recessed portion, and the fine particles roll and act on the edge composed of the high-hardness diamond. As a result, a polishing pressure is applied to the workpiece side to efficiently polish the workpiece.

  In this way, it is possible to achieve both the efficient retention of fine particles and the effect of rolling the fine particles on hard diamond.

(Particle supply method)
The method for supplying fine particles is not particularly limited as long as the above-described effects can be obtained. For example, the following methods (first to third examples) can be preferably employed. .

<First example>
As an example (first example) of supplying fine particles, there is a method of applying fine particles contained in a liquid with a capillary structure to the blade itself.

  As the fine particles to be used, fine particles such as WA white alumina abrasive grains, GC green carborundum abrasive grains, and diamond abrasive grains are preferably used. Fine particles having various particle diameters of about 0.01 μm to 10 μm may be used. What is necessary is just to optimize a particle size and the material of the fine particle to be used suitably according to a workpiece | work material and its objective. For example, in the case of cutting for the purpose of removing grinding marks on the cut side surface of a PC substrate or a copper substrate, a WA having a particle size of about 1 μm is suitable.

  Further, when these fine particles are used as powders as they are, fine fine particles are blown off by the wind pressure of a blade that rotates at high speed. Therefore, it is preferable to use fine particles suspended in a liquid. As the suspending solvent, water is an example of the simplest liquid, but it may be suspended in ethanol or IPA in order to efficiently attach fine particles to the blade surface. Further, lubricating oil such as wrapping oil may be used. The solvent for suspending the fine particles is preferably optimized depending on the characteristics of the workpiece. Even if wrapping oil or the like is used, it is supplied only to the blade and not directly to the workpiece.

  The liquid containing fine particles supplied to the blade acts only on the cut surface of the workpiece and does not act on the workpiece surface. Therefore, from the viewpoint of the work, heat generation is prevented by the lubrication effect and no special liquid is supplied to the work surface. Therefore, in a conventional wet environment, a workpiece that wets the chip on the surface and destroys the element can be processed as if it were dry processing.

  The place where the liquid acts is preferably placed just before the blade cuts into the workpiece. Since the blade rotates at a high speed and a part of the blade is blown away by the centrifugal force, it is desirable that the blade is just before entering the workpiece.

  In addition, if what is applied to the blade is a liquid not containing fine particles, it does not make any sense. In the case of applying a liquid not containing fine particles, the ability to polish the side surface of the cut workpiece basically does not work. Therefore, it does not make sense to apply a liquid that does not contain fine particles.

  In addition, a liquid that does not contain fine particles has a low viscosity. By including fine particles, the interfacial tension between the fine particles and the liquid acts to increase the binding force, and as a result, the viscosity can be increased as a whole. If the viscosity can be increased, even if it is applied to the blade, the liquid containing fine particles will not be blown off by the centrifugal force of the blade, and it is possible to efficiently apply the liquid containing fine particles to the side or tip of the blade. is there.

  For example, there is a method of processing while supplying slurry containing fine particles, but sometimes it wets other places other than the place to cut in the work, so when working the work strictly in a dry state It is not applicable.

  Further, when supplying a liquid slurry along the workpiece, the slurry does not adhere to the workpiece but needs to be low in viscosity so that it flows along the workpiece. However, in such a case, there is a problem that the slurry is blown away when the slurry contacts the blade rotating at high speed. In particular, in a blade composed of a diamond sintered body, the concave portion is very small, and when the fine particles are effectively taken into the pocket of such a portion, the wind pressure and centrifugal force of the blade are dominant, and the fine particles stay on the blade. It may be difficult to do.

  On the other hand, in the method for supplying fine particles in this example, fine particles are suspended in a liquid, and the suspension is applied to the blade side surface. As a method of application, using a capillary structure such as a brush, if the liquid is applied to the blade solid rotating from the solid on the principle of the liquid capillary, the liquid is supplied, leaving the fine particle component contained in the liquid, A method of causing fine particles to act on the blade is conceivable.

  Even if the fine particles are normally applied to the blade, it is very difficult to apply and adhere the solid fine particles to the side surface of the blade rotating at high speed.

  Therefore, it is an efficient and good method to use the liquid, dissolve the fine particles in the liquid to form a suspension, and cause the fine particles to act on the blade surface in this state.

  First, by dissolving the fine particles in the liquid, the viscosity is increased, the surface tension is increased, and a gel can be formed. A liquid enters between the fine particles, and the surface tension can be increased.

  In this way, by dissolving the fine particles in the liquid, unlike the case where only the liquid is applied to the blade, it is possible to reliably act on the blade surface as a liquid having a high surface tension with viscosity.

  As a method of applying a liquid containing fine particles to the blade surface, for example, the fine particle supply mechanism shown in FIGS. 24 and 25 can be preferably used. As shown in the figure, the blade 26 is surrounded by a flange cover 100 fixed to the spindle 28 (see FIG. 1) side, and a liquid supply pipe as a liquid supply means attached to the flange cover 100 portion. 102 and a supply mechanism 106 including a capillary structure member 104 that receives supply of a liquid containing fine particles from the liquid supply pipe 102 and transfers the supplied liquid containing fine particles to both side surfaces of the blade 26 by capillary action. Is arranged.

  As the capillary structure member 104, either a brush-like member, a brush-like member or a foam member is used. That is, a structural member in which small spaces are continuously present in the gap is used. As shown in FIG. 25, the capillary structure member 104 is slightly bent between the lower end portion of the liquid supply tube 102 and the peripheral side surface of the blade 26, and the blade structure from both sides so that the tip thereof follows the rotation direction of the blade 26. 26 is in contact with both circumferential side surfaces. The capillary structure member 104 is formed to have a required width in order to uniformly apply a liquid containing fine particles to the peripheral side surface of the blade 26.

  Further, as shown in FIG. 25, a guide member 108 made of a rigid material that guides the tip end portion of the capillary structure member 104 to the peripheral side surface of the blade 26 is provided at the lower end portion of the liquid supply tube 102. As a constituent material such as a brush-like member or a brush-like member as the capillary structure member 104, for example, a soft linear member such as a polyester wire or cotton fiber can be suitably used. If a soft linear member or the like is used, even if it contacts the side surface of the blade 26 rotating at high speed, the side surface of the blade 26 is not excessively damaged.

  Even in the capillary structure member 104 using such a soft linear member, the capillary structure member 104 is guided to the peripheral side surface of the blade 26 by the guide member 108 made of a rigid material by guiding the tip portion of the capillary structure member 104. A blade that rotates at high speed and can guide the tip of the capillary structure member 104 made of a soft linear member to contact the blade 26 without being affected by the gravity of the liquid existing in the gap in the member 104. It becomes possible to reliably supply a liquid containing fine particles to the peripheral side surface of 26.

  As described above, according to the method for supplying fine particles in this example, it is possible to apply a liquid containing fine particles to the side surface of the blade. In this way, the capillary structure itself to be applied with the liquid acting on the blade is brought into contact with the blade, and the interfacial tension acting between the liquid and the solid is used to bring the fine particles contained in the liquid into the side surface of the workpiece. Can do.

  In the method of spraying liquid on a blade that rotates at high speed, the liquid blows off on the blade, and as a result, fine particles cannot act on the blade efficiently. Thus, the fine particles can be efficiently supplied along the side surface of the blade.

  When a liquid containing fine particles is applied to the blade, the liquid adheres to the recessed portion of the blade surface due to the interfacial tension of the liquid. Since the blade is rotating at high speed by vertical rotation, a part of the liquid adhering to the blade is dried, and the heat generated by the polishing by the fine particles can be taken away by the heat of vaporization. Thus, polishing can be performed without excessive heat generation even after polishing.

  Other than just applying to the blade, there is no cooling such as splashing water on the workpiece. In some cases, the workpiece can be processed dry only by applying a small amount of liquid to the blade.

  As a result, it is possible to more efficiently proceed with physical polishing by rolling fine particles.

  Also, when the fine particles come out of the dent, the fine particles are rolled between the edge of the dent formed by the diamond particles below and the work piece, so that the fine particles rolling on the work are surely cut. The workpiece can be reliably polished while being given.

<Second example>
As another example (second example) of supplying the fine particles, there is a method in which gel-like fine particles are applied in advance to a portion where the blade advances on the workpiece.

  In this method, fine particles of high concentration are suspended in advance in a small amount of water in a portion where the blade advances, and the fine particles are adhered to the portion where the blade advances in a thin line shape. As a method of attaching, it may be extruded and attached with a syringe or the like.

<Third example>
As still another example (third example) of the method for supplying fine particles, a thin sheet coated with particles is stuck on a workpiece, and the thin sheet is cut together to naturally entrain the fine particles on the sheet. There is a method in which fine particles act between the workpiece and the blade.

  In this method, high-density fine particles are applied in advance on a thin sheet. Affixed on the substrate to be cut or grooved.

  When processing a predetermined part on a substrate, it will be processed with a thin sheet attached to the surface, but by processing the substrate while processing the thin sheet, the fine particles applied to the thin sheet While adhering to the blade surface, the fine particles are naturally supplied to the blade surface, and the substrate can be processed while entraining the fine particles adhering to the blade surface.

(Blade processing equipment)
As described above, the blade 26 of the present embodiment is composed of a diamond sintered body (PCD) formed by sintering diamond abrasive grains for processing the workpiece W in the ductile mode, that is, polycrystalline diamond. However, the surface of the polycrystalline diamond (peripheral edge) can be used for workpieces made of brittle materials in order to perform stable and accurate cutting in the ductile mode without causing cracks or cracks. Part) must have a continuous cutting edge along the circumferential direction. For this reason, it is desirable to perform processing on the blade 26 at all times or regularly or irregularly using a blade processing device described later.

  Hereinafter, specific configuration examples (first to fourth embodiments) of the blade machining apparatus according to the present invention will be described.

<First Embodiment>
FIG. 26 is a schematic diagram illustrating a configuration example of the blade machining apparatus according to the first embodiment. As illustrated in FIG. 26, the blade processing apparatus 200 </ b> A according to the first embodiment includes a blade processing unit 202 that performs processing on the blade 26. This blade processing unit 202 is an example of a cutting edge generating means, and by selectively removing the crystal grain boundary portion of the surface (outer peripheral end) of the polycrystalline diamond 26a constituting the blade 26 by electric discharge machining, A cutting edge is generated on the surface of the crystal diamond 26a.

  As a specific configuration, the blade machining unit 202 generates a discharge by applying a voltage between the machining electrode 204 disposed facing the polycrystalline diamond 26a and the polycrystalline diamond 26a and the machining electrode 204. Control for controlling each part of the power supply unit 206 (voltage application unit), the nozzle 208 (processing solution supply unit) for injecting and supplying the processing liquid between the polycrystalline diamond 26a and the processing electrode 204, and the blade processing unit 202. Part (not shown).

  As the processing liquid, a liquid having a high resistivity and close to non-conductivity is preferably used. For example, ultrapure water is suitable. When electric discharge machining is performed, the polycrystalline diamond 26a, which is a workpiece, is also in a state close to a nonconductor, and a large electric field concentration is generated in a part of the crystal grain boundary portion (sintering aid) having conductivity. . As a result, the electric field concentration effect is combined, and the melting of the grain boundary portion of the polycrystalline diamond 26a occurs selectively by electric discharge machining, which contributes to the formation of the cutting edge. In particular, when ultrapure water is used as the processing liquid, the processing speed is higher and the electrode consumption rate is lower than when oil is used, and the polycrystalline diamond 26a can be subjected to electrical discharge machining with relatively high efficiency.

  Here, when discharge oil is used as the working fluid, part of it is changed to thermally decomposable carbon, which makes it easier to detach the polycrystalline diamond, and not only the crystal grain boundaries but also the diamond abrasive grains themselves are greatly skipped. . The object of the present invention is to efficiently perform ductile mode processing by forming substantially equidistant cutting edges, but sometimes the diamond abrasive grains themselves are largely detached, thereby obstructing the formation of equidistant cutting edges. On the other hand, the polycrystalline diamond may become flat and the cutting edge may not be formed.

  Furthermore, when the discharge oil is used, it becomes a contamination particularly for a work material for a semiconductor work or an electronic component, and changes the characteristics of the material. In particular, organic components such as discharge oil cannot be easily removed even if they adhere to the surface in the processing of semiconductor materials and electronic component materials. Will change.

  Therefore, in consideration of the cleanliness of the workpiece surface, the discharge oil cannot be used as it is, and in the present invention, in electric discharge machining for the purpose of cutting edge regeneration for polycrystalline diamond, it becomes a major hindrance factor. .

  The processing electrode 204 is disposed to face the polycrystalline diamond 26a with a gap. The processing electrode 204 is configured by a strip electrode, a disk electrode, a wire electrode, or the like. For example, in the case where the processing electrode 204 is configured by a wire electrode, the wire electrode is fed out from a wire supply unit (not shown), and the wire electrode is wound up by the wire recovery unit, and moves between them. Electric discharge machining is performed with the wire electrode facing the polycrystalline diamond 26a, which is the workpiece. The shape of the machining electrode 204 is not particularly limited as long as it can generate a discharge with the polycrystalline diamond 26a.

  The processing electrode 204 is preferably a metal electrode or an electrode material (e.g., carbon) that elutes into the processing liquid and becomes metal ions. As described above, a non-conductive liquid is used as the processing liquid. However, in order to facilitate local electric discharge machining due to electric field concentration, the electrode material of the processing electrode 204 is made of a non-conductor on the other side (in this example, Polycrystalline diamond). In order to attach the electrode material, it is desirable to ionize, and by ionization, the electrode material dissolves in a minute amount in the processing liquid and adheres to the counterpart polycrystalline diamond. Thereafter, a selective erosion effect is produced by the discharge due to the electric field concentration effect.

  An interval between the polycrystalline diamond 26a and the processing electrode 204, that is, a discharge gap (distance between the electrodes) needs to be several μm to several tens of μm in order to generate a stable discharge. By maintaining such a discharge gap, dielectric breakdown occurs when a voltage is applied between the polycrystalline diamond 26a and the processing electrode 204.

  In order to maintain this discharge gap in an appropriate state, it is preferable to include a discharge gap adjusting means for changing a relative distance between the polycrystalline diamond 26a and the processing electrode 204. The discharge gap adjusting means has electrode moving means for moving the machining electrode 204, and the discharge gap is adjusted by changing the position of the machining electrode 204 with respect to the polycrystalline diamond 26a by this electrode moving means. The electrode moving means is constituted by a driving device such as a piezoelectric element, a linear motor, or a motor, for example. In place of the processing electrode 204, the polycrystalline diamond 26a may be moved, or both the processing electrode 204 and the polycrystalline diamond 26a may be moved.

  According to the aspect provided with the discharge gap adjusting means, the discharge gap can be maintained in an appropriate state, and stable electric discharge machining can be performed. In addition, wear (consumption) of the machining electrode 204 may progress with electric discharge machining, but the discharge gap can be adjusted according to the degree of wear of the machining electrode 204, so that machining accuracy of electric discharge machining is improved. It becomes possible. In addition, the number of replacements of the machining electrode 204 can be reduced, work and costs associated with the replacement of the machining electrode 204 can be reduced, and work efficiency can be increased.

  Moreover, in the aspect provided with the discharge gap adjustment means, the aspect provided with the discharge gap detection means for detecting the discharge gap is more preferable. In this case, the discharge gap adjusting means changes the relative distance between the polycrystalline diamond 26a and the machining electrode 204 based on the discharge gap detected by the discharge gap detecting means, so that the discharge gap is determined in advance. Adjust to the set value. As a result, the discharge gap can be automatically adjusted in accordance with the degree of wear (consumption) of the machining electrode 204 that occurs with electric discharge machining, so that machining accuracy can be increased and electric discharge machining can be stabilized. It becomes possible.

  As an example of the discharge gap detecting means, there is an aspect constituted by an electrode voltage detecting means for detecting an electrode voltage generated between the electrodes of the polycrystalline diamond 26a and the machining electrode 204. In this case, the discharge gap adjusting means changes the relative distance between the polycrystalline diamond 26a and the processing electrode 204 based on the interelectrode voltage detected by the discharge gap detecting means (interelectrode voltage detecting means). In addition, the discharge gap detection means is not limited to the above-described mode, and for example, various optical, magnetic, and electrical methods can be employed.

  Further, in the blade machining apparatus 200A of the present embodiment, since electric discharge machining is performed while rotating the blade 26, wear of the machining electrode 204 progresses, and part of the machining electrode 204 may be locally worn. In this case, as described above, a mode in which the discharge gap is automatically adjusted using the discharge gap adjusting unit and the discharge gap detecting unit is preferable. However, instead of or in addition to this mode, the following mode is used. Can also be preferably employed.

  That is, when the machining electrode 204 is unevenly worn, electric discharge machining is interrupted, and the blade 26 is brought into contact with the surface of the machining electrode 204 while moving the blade 26 relative to the machining electrode 204 while rotating. Thus, the surface of the processing electrode 204 is processed. Thereby, the surface of the machining electrode 204 can be corrected, and uneven wear of the machining electrode 204 can be eliminated. According to this aspect, since the machining electrode 204 worn with electric discharge machining can be regenerated, the number of exchanges of the machining electrode 204 can be reduced, and it occurs with the exchange of the machining electrode 204. Work and cost can be reduced, and work efficiency can be improved.

  The power supply unit 206 has one electrode terminal connected to the polycrystalline diamond 26 a and the other electrode terminal connected to the machining electrode 204, and applies a pulse voltage between the polycrystalline diamond 26 a and the machining electrode 204. As the polarity at the time of electric discharge machining, an embodiment in which the polycrystalline diamond 26a side is an anode and the machining electrode 204 side is a cathode is preferable. The conditions such as the pulse width, pulse interval, and voltage of the pulse voltage applied between the polycrystalline diamond 26a and the machining electrode 204 are such that a discharge is generated between the polycrystalline diamond 26a and the machining electrode 204. It is set as appropriate according to the material, the distance between the electrodes, the type and supply amount of the processing liquid.

  Further, the power supply unit 206 preferably applies a bipolar pulse voltage or an alternating voltage in which the polarity between the polycrystalline diamond 26a and the processing electrode 204 is alternately reversed. According to this aspect, the electrode to the polycrystalline diamond 26a is formed by performing electric discharge machining on the grain boundary portion on the surface of the polycrystalline diamond 26a while alternately reversing the polarity between the polycrystalline diamond 26a and the machining electrode 204. The material is repeatedly attached and detached, and efficient and local electric discharge machining becomes possible.

  In the blade machining apparatus 200A configured as described above, after moving the blade 26 to a predetermined position (electric discharge machining position) before or after machining the workpiece W, the blade 26 is rotated while being driven. While supplying a machining liquid between the polycrystalline diamond 26a and the machining electrode 204, a pulse voltage is applied between the polycrystalline diamond 26a and the machining electrode 204 to generate a discharge. As a result, electric field concentration occurs in the crystal grain boundary portion on the surface (outer peripheral end portion) of the polycrystalline diamond 26a to cause erosion, and the erosion portion acts as a cutting edge. As a result, a continuous cutting edge along the circumferential direction can be generated on the surface of the polycrystalline diamond 26a. Thereafter, when machining the workpiece W, the blade 26 is moved to the original position (work machining position), and the blade 26 is rotationally driven to machine the workpiece W.

  In the present embodiment, as an example, an embodiment in which the electric discharge machining is performed offline before, during, or during the machining of the workpiece W is shown. It is also possible to preferably adopt an embodiment in which the above is performed. According to this aspect, since the workpiece W is processed in a state where a new cutting edge is always generated on the surface of the polycrystalline diamond, it is possible to improve the processing efficiency and the processing accuracy.

  Next, a mechanism for forming a cutting edge by the blade processing apparatus 200A will be described.

  First, as a known example related to the present invention, there is a technique of subjecting synthetic diamond to electrical discharge machining as disclosed in, for example, Japanese Patent No. 4451155.

  However, the electric discharge machining in the above known example is completely different from the electric discharge machining aimed at by the present invention. That is, in this known example, conductive diamond formed by the CVD method is used. In the case of diamond formed by the CVD method, the position of the crystal grain boundary is determined by the degree of crystal growth, and the size and interval of the crystal grain boundary cannot be arbitrarily adjusted. The crystallinity changes greatly depending on the state. If such a grain boundary cannot be set uniquely, it does not meet the purpose of the cutting edge generation of the present invention.

  On the other hand, in the present invention, electric discharge machining is used for the purpose of forming a cutting edge on the surface of polycrystalline diamond. Moreover, the cutting edge uses the crystal grain boundary part which exists in a fixed space | interval as a cutting blade in order for each cutting blade to set fixed cutting depth. In polycrystalline diamond, diamond abrasive grains are densely spread in the space. For example, the content of diamond abrasive grains in polycrystalline diamond, which is a diamond sintered body, is usually desirably 80 vol% or more. Moreover, in order for diamond abrasive grains to couple | bond together, the content rate of the diamond abrasive grain of 70 vol% or more is required at the minimum.

  If the diamond abrasive grains are spread in this way, crystal grain boundaries formed between the diamond abrasive grains are automatically formed at equal intervals. The crystal grain boundaries formed at equal intervals correspond to the cutting edge portions, and cutting edges at equal intervals are formed for each crystal grain (diamond abrasive grain). With equally spaced cutting edges, the cutting depth that one cutting edge cuts is automatically set within a certain range, so that a predetermined cutting depth is secured stably and a fatal crack is caused to the workpiece. It will not cut like this.

  In order to use the crystal grain boundary part of polycrystalline diamond as a cutting edge, it is important to erode the crystal grain boundary part relatively deeply as compared with the crystal grain part (diamond abrasive grain). The inner part of the crystal grain is a single crystal, but the crystal grain boundary part is discontinuous even if part of it is crystallized, so that it is inferior in strength and easily eroded selectively. It is selectively eroded by causing electric field concentration in the crystal grain boundary part, and used as a continuous cutting edge aggregate having the crystal grain boundary as a cutting edge.

  In order to form a continuous cutting edge aggregate, a diamond sintered body obtained by sintering and firing diamond abrasive grains at a high temperature and high pressure, that is, polycrystalline diamond is important. As a result, the crystal grain boundary part is selectively removed by electric discharge machining, and a continuous cutting edge aggregate is formed by the erosion action along the crystal grain boundary.

  Moreover, in order to obtain a continuous cutting edge assembly for forming a constant cutting edge interval, it is necessary that the cutting edges themselves exist continuously. For this purpose, the cutting edge must be closed loop. If it breaks in the middle instead of a closed loop, the cutting edge that comes after the break will give a fatal cut. When a closed-loop cutting edge is formed and then the cutting edge is rotated, the cutting edge at an infinite interval acts, and each cutting edge constantly works within a certain cutting range. It becomes possible.

  In addition, the mechanism in which the cutting edges at a constant interval result in one cutting edge being equal to or less than the critical cutting depth is as described above, and the description thereof is omitted here.

  Here, when conductive diamond is formed by a CVD method and a dopant is used for diamond, there is a problem that electric field concentration does not easily occur only at the crystal grain boundary portion, and the formation of the cutting edge based on the crystal grain boundary is difficult to proceed. . Although it is not all suitable to include dopants in general, in order to perform electrical discharge machining by relatively clearly separating the grain boundary part from the crystal grain part, the diamond abrasive grain itself is a dielectric. The fact that some conductivity remains in the crystal grain boundary portion contributes to the selective erosion of the crystal grain boundary portion, which is desirable for the formation of a cutting edge.

From the above, the requirements required for blades to form a continuous cutting blade assembly are listed below. However, the desirable part is not an essential requirement.
A diamond sintered body (sintered diamond), that is, polycrystalline diamond, is preferably composed of a sintered body in which diamond abrasive grains are spread at a high density. At least 70 vol% or more of the portion occupied by the abrasive grains in the volume is necessary.
-As a sintering aid for polycrystalline diamond, a conductive sintering aid is desirable.
-When a conductive sintering aid is used, electric field concentration occurs at a particularly high concentration crystal grain boundary portion and is selectively consumed, contributing to the formation of cutting edges due to erosion.
・ Polycrystalline diamond should not contain much dopant. In some cases, the dopant blurs the boundary between the crystal grain boundary and the crystal grain part.
-The cutting edge formed in the outer peripheral edge part of a blade needs to be a closed loop. In the case of a disk-shaped blade, the blade constantly rotates, and a cutting edge with a constant interval acts, and the machining proceeds stably with a cutting depth within a certain range.
-It is desirable that the blade has a disk shape and has an integral structure. The uniformity of the base material is also important in forming cutting edges with a constant interval, and it is desirable that the base material is a single piece over the entire circumference.

  As described above, according to the blade processing apparatus 200A according to the first embodiment, while supplying the processing liquid between the polycrystalline diamond 26a and the processing electrode 204, the space between the polycrystalline diamond 26a and the processing electrode 204 is increased. By applying a voltage to the electrode and generating a discharge, the electric field concentrates on the grain boundary portion (conductive aid) on the surface of the polycrystalline diamond 26a and is selectively removed, so that the surface of the polycrystalline diamond 26a A continuous cutting edge can be generated. Therefore, it is possible to stably and accurately cut a workpiece made of a brittle material in a ductile mode without generating cracks or cracks.

  The polycrystalline diamond 26a constituting the blade 26 is not limited to those obtained by sintering diamond abrasive grains using a conductive sintering aid (for example, nickel or cobalt). The blade processing apparatus 200A can also be applied to a blade made of polycrystalline diamond containing no agent. Even in this case, as in the case of applying to the polycrystalline diamond 26a containing the conductive sintering aid, the electric field is concentrated at the grain boundary portion on the surface of the polycrystalline diamond to cause the erosion action. It is possible to form a cutting edge on the surface.

Second Embodiment
FIG. 27 is a schematic diagram illustrating a configuration example of a blade machining apparatus according to the second embodiment. In FIG. 27, the same reference numerals are given to the same components as those shown in the previous drawings.

  As shown in FIG. 27, the blade processing apparatus 200B according to the second embodiment includes a processing tank 210 that stores a processing liquid. An electrode holding unit 212 is provided inside the processing tank 210, and the counter electrode 204 is held on the upper surface of the electrode holding unit 212. The method of holding the counter electrode 204 is not particularly limited, but the counter electrode 204 is held on the upper surface of the electrode holding unit 212 using, for example, vacuum suction or mechanical means.

  As described above, the blade 26 is attached to the spindle shaft 46 of the spindle 28 via the hub flange 48 (see FIG. 7). An insulating layer 212 is provided on the outer peripheral surface of the spindle shaft 46 to insulate between the blade side and the spindle body side.

  A power supply brush 214 is in contact with the outer peripheral surface of the spindle shaft 46 (on the blade side with respect to the insulating layer 212), and the power supply brush 214 is connected to an anode terminal of a power supply unit (not shown). On the other hand, a power supply terminal 216 is in contact with the side surface of the machining electrode 204, and the power supply terminal 216 is connected to a cathode terminal of a power supply unit (not shown). Therefore, the polycrystalline diamond 26 a constituting the blade 26 attached to the spindle shaft 46 is set as an anode via the power supply brush 214, and the processing electrode 204 is set as a cathode via the power supply terminal 216. As in the first embodiment described above, the power supply unit preferably applies a bipolar pulse voltage or an alternating voltage in which the polarity between the polycrystalline diamond 26a and the processing electrode 204 is alternately inverted.

  The blade machining apparatus 200B also includes a servo mechanism 218 (discharge gap adjusting means) that controls the distance (discharge gap) between the polycrystalline diamond 26a constituting the blade 26 and the machining electrode 204. The servo mechanism 218 controls the discharge gap so that desired electric discharge machining is performed during blade machining by moving the machining electrode 204 relative to the blade 26. As a method of moving the machining electrode 204 relative to the blade 26, for example, only the machining electrode 204 may be moved in the machining tank 210 without changing the position of the machining tank 210, or the machining tank 210 is moved. Then, the machining electrode 204 may be moved together with the machining tank 210. Further, the blade 26 may be moved without changing the positions of the processing electrode 204 and the processing tank 210. Further, the blade 26 and the machining electrode 204 may be moved.

  The blade processing apparatus 200 </ b> B includes a nozzle 204 that supplies a processing liquid into the processing tank 210. The nozzle 204 opens at a position in the vicinity of the machining portion between the polycrystalline diamond 26a and the machining electrode 204, and locally supplies machining fluid to the machining portion during electric discharge machining. As a result, since a machining fluid flow can be created in the machining portion between the polycrystalline diamond 26a and the machining electrode 204, the electric discharge machining can be performed without being affected by the impurities generated by the electric discharge machining. .

  According to the blade machining apparatus 200B according to the second embodiment, electric discharge machining is performed in a state where the tip portion (outer circumferential edge) of the blade 26 is immersed in the machining liquid stored in the machining tank 210 while the blade 26 is rotated. Therefore, the cutting edge can be efficiently generated in the blade 26 under a stable environment.

<Third Embodiment>
FIG. 28 is a schematic diagram illustrating a configuration example of a blade machining apparatus according to the third embodiment. In FIG. 28, the same reference numerals are given to the same components as those shown in the previous drawings.

  As shown in FIG. 28, the blade machining apparatus 200C according to the third embodiment incorporates a function as a dicing machine, and a workpiece machining section 302 for machining the workpiece W and a blade machining for machining the blade 26. Part 302.

  The workpiece processing unit 302 has basically the same configuration as the processing unit 20 of the dicing apparatus 10 shown in FIG. That is, the blade 26 is attached to the tip of the spindle 28, and the workpiece W is processed by moving the blade 26 relative to the workpiece W. The blade 26 performs processing by sliding after setting a predetermined cut for the workpiece W. By appropriately selecting the rotational speed of the blade 26 and the relative feed speed of the blade 26, one cutting edge is prevented from being set to a predetermined depth or more, and ductile mode machining is performed.

  The blade machining unit 304 is disposed at a position adjacent to the workpiece machining unit 302. The blade 26 is configured to be movable between the workpiece machining unit 302 and the blade machining unit 304 by a spindle moving mechanism (not shown) while being attached to the tip of the spindle 28. In FIG. 28, as a preferred mode, a configuration is shown in which the workpiece machining section 302 and the blade machining section 304 are arranged in parallel from the upstream side along the relative movement direction (left direction in the drawing) of the blade 26 with respect to the workpiece W. However, the present invention is not limited to this. For example, the workpiece machining unit 302 and the blade machining unit 304 may be arranged in parallel in a direction parallel to the rotation axis of the blade 26.

  The blade processing unit 304 has basically the same configuration as the blade processing apparatus 200A according to the first embodiment, and includes a processing electrode 204, a power supply unit 206, and a nozzle 208.

  The processing electrode 204 is disposed so as to face the polycrystalline diamond 26 a constituting the blade 26 in a state where the blade 26 has moved to the blade processing portion 304. The processing electrode 204 is connected to the work table support member 314 via an L-shaped connection member 312 and is configured to be movable integrally with the work table 30.

  The power supply unit 206 applies a pulse voltage between the polycrystalline diamond 26 a and the machining electrode 204 to generate a discharge. In FIG. 28, as an example, the power source unit 206 is configured by a DC power source, and the polycrystalline diamond 26a side is an anode, and the processing electrode 204 side is a cathode. However, as in the first embodiment described above, for example, It is also preferable that the portion 206 is constituted by an AC power source and the polarity between the polycrystalline diamond 26a and the processing electrode 204 is alternately reversed.

  The nozzle 208 jets and supplies a machining liquid between the polycrystalline diamond 26a and the machining electrode 204, and an embodiment using ultrapure water as the machining liquid is suitable as in the first embodiment described above. is there.

  According to the blade processing apparatus 200C according to the third embodiment, after the blade 26 is moved from the workpiece processing unit 302 to the blade processing unit 304, the blade 26 is configured to rotate while driving the blade 26 in the blade processing unit 304. While supplying the machining liquid between the polycrystalline diamond 26a and the machining electrode 204, a pulse voltage is applied between the polycrystalline diamond 26a and the machining electrode 204 to generate a discharge. As a result, cutting edges are formed on the crystal grain boundary portion on the surface (outer peripheral edge) of the blade 26, and cutting edges of approximately equal intervals are generated / regenerated for each of the diamond abrasive grains that are densely spread.

<Fourth embodiment>
FIG. 29 is a schematic diagram illustrating a configuration example of a blade machining apparatus according to the fourth embodiment. In FIG. 29, the same reference numerals are given to the same components as those shown in the previous drawings.

  As shown in FIG. 29, the blade machining apparatus 200D according to the fourth embodiment incorporates a function as a dicing apparatus, as in the third embodiment described above. In particular, in this embodiment, the workpiece machining is performed. The part 302 and the blade processing part 304 are integrated.

  As a specific configuration, the blade processing apparatus 200 </ b> D includes a blade cover (flange cover) 316 that surrounds the blade 26. The blade cover 316 is fixed to the spindle 28 side, and when the blade 26 moves relative to the workpiece W, the flange cover 316 moves together with the blade 26.

  On the inner side (blade facing surface) of the blade cover 316, a processing electrode 204 is attached so as to face the blade 26 with a gap.

  In addition, a nozzle 208 for supplying a processing liquid is provided between the blade 26 and the processing electrode 204 inside the blade cover 316.

  According to the blade machining apparatus 200D according to the fourth embodiment, when the blade 26 moves relative to the workpiece W when machining the workpiece W, the machining electrode 204 attached to the inside of the blade cover 316 is constant with the blade 26. And move together with the blade 26 while maintaining the interval (discharge gap). Thereby, the electric discharge machining of the surface (outer peripheral edge portion) of the polycrystalline diamond 26a constituting the blade 26 can be performed while machining the workpiece W. That is, it is possible to perform the cutting edge formation at the blade tip and the processing of the workpiece W at the same time, and efficient processing can be performed.

  Here, although there is a part that overlaps with the above description, characteristic configurations of the blade processing apparatus 200C according to the third embodiment and the blade processing apparatus 200D according to the fourth embodiment are listed below.

(Unipolar and bipolar)
The blade processing apparatus 200C according to the third embodiment and the blade processing apparatus 200D according to the fourth embodiment both employ a mode in which elution and discharge from the blade surface are promoted by using the blade side to be processed as an anode as an example. However, not only the aspect which applies a unipolar pulse voltage but the aspect which applies a bipolar pulse voltage and an alternating voltage is also suitable. According to such an embodiment, the process of attaching metal ions to the blade surface and the process of desorbing proceed alternately, and it is possible to efficiently form the cutting edge by discharging the grain boundary portion on the surface of the polycrystalline diamond, or Cutting edge formation by partial electrolysis is performed. In particular, since electric field concentration occurs in the crystal grain boundary portion, the crystal grain boundary portion selectively adheres as compared with the other, and both of them selectively desorb.

(Insulation configuration)
Further, as a configuration for attaching the blade to the spindle, the blade is preferably insulated from the spindle. There are several methods for insulating the spindle and the blade. For example, there is a method in which the blade is formed with a coaxial grindstone, the middle of the shaft portion is made of ceramic, and the shaft is insulated.

  As another method, there is a method of insulating a flange for fixing the blade from the blade surface. This is, for example, a method in which the end face supporting the blade is anodized to eliminate conduction. As a method for supplying power to the blade, a simple brush may be brought into contact with the shaft.

(Effect of the same spindle)
The part to be machined and the part to be bladed (cutting blade generation / cutting blade regeneration) are preferably performed with the blades attached to the same spindle. Both the blade machining apparatus 200C according to the third embodiment and the blade machining apparatus 200D according to the fourth embodiment are performed in a state of being attached to the same spindle 28. If a blade is processed with a blade mounted on one spindle and then a workpiece is mounted on another spindle and the workpiece is processed, there is an attachment error. For example, when the coaxiality is deviated as an attachment error, the cutting edge at the blade tip does not act on the workpiece at the set cutting edge interval. Since it hits one piece according to the amount of axial deviation, in principle, it is not ductile mode machining in which all equally spaced cutting edges act stably. Cracks are generated on the workpiece surface due to the intermittent action of the cutting edge. In addition, there are not a few problems with runout. In particular, in the case of a thin blade, it is important for the tip of the blade to act on a straight line in order to act on the cutting edge at a constant interval. Since it comes to meander, in principle, the cutting edges with a constant interval do not always act, and as a result, ductile mode machining does not proceed. When blade machining is performed with the blade machining apparatus 200C according to the third embodiment or the blade machining apparatus 200D according to the fourth embodiment, the electric discharge machining is performed by acting on the counter electrode while rotating the blade. Even if there is a degree of coaxiality or runout, it is corrected minutely in the process of forming the cutting edge, and both coaxial accuracy and runout accuracy are improved. Therefore, there is no problem of installation error.

(Effect of slide by constant cutting)
In the blade machining apparatus 200C according to the third embodiment and the blade machining apparatus 200D according to the fourth embodiment, the work is processed while being slid so as to give a notch of a certain depth to the blade and maintain the notch. It is desirable. As shown in the mathematical formula shown above, it is possible to set so that one cutting edge is stable and does not exceed a predetermined cutting amount, and ductile mode machining is possible.

(Environmental and contamination effects)
Furthermore, when machining the tip of the blade with the same spindle as described above, it is desirable to set the workpiece machining portion and the blade machining portion at relatively close positions.

  In recent years, when a semiconductor material such as Si or an electronic component material such as SiC, GaN, or hard glass is processed, a material used as a work material tends to hate contamination. That is, if there is a contaminant, it adheres to the workpiece surface and penetrates into the material, thereby ruining the properties of the workpiece material itself.

  Machine tools use cutting oil, but semiconductors and electronic component materials do not use cutting oil in terms of contamination.

  As with cutting oil, discharge oil and the like often interfere with use in terms of contamination. In the processing of semiconductors and electronic component materials, pure water is usually used for processing. If it is pure water, it will not adversely affect the workpiece in terms of contamination.

(Effect of discharge oil on sharp cutting edge formation)
In electric discharge machining, electric discharge oil generates pyrolytic carbon. When this thermally decomposable carbon adheres to the workpiece surface, the workpiece surface is completely contaminated with carbon. In addition to adhesion of pyrolytic carbon, the heat of electric discharge machining promotes graphitization of the diamond surface. As a result, not the crystal grain boundaries but the abrasive grains themselves are eroded, and it may be impossible to form a sharp cutting edge.

(Effects of using pure water as machining fluid)
It is desirable to use pure water as the working fluid (discharge fluid). Pure water is a non-conductive liquid, and the blade to be processed is also polycrystalline diamond and is a material close to a non-conductive material. In such a configuration, an extremely large electric field concentration occurs particularly in the grain boundary portion, and only the cutting edge portion is selectively processed by the erosion action. Thereby, it is possible to form cutting edges at equal intervals along the diamond abrasive grains.

(Effect of using running water)
Moreover, as a processing liquid, in order to exhibit the effect as a continuous non-conductor liquid, it is desirable to carry out with running water. This is because it is necessary to maintain a stable insulating state continuously as a discharge environment. In order not to use the liquid once used again, it is desirable to use one-pass, for example, to flow along an inclined electrode.

(Effects of using metal electrodes as electrodes)
In addition, pure water is used as the processing liquid, and the environment is stabilized as running water. On the other hand, the counter electrode is preferably a metal electrode. Normally, when processing with pure water, if the conductor is non-conductive, the pure water portion will not conduct electricity, but this may be partially conducted by using a metal electrode. That is, a part of the electrode material dissolves in pure water to form an electrical path. As a result, a part of the electrode material adheres to the surface of the work material although it is a trace amount. Next, the attached electrode material adheres directly to the blade surface and is removed by electric discharge machining. In particular, in order for the electrode material to adhere, the electrode material needs to be a metal, and metal ions move in pure water and adhere to the opposing blade surfaces. The attached result is also clear from the analysis result of the workpiece surface.

  In each of the above-described embodiments, the grain boundary portion on the surface of the polycrystalline diamond 26a is removed by electric discharge machining. However, the present invention is not limited to this, and may be removed by electrolytic machining. The configuration of the blade machining unit that performs electrolytic machining is basically the same as the configuration of the blade machining unit 202 (see FIG. 26) that performs electrical discharge machining, and detailed description thereof is omitted here.

  Next, the electromechanical mechanism is applied to a conventional electroformed blade (blade using a metal binder by electroforming) (comparative example) and applied to polycrystalline diamond obtained by sintering diamond abrasive grains. This will be described in detail in comparison with the case (the present invention).

(When applied to conventional electroformed blades)
When electrolytic processing is performed on a conventional electroformed blade, since a metal binder is used in the conventional electroformed blade, there is no electric field concentration as shown in FIG. 30, and the surface of the electroformed blade is oxidized. At the same time, the electrolytic elution progresses sparsely as a whole. Further, unlike a blade made of polycrystalline diamond, the electroformed blade has no grain boundary and the retraction of the binder simply proceeds and the next diamond abrasive grain appears.

  This mechanism will be described in more detail. In the electroformed blade, the proportion of the metal binder portion is larger than that of the diamond abrasive grains, and the binder portion gradually melts out from the rich portion when it is eluted. Further, since diamond abrasive grains are non-conductive (dielectric), no current flows in the vicinity of the diamond abrasive grains. Therefore, the binder remains in the vicinity of the diamond abrasive grains and covers the tips of the diamond abrasive grains. On the other hand, where the distance between the diamond abrasive grains is wide, the metal component that is the binder is rich, and this portion elutes gently. As a result, the vicinity of the diamond abrasive grains rises and covers the edges of the diamond abrasive grains, while the diamond abrasive grains elute like a bow in a greatly dented shape. As a result, a sharp cutting edge is unlikely to occur.

  In addition, when such a metal material (binding material) is on the surface, electric field concentration does not occur on the surface, and conversely, the electrolytic solution may be electrolyzed. When the electrolytic solution is electrolyzed, the oxide film covers the surface of the electroformed blade, so that the electrolytic elution is sparse and the electrolytic elution is not uniformly performed. Furthermore, not only sharp edges cannot be formed during the elution process, but when the edges are formed, the base of the diamond abrasive grains peels off and the diamond abrasive grains themselves fall off immediately.

(When applied to polycrystalline diamond obtained by sintering diamond abrasive grains)
Since the surface of polycrystalline diamond obtained by sintering diamond abrasive grains is diamond-rich, electric field concentration occurs in the sintering aid portion. Polycrystalline diamond differs from metal-plated grindstones in that diamond abrasive grains are bonded together, but even in bonded diamond abrasive grains, there are parts that are rich in sintering aids and parts that are not. To do.

  When electrolytic processing of polycrystalline diamond is performed by electric field elution, as shown in FIG. 31, the electric field concentrates particularly on a portion rich in the sintering aid. For example, when Co (cobalt) or Ni (nickel) is used as a sintering aid, electric field concentration occurs in the diamond abrasive grains where the concentration of Co or Ni in the minute sintering aid is high. The portion elutes selectively. As a result, the penetration and erosion action along the crystal grain boundary becomes remarkable. The penetration and erosion action contributes to the formation of sharp cutting edges. That is, when the permeation / erosion action occurs, the crystal grain boundary is conspicuous in the form of a deep fissure, and a sharp cutting edge is formed. Elution occurs selectively from the grain boundary portion. Since the diamond abrasive grains are very close to each other, they act deeply so as to erode between the grain boundaries. This erosion action greatly contributes to the formation of a new cutting edge.

  A sharp edge is constantly formed by erosion without accelerating the falling of the diamond abrasive grains. Further, the worn diamond abrasive grains on the surface of the polycrystalline diamond fall off due to erosion to the crystal grain boundaries. Since the diamond abrasive grains are also removed after the diamond abrasive grains are dropped, the distance between the diamond abrasive grains is still substantially uniform. The formation of the cutting edges at regular intervals is indispensable for performing ductile mode machining.

  In addition, when electrolytically processing polycrystalline diamond, as in the case of electrical discharge machining, a mode of applying a voltage that alternately reverses the polarity between the polycrystalline diamond and the processed electrode (that is, a mode of applying an alternating electric field) Is preferred. Since diamond abrasive grains are dielectric or non-conductive, elution does not proceed easily even though it is called electric field elution. At that time, by applying a voltage that alternately reverses the polarity between the polycrystalline diamond and the processing electrode, when the polycrystalline diamond side becomes the anode, a sintering aid is obtained by electrolytic elution from the surface of the polycrystalline diamond. On the other hand, when the polycrystalline diamond side becomes the cathode, conductive ions such as metal ions adhere to the surface of the polycrystalline diamond. By repeating adhesion and elution in this way, it is possible to proceed with electrolytic processing even on the surface of polycrystalline diamond as a dielectric.

  However, even in the case of electrolytic machining, the purpose of the present invention is the case where there is not much difference in the amount of elution between the grain boundary part rich in the sintering aid of the diamond sintering aid and the diamond abrasive grain part that is not the grain boundary part. Does not match. Since the object of the present invention is to generate or regenerate a sharp cutting edge in a blade made of polycrystalline diamond, the grain boundary portion rich in the sintering aid is greatly eroded in the electrolytic processing. Thus, it is desirable that the portion other than the grain boundary (diamond abrasive grain portion) does not progress so much.

  Here, the electric field is particularly concentrated at the grain boundary portion where a relatively large amount of sintering aid exists even in polycrystalline diamond. For this reason, when the surface of the polycrystalline diamond becomes a cathode, the electric field concentrates on the part where the conductive ions adhere, and the conductive ions are formed near the sintering aid. Adhere to. The adhesion and elution of the conductive ions is repeated at the grain boundary portion where the sintering aid is relatively present, which further promotes the selective erosion of the grain boundary portion where the sintering aid is present.

  In addition, it is possible to use various electrolytes as processing fluids. Conventionally, by using discharge oil, pyrolytic carbon adheres to the surface and is desorbed when it changes to an anode. The diamond surface was processed. On the other hand, further investigations by the present inventors have revealed that the surface of polycrystalline diamond can be processed with deionized water, pure water, or the like without using a discharge oil containing carbon as an electrolytic solution.

  For example, when deionized water is used as the machining fluid, a small amount of ions are present in the machining fluid, so that the electric field concentration that can be generated in the vicinity of the sintering aid for the metal of polycrystalline diamond becomes even more significant with the small amount of ions. , Greatly contribute to the local erosion effect. As a result, only the grain boundary portion, not the diamond abrasive grain portion, is significantly eroded and eluted. In particular, it can be suitably eroded by combining with an aspect in which an alternating electric field is applied.

  Further, the inventors have found that the sintering aid on the surface of the polycrystalline diamond can be selectively eluted by electric field even when ultrapure water is used as the working fluid. Originally, when ultrapure water is used as a working fluid interposed between polycrystalline diamond and a processing electrode, electric field elution occurs on the surface of the polycrystalline diamond sintered body because ultrapure water is not electrically conductive. It cannot be.

  However, a metal electrode is used as the processing electrode facing the surface of the polycrystalline diamond, and the electric field elution of the polycrystalline diamond becomes possible by combining with the above-described embodiment in which the alternating electric field is applied. Although it is not clear as a mechanism at this time, by using an alternating electric field, the metal of the electrode material is once eluted as metal ions, adheres to the surface of the opposing polycrystalline diamond, and further, the adhered part is eluted. The mechanism of being processed is becoming clear.

  At this time, the dissolved metal ions are very small, and since the opposing polycrystalline diamond is also a dielectric, the electric field is concentrated only in an extremely shallow area of the polycrystalline diamond where the concentration of the sintering aid is high. As a result, the metal ions dissolved from the facing machining electrode form a selective electrical path in the machining liquid (ultra pure water) and adhere only to the vicinity of the sintering aid. . Next, the metal ions adhering only to the vicinity of the sintering aid are dissolved together with the sintering aid, and the crystal grain boundary portion of the polycrystalline diamond, that is, the portion where there is a large amount of the sintering aid is selectively selected. Elute.

  As described above, when only the grain boundary portion of the surface of the polycrystalline diamond, that is, the vicinity of the sintering aid, is selectively eluted while causing electric field concentration, ultrapure water with extremely low conductivity is used as the processing liquid. In order to make an electrical path in the processing liquid, it is desirable that the processing electrode facing the polycrystalline diamond is made of an electrode material that dissolves into the processing liquid and becomes metal ions. In this embodiment, as an example, a copper tungsten alloy (Cu-W) is used as the electrode material of the processing electrode. However, the present invention is not limited thereto, and examples thereof include copper (Cu), aluminum (Al), and nickel (Ni). In addition to the above, any electrode material that elutes into metal ions can be suitably used.

  Further, in order to elute such an electrode material and selectively adhere and elute it to the sintering aid portion on the surface of the polycrystalline diamond, it is desirable to combine with the above-described aspect of applying the alternating electric field. When an electrolytic solution that is difficult to conduct electricity is used as the machining fluid and the electric field is concentrated on the polycrystalline diamond and repeated attachment and detachment, ideal erosion occurs, resulting in the formation of an ideal cutting edge. can do.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the above example, Of course, in the range which does not deviate from the summary of this invention, various improvement and deformation | transformation may be performed. It is. Hereinafter, modified examples will be described.

(Modification 1)
In each of the above-described embodiments, the case where electrical machining (electric discharge machining or electrolytic machining) is performed on the blade 26 composed of the polycrystalline diamond 26a has been described. However, the present invention is not limited thereto, and a tool having a similar configuration (for example, It is also possible to perform electrical machining (electric discharge machining or electrolytic machining) on a grinding machine having a configuration similar to that of the blade machining apparatus, and obtain the same effects as the above-described embodiments. be able to.

(Modification 2)
In each of the above-described embodiments, the example in which the blade 26 is mounted on the main shaft (spindle 28) extending in the horizontal direction of the blade processing apparatus has been described. However, the present invention is not limited to this, and the main shaft is vertical like a cup-type grindstone. Even if it is, it is applicable.

  DESCRIPTION OF SYMBOLS 10 ... Dicing apparatus, 20 ... Processing part, 26 ... Blade, 26a ... Polycrystalline diamond, 28 ... Spindle, 30 ... Worktable, 36 ... Annular part, 38 ... Mounting hole, 40 ... Cutting blade part, 42 ... Diamond abrasive grain 44 ... Spindle body, 46 ... Spindle shaft, 48 ... Hub flange, 80 ... Diamond sintered body, 82 ... Diamond abrasive grain, 84 ... Cutting edge (fine cutting edge), 86 ... Sintering aid, 200 ... Blade processing Device: 202 ... Blade processing unit, 204 ... Processing electrode, 206 ... Power supply unit, 208 ... Nozzle, 210 ... Processing tank, 214 ... Power supply brush, 216 ... Power supply terminal

Claims (9)

A blade processing apparatus for processing a driving blade composed of polycrystalline diamond that is a sintered bonded body of diamond abrasive grains,
A blade machining apparatus comprising cutting edge generating means for selectively removing a grain boundary portion on the surface of the polycrystalline diamond by electric discharge machining to generate a cutting edge. The drive blade is integrally formed in a disc shape,
The blade processing apparatus according to claim 1, wherein the cutting edge generating unit forms a continuous cutting edge on an outer peripheral portion of the driving blade while rotating the driving blade. The cutting edge generating means is
A processing electrode disposed opposite the surface of the polycrystalline diamond;
Voltage applying means for generating a discharge by applying a voltage between the polycrystalline diamond and the machining electrode;
A machining liquid supply means for supplying a machining liquid between the polycrystalline diamond and the machining electrode;
The a blade working apparatus according to claim 1 or 2. The blade processing apparatus according to claim 3 , wherein the processing liquid supply unit supplies ultrapure water as the processing liquid. The blade machining apparatus according to claim 3 or 4 , wherein the machining electrode is made of a metal material or a carbon material. The blade machining apparatus according to any one of claims 3 to 5 , wherein the machining liquid supply means supplies the flowing fluid in one direction between the drive blade and the machining electrode. The blade processing apparatus according to any one of claims 3 to 6 , wherein the cutting edge generating unit includes an adjusting unit that changes a relative distance between the polycrystalline diamond and the processing electrode. The blade processing apparatus according to any one of claims 3 to 7 , wherein the voltage applying unit applies a voltage at which the polarity between the polycrystalline diamond and the processing electrode is alternately reversed. A blade processing method for processing a drive blade composed of polycrystalline diamond that is a sintered bonded body of diamond abrasive grains,
A blade machining method comprising a cutting edge generating step of generating a cutting edge by selectively removing a grain boundary portion on the surface of the polycrystalline diamond by electric discharge machining.