JP6656327B2 - Work processing equipment - Google Patents

Description

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

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

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

  Patent Literature 1 discloses an electrode in which diamond abrasive grains are fixed to an end face of a metal base material (aluminum flange) by an electroforming method using an electroplating technique using a soft metal alloy such as nickel or copper as a binder. A casting blade is described.

  Patent Literature 2 describes a diamond blade formed of a base material including a plurality of diamond layers by sequentially laminating diamond layers having different hardnesses by a chemical vapor deposition (CVD) method.

JP 2005-129741 A JP 2010-234597 A

  By the way, in recent years, demands for miniaturization and high integration of semiconductor packages have increased, and thinning of semiconductor chips has progressed. Along with this, an ultra-thin work having a thickness of, for example, 100 μm or less has been required. Since such an extremely thin work is very easily broken, it is necessary to make the width of the cut groove formed by the dicing blade as small as possible when dicing the extremely thin work. For example, when cutting a work having a thickness of about 100 μm, the blade thickness of the dicing blade needs to be smaller than the thickness of the work, and needs to be at least 100 μm or less. If the cutting process is performed with a dicing blade having a blade thickness greater than the thickness of the work, the work may be broken before being cut. For this reason, for example, when a groove having a depth of about 30 μm is to be formed on a work having a thickness of about 50 μm, the width of the groove must be 30 μm or less as a matter of course. It is necessary to suppress it to 30 μm or less.

  However, the conventional dicing blade has the following technical problems, and it is not possible to stably and accurately cut an extremely thin work.

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

(Crack problem due to inability to adjust protrusion)
First, in the electroformed blade described in Patent Document 1, as shown in FIG. 21, diamond abrasive grains 92 are scattered in a bonding material (metal bond) 94, and a diamond having a sharp tip on the surface is provided. The abrasive grains 92 are in a protruding state. At this time, the protruding position and the protruding amount of the diamond abrasive grains 92 are different, and it is difficult to accurately control the protrusion of the abrasive grains in principle. For this reason, it is not possible to control the cutting depth in one processing unit with high accuracy. In particular, when cutting is performed on an extremely thin work having a thickness of 100 μm or less, a crack occurs at a certain cut or more, and the tip of the diamond abrasive grain gives a fatal cut to the work. Sometimes. As a result, there is a problem that the cracks are connected to each other to cause more or less chipping.

  The cause of such a problem is the surface morphology of the electroformed blade. That is, as shown in FIG. 21, in the electroformed blade, the diamond abrasive grains 92 are bonded by the bonding material 94, but the surface form is such that the diamond abrasive grains 92 are scattered in the bonding material 94. Existing. Therefore, in the electroformed blade, the reference plane 98, which is the overall average height position, exists near the surface of the bonding material 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 bonding material 94 that binds the diamond abrasive grains 92 is reduced, and the projection amount of the diamond abrasive grains 92 further increases. 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. That is, in the case where the incision changes greatly, a crack occurs when the incision is equal to or more than the critical incision depth (Dc value) of the material, and the ductile mode working as intended in the present invention becomes impossible.

  In particular, in the case of an electroformed blade, the diamond abrasive grains 92 worn during the cutting fall off as they are, and the new diamond abrasive grains 92 therebelow act on the diamond abrasive grains 92 during the cutting, as in the term of spontaneous cutting. However, if such a drop of the diamond abrasive grains 92 is accepted, the dropped diamond abrasive grains 92 enter between the blade and the work, and consequently promote cracks. In processing with a blade on the assumption that diamonds fall off, it is in principle impossible to prevent cracks from occurring.

(A problem that is difficult to sharpen)
Also, in the case of electroformed blades, even if the blade tip is thinly and sharply machined by machining, even if the diamond abrasive grains are sparsely present, even if it is processed to be uniformly thin or tapered. However, there is a limit to sharpening the tip of the blade because the diamond abrasive grains fall off from the surface with the processing.

  In other words, in order to produce a thin blade, when plating for electrodeposition, produce a uniformly thin-plated one and remove it from the base material to make a blade. It is difficult to form and thin by processing.

(The problem of heat accumulation caused by poor thermal conductivity)
Further, the electroformed blade has poor heat conductivity, and heat is easily accumulated in the blade due to heat generated by frictional resistance with a groove side surface during cutting, and the blade may be warped.

  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. Also, even when copper is used as the binder, the thermal conductivity is only about 398 W / m · K. If the thermal conductivity of the blade is poor as described above, heat is easily accumulated, the blade may be warped, and the heat generated during processing may cause the diamond to be graphitized. Often. Note that diamond has a thermal conductivity of 2100 W / m · K, which is an order of magnitude higher than that of nickel or copper.

(Problems in which arbitrary equally spaced cutting edges cannot be formed)
On the other hand, the diamond blade described in Patent Document 2 has the following problems.

  First, since the above-mentioned diamond blade is formed by the CVD method, it is a blade formed of a very dense film. As a result, the surface of the diamond blade becomes almost planar and arbitrarily gives a cut. Dents and pockets for removing chips cannot be formed. Further, even if minute irregularities are formed as a result, the size of the grain boundary cannot be arbitrarily set before film formation. Therefore, it is not possible to arbitrarily design the pitch of the unevenness.

(Problem 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 undulation in the film formation distribution, the undulation cannot be removed. That is, even if an attempt is made to remove the undulation by machining, cracks may be formed, and it is difficult to form a thin blade. Therefore, it is in principle difficult to improve the run-out accuracy by mounting the reference surfaces together on a spindle flange having no run-out with high accuracy.

(Securing flatness by joining dissimilar materials)
Further, in order to reduce the width of the groove cut by the blade, it is preferable that the outer peripheral portion (tip portion) of the blade is as narrow as possible. It is necessary to have a thickness that does not cause the generation. However, in the case where a blade having such different thicknesses is used for manufacturing the blade as an integral body, it cannot be manufactured as an integral body by a film forming method, which is substantially impossible. If different materials are joined for that purpose, they are deformed due to the relationship of thermal stress, and roundness and flatness are disturbed. Therefore, it is possible to realize a ductile mode processing as described later in the present invention. It can be difficult. Here, when grinding or cutting is performed, the case where the workpiece is processed in a state where helical or streamline chips are generated is referred to as ductile mode processing. That is, the process in which the removal process proceeds in the plastic deformation region before the work material is brittlely fractured without causing the work to crack is referred to as ductile mode processing.

  In the configuration where a diamond chip of high hardness is embedded on the outer periphery of the blade, the thermal expansion and thermal conductivity are different between the diamond portion and the base material. It becomes difficult to expose the tip heights of minutely different diamond tips on the same plane. Further, if the chips are arranged circumferentially, the temperature distribution does not become a clear temperature distribution that is axisymmetric, so that the flatness also deteriorates due to thermal stress.

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

  Furthermore, although the hardness of the diamond tip portion is extremely high, the impact of the diamond tip may be absorbed by the base material portion due to the elastic effect of the metal portion of the base material. When working in ductile mode, it is necessary to continuously make very small cuts, but if such a shock is absorbed by the base material, it is impossible to perform work in ductile mode under very small cuts. Can not.

  From the above, when illuminating the point of heat conduction, the point of shape flatness and continuity of the plane, the point of applying effective shear force locally without absorbing the shock due to processing, the blade in which the diamond chip is embedded is Is a problem.

(In the film formation method, stress distribution varies depending on the film deposition direction and blade warpage occurs)
Further, in the above-mentioned diamond blade, since a compressive stress is formed in a film composed of a diamond layer formed by the CVD method, the way of the stress is different as the film is deposited. For this reason, when the film is finally peeled off to form a blade, there is a difference in how compressive stress is applied on both the left and right sides, and as a result, the blade is greatly warped. Even if such a warpage of the blade is corrected, there is no means for correcting it, and there is a concern that the yield may be deteriorated due to the stress of the film.

  In the case of a blade, it is necessary to provide a cutting edge on the outer peripheral portion. The cutting edge requires some arbitrary continuous irregularities. Even if a uniform sharp blade with no irregularities on the outer periphery like a sharp knife is formed, a small cut is made in the material, such as a brittle material or, in some cases, a ductile material, while removing chips. In order to solve the problem of the present invention that the processing is advanced, it is impossible to perform the substantial cutting processing without minute irregularities on the outer peripheral portion.

(Scribing problem)
As another problem, it is not a problem of the blade itself, but, for example, an ideal blade that is manufactured with high precision, has a sharp tip, and does not change its planar state even when heated during cutting. Even if it can be manufactured, how to use the blade is also important. In particular, in the case of scribing or the like in which the blade itself is pressed in the vertical direction with respect to the workpiece to give a crack and cut, the processing obviously uses brittle fracture. Can not do.

  In scribing, the relative speed is set to 0 so that the work 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 part for sliding the blade along the work and the blade part rotating in contact with the work must not be completely fixed. There is no play on the blade and there is no direct connection 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 scribing, the motor and the blade have a directly connected structure, there is no relationship between the shaft and the bearing, and the motor and the blade are fitted in a coaxial configuration with high precision.

  For that purpose, it is important to align the blade end surface with the flange end surface directly connected to the motor. That is, the dicing blade needs a reference plane to be aligned with the end face of the flange.

(Cutting while maintaining a constant cutting depth for the workpiece)
In addition, the removal volume changes greatly with cutting, the volume itself removed by one cutting edge changes, as a result, it is not possible to control a predetermined critical depth of cut in removing one cutting edge, As a result, the cutting resistance significantly changes during the cutting process, and the unbalance may cause cracks in the work material. Also in such a case, it causes brittle fracture, and it is impossible to realize ductile mode processing. That is, in order for one cutting edge to microscopically maintain a constant cutting depth with respect to the work, it is necessary to provide a constant cut to the work and to secure a steady state during processing.

  If the work is not a flat sample, the work may not be fixed properly. For example, when a cylindrical work is cut as it is, the work moves, and not only the cut is not constant but also the work may vibrate due to the cutting.

On the other hand, recently, there is also 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 material with a low dielectric constant are mixed). In a brittle material such as a low-k material, the work must be processed within a deformation range of the material so as not to cause brittle fracture. On the other hand, Cu does not crack because it is a ductile material. However, such materials tend to stretch very much while not cracking. Such highly ductile materials cling to the blade and generate large burrs where the blade comes off. Further, in the case of a circular blade, a burr-like burr is often formed on the upper part.

  Further, in the case of a material having high ductility, if the material is dragged by the blade even after cutting, there is a problem that the material sticks to the blade. When clinging to the blade, clogging of the blade is accelerated, the cutting edge portion of the blade is covered with the work material, and there is a problem that the grinding ability is significantly reduced.

  The present invention has been made in view of such circumstances, and it is possible to stably and accurately perform cutting in a ductile mode without generating cracks or cracks even for a work made of a brittle material. It is an object of the present invention 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 one embodiment of the present invention performs processing on a drive blade composed of polycrystalline diamond obtained by sintering diamond abrasive grains to process a work in ductile mode. A cutting edge generating means for generating a cutting edge by removing a surface of the polycrystalline diamond by electric machining.

  According to this aspect, since the cutting edge generating means for generating the cutting edge by removing the surface of the polycrystalline diamond by electric machining is provided, it is possible to generate the cutting edge on the surface of the polycrystalline diamond. Accordingly, it is possible to stably and accurately cut a work made of a brittle material in a ductile mode without generating cracks and cracks.

  In addition, even on the surface of polycrystalline diamond, especially the diamond abrasive grains are insulators because they are single crystals, but a part of the crystal grain boundary connecting the diamond abrasive grains has a slight amount of sintering aid. Is relatively conductive and has a geometrically discontinuous shape as compared with the diamond abrasive grains, so that it is a place where electric field concentration is likely to occur. Therefore, unlike electric discharge machining of ordinary metal plating or the like, the electric field is locally concentrated only at the crystal grain boundary portion, and locally high-density electric energy acts on the crystal grain boundary portion. 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 generation unit may perform electric processing offline before or after processing the work, or during processing, or may perform electric processing in-process while processing the work with the drive blade. May be performed. According to the in-process mode, the work is performed on the workpiece in a state where a new cutting edge is always generated on the surface of the polycrystalline diamond, so that the processing efficiency and the processing accuracy can be improved.

  However, even when performing electric machining offline, the same rotation axis (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 the respective processing be performed in a state where the drive blade is attached to the motor.

  When each process is performed with the drive blade attached to a different rotating shaft, even if a new cutting edge is formed on the drive blade, it is necessary to apply the drive blade to the machining of the workpiece at the stage of applying the drive blade to the work. Mounting errors occur. Since this mounting error causes eccentricity at the time of rotation, a certain minute cut is not given to the work, and sometimes a fatal crack is given to the work. Therefore, the rotation axis on which the drive blade is attached when processing the workpiece and the rotation axis when causing the drive blade to generate a new cutting edge are the same, that is, each processing is performed on the same rotation. It is desirable.

  Further, in the blade processing apparatus according to an aspect of the present invention, the driving blade is integrally formed in a disk shape, and the cutting edge generating unit is connected to an outer peripheral portion of the driving blade while rotating the driving blade. An embodiment in which a cutting edge is formed is preferred.

  In the blade processing apparatus according to one aspect of the present invention, it is preferable that the cutting edge generating unit removes a crystal grain boundary portion on a surface of the polycrystalline diamond by electric discharge machining.

  According to this aspect, it becomes possible to melt and selectively remove the crystal grain boundary portion on the surface of the polycrystalline diamond by electric discharge machining. Therefore, it is possible to generate a cutting edge on the surface of the polycrystalline diamond, and to stably and accurately cut the workpiece made of a brittle material in the ductile mode without generating cracks and cracks. It becomes possible.

  Further, in the case of polycrystalline diamond which is sintered by laying diamond abrasive grains, the cutting edges are automatically made substantially equally spaced by selectively removing them from the crystal grain boundary portions. Further, even if one diamond abrasive drops, the diamond abrasive next to it immediately functions as a cutting edge, so that the cutting edges at substantially equal intervals are continuously maintained.

  On the other hand, when sparse abrasive grains are hardened with a binder like a conventional grindstone, when one abrasive grain falls off, the surrounding area after the abrasive grains fall off immediately has no abrasive grains. , Only the binder. Therefore, the next abrasive grains do not appear unless the binder is retracted. At this point, when the cutting edge is formed by selectively eroding the crystal grain boundaries, there is basically no binder, and as soon as it falls off, the side changes to a cutting edge and the cutting edge at approximately constant intervals The blade is maintained continuously. However, with a conventional grinding wheel that retracts and removes the buried abrasive grains while removing the binder, such a continuous cutting edge interval cannot be maintained in principle. Thus, polycrystalline diamond obtained by sintering diamond abrasive grains has a completely different principle 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 a surface of the polycrystalline diamond, and a processing electrode disposed between the polycrystalline diamond and the processing electrode. It is preferable that an aspect includes a voltage application unit that generates a discharge by applying a voltage, and a processing liquid supply unit that supplies a processing liquid between the polycrystalline diamond and the processing electrode.

  This aspect shows one aspect of the cutting edge generating means. The working electrode is not particularly limited as long as it can generate a discharge between the processing electrode and the 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 tip of the blade is desirable. In this case, in the case of a disk-shaped drive blade, the electrode is made linear, or in the form of a disk facing the drive blade, in such a way as to face the tip of the arc-shaped blade. It is good to make it the structure which makes it.

  In the blade processing apparatus according to one aspect of the present invention, it is preferable that the processing liquid supply unit supplies ultrapure water as the processing liquid.

  According to this aspect, the polycrystalline diamond, which is the workpiece, is also in a state close to a non-conductor, and a large electric field concentration occurs in a part of a conductive grain boundary. As a result, in combination with the electric field concentration effect, the electric discharge machining selectively melts the grain boundaries of the polycrystalline diamond, thereby contributing to the formation of cutting edges.

  In the blade processing apparatus according to one aspect of the present invention, it is preferable that the processing electrode is formed of a metal material or a carbon material.

  Further, in the blade processing apparatus according to one aspect of the present invention, it is preferable that the processing liquid supply unit supplies the processing liquid with flowing water in one direction between the driving blade and the processing electrode.

  Further, in the blade processing apparatus according to one aspect of the present invention, it is preferable that the cutting edge generating unit includes an adjusting unit that changes a relative distance between the polycrystalline diamond and the processing electrode.

  According to this aspect, the gap (discharge gap) between the polycrystalline diamond and the machining electrode can be appropriately maintained, so that stable electric discharge machining can be performed.

  In particular, when a cutting edge is formed by eroding a crystal grain boundary portion of polycrystalline diamond, since polycrystalline diamond is also a non-conductor, it is hardly possible to work when the discharge gap is too large. Therefore, it is preferable that the discharge gap is extremely small. By controlling the discharge gap by the adjusting means, stable and efficient discharge machining can be performed.

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

  According to this aspect, the surface of the polycrystalline diamond is subjected to electric discharge machining while the polarity of the processing voltage is alternately switched between positive and negative in the gap formed by the polycrystalline diamond and the processing electrode, so that the electrode material for the surface of the polycrystalline diamond is formed. Adhesion and desorption are repeated.

  In particular, when ultrapure water is used as the working fluid, the ultrapure water is a non-conductive medium, but metal ions of the electrode material are contained in the medium (ultrapure water) due to elution of a part of the electrode material. Partial penetration, which adheres to non-conductive polycrystalline diamond. Even on the crystal grain boundary, especially on the polycrystalline diamond, the electric field concentration becomes large, and the electrode material tends to adhere. Thereafter, when the polarity changes, the electrode material adhered to the crystal grain boundary portion is desorbed, and a selective erosion effect is generated due to an electric field concentration effect on the crystal grain boundary portion of the polycrystalline diamond. Thereby, efficient and local electric discharge machining can be performed. The voltage for alternately inverting the polarity between the polycrystalline diamond and the processing electrode includes a bipolar pulse voltage and an AC voltage.

  Further, in order to achieve the above object, a blade processing method according to another aspect of the present invention is directed to a driving blade formed of polycrystalline diamond obtained by sintering diamond abrasive grains for processing a work in a ductile mode. A cutting edge generating step of generating a cutting edge by removing a surface of the polycrystalline diamond by electric processing.

  According to this aspect, since the cutting edge generation step of removing the crystal grain boundary portion on the surface of the polycrystalline diamond by electric machining is provided, the cutting edge can be generated on the surface of the polycrystalline diamond. Accordingly, it is possible to stably and accurately cut a work made of a brittle material in a ductile mode without generating cracks and cracks.

  Further, the present invention includes the following technical ideas.

  A dicing apparatus according to one aspect of the present invention is a dicing apparatus for cutting a work, wherein the diamond sintered body formed by sintering diamond abrasive grains is formed in a disk shape, 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 “%”) or more, a rotating mechanism for rotating the dicing blade, and a constant cutting depth in the work by the dicing blade. A moving mechanism for moving the work relative to the dicing blade while giving the work.

  In one embodiment of the present invention, the dicing blade preferably cuts the work while rotating in a downcut direction.

  The downcut direction refers to a rotation direction in which the cutting edge of the dicing blade cuts into the surface of the work when the work is relatively moved with respect to the dicing blade.

  In one embodiment of the present invention, a cutting edge (a minute cutting edge) formed of a concave portion formed on the surface of the diamond sintered body is provided continuously along a circumferential direction on an outer peripheral portion of the dicing blade. Is preferred.

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

  In the case of the conventional electrodeposited diamond, the diamond protrudes because the binder retreats as compared with the diamond, and as a result, the protrusion of the diamond abrasive grains is larger than the average level line. As a result, the cutting depth becomes excessively large in the portion of the abrasive grain where the protrusion amount is large, and a crack is applied beyond the critical cutting depth inherent to the material.

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

  In this way, the cutting edge formed in the diamond abrasive grains is formed by the diamond abrasive grains dominantly existing in the whole, and the sintering aid that has been diffused and left in between. It becomes the cutting edge of the dent. In addition, as for the content of the diamond abrasive grains at this time, as will be described later, the vacant portion acts as a cutting edge only when the content of the diamond abrasive grains is 80% or more. When the content decreases, the concave portion is not formed in the outer edge formed by diamond abrasive grains, so the uneven portion is almost the same or the convex portion becomes dominant and relatively protrudes A part is created and does not become a cutting edge that gives a stable cutting depth below a certain level that does not cause a fatal crack on the work.

  Further, the blade according to the present invention is largely characterized by being made of sintered diamond. Sintered diamonds are produced by laying diamonds of uniform grain size in advance, adding a small amount of sintering aid, and increasing the temperature and pressure. The sintering aid diffuses into the diamond abrasive grains, resulting in a strong bond between diamonds.

  In an electroplated blade or an electroformed blade, diamonds are not connected to each other. This is a method of solidifying diamond abrasive grains by solidifying the diamond studded with surrounding metal.

  In the case of sintering, the sintering aid diffuses into the diamond, so that the diamond particles are strongly connected to each other. The properties of diamond can be exploited by combining diamond particles. With respect to the rigidity, hardness, heat conduction, and the like of diamond, if the diamond content is large, it is possible to make use of physical properties almost similar to diamond. This is due to the bonding of the diamonds.

  Compared to other manufacturing methods such as electroforming blades, the diamonds are tied together by being baked at high temperature and pressure. Such a sintered diamond is, for example, Compax Diamond (trademark) manufactured by GE. In the case of Compax diamond, fine particles composed of single crystals are bonded to each other with a sintering aid.

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

  In the case of a single crystal diamond, it is not possible to strictly control the wear process in the material in what unit the diamond is worn in the course of wear.

On the other hand, similarly, like DLC (diamond-like carbon), a member produced by vapor-phase growth by CVD is also made of polycrystal, but the size of the crystal grain boundary cannot be controlled with high accuracy. Therefore, it is not possible to set the degree of uniform wear at the time of abrasion from the grain boundaries, and it is not possible to strictly control the crystal units and the grain boundary units that are worn out and fall off by working. As a result, a large defect may sometimes occur, or a large crack may occur due to an excessive stress applied to some of the defects.

  On the other hand, PCD (Polycrystalline Diamond) in which diamond particles are fired at high temperature and pressure is polycrystalline diamond like DLC, but the crystal structure is completely different. In the PCD in which the fine particles are fired, the diamond fine particles themselves are single crystals, and are complete crystals having extremely high hardness. PCD combines single crystals by mixing a sintering aid in order to combine the single crystals. At this 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 dependence even in the abrasion process, and it has a constant large strength in any direction.

  From the above, in the case of PCD, all components are polycrystals because they are not perfect single crystals, but are polycrystals in which minute single crystals of uniform size are densely assembled.

  With such a configuration, the initial state can be accurately maintained in terms of the state of the outer peripheral cutting edge and the pitch unit of the outer peripheral cutting edge in the abrasion process in machining. In the process of abrasion by dicing, the part connecting the single crystals is relatively weak in terms of hardness and strength, rather than breaking the single crystal itself, so the bond breaks off from the grain boundary part and falls off I will do it.

  In forming a cutting edge, the PCD wears along the crystal grain boundaries between the single crystals, so that the cutting edges are naturally set at regular intervals. All the irregularities thus formed become cutting edges. Also, there are uneven cutting edges due to grain boundaries of particles between natural uneven uneven cutting edges existing at equal intervals, and all of these are made of diamond, and thus exist as cutting edges.

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

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

  In addition, as a supplement, in the "formation of equally spaced cutting edges" of the present invention, the blade in which the diamond abrasive grains are arranged in the PCD material in the present invention and the diamond abrasive grains in other general cases are arranged. The following describes the differences from the conventional blade.

  In an electroformed blade, the content of abrasive grains is small. Also in Japanese Patent Application Laid-Open No. 2010-005778, the content of diamond abrasive grains in the abrasive layer is about 10%. Therefore, it is unlikely that the abrasive content exceeds 70%. Therefore, each abrasive grain exists sparsely. Although they are arranged to some extent evenly, the spacing between the abrasive grains is large in order to secure sufficient protrusion of one abrasive grain.

  Japanese Patent No. 3308246 discloses a dicing blade for cutting a rare earth magnet, and is described as being formed of a composite sintered body of diamond and / or CBN. The content of diamond or CBN is set to 1 to 70 vol%, more preferably 5 to 50%. When the diamond content exceeds 70%, there is no problem in terms of warpage and bending, but it is susceptible to impact and easily broken.

Japanese Patent No. 4714453 also discloses a tool for cutting and grooving a composite material such as ceramics, metal, and glass. It is described that in a tool produced by firing diamond, abrasive grains are contained in the fired material in an amount of 3.5 to 60 vol%. 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 a high hardness, and it is stated that a sufficient protrusion of the abrasive grains can be always maintained with the described configuration. It is described that by maintaining "projection of abrasive grains" sufficiently, spontaneous cutting can be effectively maintained to enable high-speed machining.

  As described above, in consideration of the conventional example, neither the electroformed blade nor the diamond sintered body blade is used to spread the gap between the abrasive grains. Further, there is no idea that a gap between the spread abrasive grains is used as a cutting edge. In the present invention, in order to process in the ductile mode, the critical cutting depth given by one cutting edge is important as described later by a mathematical expression, and in order to keep the cutting depth below a certain value, the interval between the cutting edges is required. Becomes important. Also, instead of forming abrasive grains that protrude in a large isolated manner, diamonds are laid, and equally spaced cutting edges are formed by using the buried dents.

  FIGS. 22A and 22B schematically show the state of the abrasive grain interval 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 to remove some abrasive grains continuously and roughen them . For that purpose, a diamond abrasive content of at least 70% or more is required at least to spread. Then some diamonds must be removed. By sintering with a content of diamond abrasive grains of 80% or more, it is possible to form a state in which diamonds are laid without gaps at least spatially as shown in FIG. 22A. Thus, a blade having cutting edges at regular intervals can be formed naturally. In addition, all the irregularities thus formed act as cutting edges.

  From the above, in order to form the cutting edges at equal intervals, it is necessary to form the material by laying the abrasive grains at high density and firing at high temperature and pressure.

  When the content of diamond abrasive grains is 70% or less as shown in FIG. 22B, it is difficult to arbitrarily form equally spaced cutting edges. This is because if the content is 70% or less, a part where diamond abrasive grains are rich and a part where diamond abrasive grains are not formed are inevitably generated, and a part where diamond abrasive grains are sparse is inevitably cut due to the presence of isolated abrasive grains therein. This is because the interval between the blades may increase. If the distance between the cutting edges is large, or if there is a sparse part and, for example, only one diamond abrasive grain protrudes, the exact amount of protrusion cannot be set, causing a fatal crack on the workpiece. This will give the depth of cut to be effected.

In the above-mentioned Patent No. 4714453, in order to solve the problem of performing high-speed processing under sufficient protrusion of abrasive grains, the content of diamond abrasive grains is preferably 70% or less. However, in the present invention, the problem is to perform crack-free dicing in the ductile mode. Therefore, in order to use the recessed portion between the abrasive grains as a cutting edge and to keep the interval between the cutting edges constant, the diamond content should be at least 70% or more, ideally 80%. It is desirable to have the above.

  Further, the blade in this case is not simply cut with a sharp blade like a cutter. That is, the tip is not manufactured by a sharp blade and cut by the principle of pinching. It is necessary to remove the work while shaving and make grooves. It is necessary to cut the next blade into the material while continuously discharging chips, and to do so continuously. Therefore, it is not only necessary that the tip be sharp, but a minute cutting edge is required.

  In the case of such a configuration in which diamonds are densely packed, a constant cutting edge interval is formed not only by the grain boundary portion but also by the natural roughness of the outer peripheral portion. Such a cutting edge interval will be described later with a specific interval, but the diamond grain size and the cutting edge interval may be completely different sizes.

  When the cutting edge interval differs 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 the diamond is embedded in the bonding material, the individual diamonds exist independently of each other, and therefore, the size of the cutting edge becomes the same as the diamond grain size. That is, one diamond forms one cutting edge. In such a configuration, the unit of the spontaneous cutting edge is each diamond, that is, corresponds to each cutting edge. The unit of the cutting edge and the unit of the spontaneous cutting edge do not change. For example, if the workpiece needs to be caught to some extent, it is necessary to make a cut, so the cutting edge also needs to be increased, but the unit of self-generated blade also increases because the abrasive grains themselves fall off. As a result, the service life becomes extremely short.

  As described above, in the conventional electroformed blade and the like, the size of the abrasive grains and the size of the cutting edge are the same, which is a constraint 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 particles is formed on the outer peripheral portion of the sintered diamond blade formed by combining diamonds. Compared with the unit of the cutting edge, the diameter of diamond as each abrasive grain constituting the sintered body is very small, about 1 μm.

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

  As a result, in the process of spontaneous cutting, in the case of the present invention, diamond is peeled off by abrasion in a region smaller than the size of the cutting edge, and the size of the cutting edge itself does not change significantly. Within one cutting edge, dicing progresses while being peeled off very minutely and partially. As a result, the size of the cutting edge itself does not change, and on the other hand, the entire cutting edge does not wear out and the sharpness does not deteriorate. While being small and partially native, the maximum cutting depth per cutting edge is kept within a certain range. As a result, ductile mode processing can be maintained and stable sharpness can be achieved at the same time.

  Another way of thinking is to use a conventional binder, such as a dresser electrodeposited with nickel or the like, to solidify the abrasive grains.If one abrasive grain falls off, the dropped part becomes a hole. Therefore, the cutting edge disappears, and the workability corresponding to that part disappears. Therefore, in order to maintain workability, in order to make the next cutting edge easily protrude, it is necessary to design so that the binder is quickly worn to protrude the next abrasive grain.

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

  The concept of such a cutting edge, the interval and the critical cutting depth at which one cutting edge cuts, as a setting condition in dicing, set a constant blade cutting with a blade that requires a cutting edge on the outer periphery, and set the cutting. It is necessary to feed at a feed rate for the work that matches Therefore, a device that operates the blade at a constant cut and a constant feed along the surface shape is premised. When the work is flat, it is necessary to set a constant cut in parallel to the surface of the work to be machined and relatively feed the blade.

  Next, by rotating the disk-shaped blades, the cutting edge at each outer peripheral end performs the removal processing of the work at the processing point, and then cuts the sky as it is, and the blade is cooled naturally. . In particular, only a small part of the part comes into contact with the work, and most of the part is cut off and cooled.

  In the case of cutting, etc., the cutting edge keeps in contact with the work constantly, and the cutting edge portion has heat due to friction, and even diamond may be abraded thermochemically. By cutting the workpiece with the blade shaped upright, it is possible to largely avoid the abrasion of the diamond due to thermal effects.

  In one 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.

  By using soft metal as a sintering aid, the blade becomes conductive. If 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 also difficult to accurately estimate the position of the tip of the blade with respect to the work in consideration of mounting errors due to mounting on the spindle.

  Therefore, a conductive blade is used as well as conduction between the conductive blade and the chuck plate for chucking the reference planar substrate, and conduction is performed when the conductive blade comes into contact with the chuck plate. The relative height between the blade and the chuck plate can be found.

  Further, in one aspect of the present invention, it is preferable that the recess is constituted by a recess formed by subjecting the diamond sintered body to a wear or dressing process.

  In one embodiment of the present invention, the average particle diameter of the diamond abrasive grains is preferably 25 μm or less.

  Here, in the above-mentioned Patent No. 3308246, a diamond blade for cutting a rare earth magnet is described, but it is preferable that the diamond content be 1 to 70 vol% and the average diamond particle diameter be 1 to 100 μm. I have. In Example 1, the average particle diameter of diamond was 150 μm. This is intended to improve the wear resistance of the cored bar with less bending and warpage.

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

  Japanese Patent Application Laid-Open No. 2003-326466 describes a blade for dicing ceramics, glass, resin, and metal, but it is preferable that the average particle size is 0.1 μm to 300 μm.

  Thus, with conventional blades, a relatively large diamond particle size is appropriate.

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

  In the case of 25 μm or more, the area ratio where the diamonds come into contact with each other is remarkably reduced, and although a part thereof is connected by sintering, most of the diamond has no sintering aid and becomes a space.

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

  Therefore, it is desirable that the particle size of diamond is 25 μm or less. However, as for the minimum particle diameter, the present state of trials is for fine-grained diamonds of about 0.3 to 0.5 μm, but it is unknown for ultrafine-grained diamonds smaller than that.

  In one embodiment of the present invention, the outer peripheral portion of the dicing blade is preferably 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 preferably 50 μm or less. More preferred.

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

  In one aspect of the present invention, the rotating mechanism is provided with a metal flange surface perpendicular to a rotation axis for rotating the dicing blade, 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 contacts 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 around the rotation axis.

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

  In still another aspect of the present invention, the dicing blade preferably cuts the work while rotating in a downcut direction.

  Further, in still another aspect of the present invention, a concave portion (a minute cutting blade) formed on the surface of the diamond sintered body is provided continuously along the circumferential direction on an outer peripheral portion of the dicing blade. Is preferred.

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

  In still another aspect of the present invention, it is preferable that the diamond abrasive has an average particle diameter of 25 μm or less.

  Further, in still another aspect of the present invention, it is preferable that an outer peripheral portion of the dicing blade is configured to be thinner than an inner portion of the outer peripheral portion, and a thickness of the outer peripheral portion of the dicing blade is 50 μm or less. Is more preferable.

  Further, in still another aspect of the present invention, a metal flange surface perpendicular to a rotation axis for rotating the dicing blade is provided, the dicing blade includes a reference plane portion on one side surface, and the reference plane portion includes It is preferable that the fixing member is fixed to the rotating shaft while 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 around the rotation axis.

  Advantageous Effects of Invention According to the present invention, it is possible to cut a work made of a brittle material in a state where the cutting depth of the dicing blade is set to be equal to or less than the critical cut depth of the work, and cracks and cracks occur. Without performing the cutting operation, the cutting process can be performed stably and accurately in the ductile mode.

Perspective view showing the appearance of a dicing device Front view of dicing blade FIG. 2 is a side sectional view showing an AA section in FIG. 2. Enlarged sectional view showing an example of the configuration of the cutting blade portion Enlarged sectional view showing another example of the configuration of the cutting blade portion Enlarged sectional view showing still another example of the configuration of the cutting blade portion Schematic diagram schematically showing the state near the surface of the diamond sintered body Diagram showing the state of the work surface when grooving was performed with a blade having an average particle diameter of diamond abrasive grains of 50 μm, showing a case where cracks occurred Sectional view showing a state where a dicing blade is attached to a spindle Diagram showing the result of comparative experiment 1 (silicon grooving) (this embodiment) Diagram showing the result of comparative experiment 1 (silicon grooving) (prior art) Diagram showing the result of comparative experiment 2 (sapphire grooving) (this embodiment) Diagram showing the result of comparative experiment 2 (sapphire grooving) (prior art) Diagram showing the result of Comparative Experiment 3 (when the blade thickness is 20 μm) Diagram showing the result of Comparative Experiment 3 (when the blade thickness is 50 μm) Diagram showing the result of Comparative Experiment 3 (when the blade thickness is 70 μm) Diagram showing the result of comparative experiment 4 (work surface) Diagram showing the result of comparative experiment 4 (work cross section) Diagram showing the result of comparative experiment 5 (work surface) Diagram showing the result of comparative experiment 5 (workpiece cross section) FIG. 7 shows the results of Comparative Experiment 6 (this embodiment). Diagram showing the result of Comparative Experiment 6 (prior art) Explanatory view schematically showing a state where dicing is performed using a blade having a cutting edge portion of a taper type on both sides. Diagram showing how burrs and chipping occur Explanatory drawing when geometrically calculating the maximum depth of cut when processing by moving the blade in parallel Figure showing the result of measuring the outer peripheral edge of the blade with a roughness meter Figure showing the result of measuring the outer peripheral edge of the blade with a roughness meter Diagram showing the surface condition of the outer peripheral edge of the blade (blade tip side) Diagram showing the surface condition of the outer edge of the blade (blade tip) Schematic diagram showing the blade tip cutting into the work material Explanatory diagram used to explain the thickness of the blade Illustration used to explain the thickness of the blade (when the thickness of the blade is larger than the thickness of the work) Explanatory diagram used to explain the thickness of the blade (when the thickness of the blade is smaller than the thickness of the work) Schematic diagram showing the appearance of the surface of the electroformed blade Schematic diagram showing the spacing of the abrasive grains according to the diamond abrasive content (when the abrasive content is 80% or more) Schematic diagram showing the spacing of the abrasive grains according to the diamond abrasive content (when the abrasive content is 70% or less) Sectional view of the outer edge of the blade when the cutting edge is formed by fiber laser (50 μm holes at 100 μm intervals) Front view of particle supply mechanism Side view of the particle supply mechanism Schematic diagram showing a configuration example of the blade processing apparatus according to the first embodiment Schematic showing a configuration example of a blade processing apparatus according to a second embodiment. Schematic showing a configuration example of a blade processing apparatus according to a third embodiment. Schematic showing a configuration example of a blade processing apparatus according to a fourth embodiment. Schematic diagram showing the appearance when applied to a conventional electroformed blade Schematic diagram showing the situation when 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 for transferring a cassette containing a plurality of works W to and from an external device, and a conveyance unit having a suction unit 14 and conveying the works W to each unit of the apparatus. It is composed of a unit 16, an imaging unit 18 for imaging the surface of the work W, a processing unit 20, a spinner 22 for cleaning and drying the processed work W, a controller 24 for controlling the operation of each unit of the apparatus, and the like. ing.

  The processing unit 20 is provided with a high-frequency motor built-in type air-bearing type spindle 28 having two blades 26 mounted at the ends thereof facing each other, and rotates at a high speed at a predetermined rotation speed and is independent of each other. Then, index feed in the Y direction and cut feed in the Z direction are performed. Further, the work table 30 on which the work W is mounted by suction is configured to be rotatable about the axis in the Z direction, and is configured to be ground and fed in the X direction in FIG. I have.

  The work table 30 includes a porous chuck (porous body) that vacuum-adsorbs 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 work W, which is a flat sample, is uniformly sucked over the entire surface in a state where the work is flattened by the porous chuck. For this reason, even if a shear stress acts on the work W during the dicing process, the work W is not displaced.

  Such a work holding method of vacuum-sucking 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 to a flat shape, it is difficult to define the reference plane of the work surface, and therefore it is difficult to set the depth of cut of the blade from the reference plane. Become. If a certain cutting depth of the blade cannot be set for the workpiece, a critical cutting depth at which one cutting edge constantly provides a stable cutting cannot be set, and stable ductile mode dicing is difficult.

  If the work is flattened, the reference plane of the work surface can be defined and the blade cutting depth from the reference plane can be set, so the critical cutting depth per cutting edge can be set and stable. This allows for ductile mode dicing.

  It should be noted that, instead of vacuum suction, a form in which the entire surface is adhered to a hard substrate may be used. Stable ductile mode dicing is possible if the surface can be defined even for a thin substrate with reference to the entire surface that is firmly bonded.

  FIG. 2 is a front view of the dicing blade. FIG. 3 is a side sectional view showing an AA 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-shaped blade, and has a central portion to be mounted on a spindle 28 of the dicing device 10. Mounting holes 38 are formed.

  The blade 26 is made of sintered diamond and has a disk-like or ring-like configuration. If the blade 26 has a concentric configuration, the temperature distribution is axially symmetric. If the temperature distribution is the same and axially symmetric, the shear stress accompanying the Poisson's ratio does not act in the radial direction. Therefore, the outer peripheral end keeps an ideal circular shape, and the outer peripheral end keeps the same plane, so that the rotation acts on the work in a straight line.

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

The outer peripheral portion of the blade 26 is a portion cut into the work W, and a cutting blade portion 40 formed to be thinner than the inner portion thereof is provided. In this cutting edge portion 40, a cutting edge (a minute cutting edge) formed of a minute dent formed on the surface of the diamond sintered body has a minute pitch (a minute pitch) along a circumferential direction of a blade outer peripheral end portion (outer peripheral edge portion) 26a. (For example, 10 μm).

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

  The cross-sectional shape of the cutting blade portion 40 may be formed in a tapered shape in which the thickness gradually decreases toward the outer side (front end side), or may be formed in a straight shape having a uniform thickness.

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

The cutting blade portion 40A shown in FIG. 4A is a one-side taper type (one-side V type) in which only one side surface portion is tapered and machined diagonally. The cutting edge portion 40A is, for example, the thickness T ₁ of the outer peripheral edge portion which is thinnest is 10 [mu] m, the taper angle theta ₁ of the portion side portion of the one side is processed into a tapered shape it has a 20 degrees. The thickness of the inner portion of the blade 26 (excluding an annular portion 36 described later) is 1 mm (the same applies to FIGS. 4B and 4C).

The cutting blade portion 40B shown in FIG. 4B is of a double-sided taper type (both V type) in which both side portions are slanted in a tapered shape. For example, the cutting edge 40B has a thickness T ₂ of 10 μm at the outermost end formed at the thinnest thickness, and a taper angle θ ₂ of a portion where both side surfaces are tapered 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. The cutting edge portion 40C, for example, the thickness T ₃ of the processed thinnest straight tip has a 50 [mu] m. The inner side portion (central side portion) of the straight tip portion is formed such that one side surface portion is tapered, 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 mutually bonded by the sintering aid 86 at a high density. On the surface of the diamond sintered body 80, a cutting edge (small cutting edge) 84 composed of a minute dent (recess) is formed. The recess 84 is formed by mechanically processing the diamond sintered body 80 to selectively wear the sintering aid 86 such as cobalt. Since the diamond sintered body 80 has a high abrasive grain density, the dent formed when the sintering aid 86 is worn becomes a small pocket, and there is no protrusion of a sharp diamond abrasive grain 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 transporting chips generated when the work W is cut, and also functions as a cutting edge 84 that cuts the work W. I do. This makes it possible to improve the dischargeability of chips and to control the cutting depth of the blade 26 with respect to the work W 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 formed of a diamond sintered body 80 formed by sintering diamond abrasive grains 82 using a sintering aid 86. For this reason, the sintering aid 86 is very slightly present in the gaps between the diamond sintered bodies 80, but the sintering aid is also diffused into the diamond abrasive grains itself, and in fact, the diamonds are strongly bonded to each other. It becomes a form to do. The sintering aid 86 is made of cobalt, nickel or the like, and has a lower hardness than diamond. Therefore, although the diamonds are bonded to each other, the portion where the sintering aid is rich is slightly weaker in strength as compared with the single crystal diamond. These portions are worn and reduced when the work W is processed, and become moderate recesses with respect to the surface (reference plane) of the diamond sintered body 80. Further, by subjecting the diamond sintered body 80 to a wear treatment, a dent in which the sintering aid has been removed is formed on the surface of the diamond sintered body 80. In addition, by dressing with a grinding wheel of GC (green carborundum) or cutting hard metal which is a hard brittle material in some cases, in addition to the sintering aid, some diamond is missing. Then, an appropriate roughness is formed on the outer peripheral portion of the diamond sintered body. By making the roughness of the outer peripheral portion larger than the diamond particle diameter, minute diamond abrasive grains are missing in one cutting edge, and the cutting edge is less likely to be worn.

  The depression formed on the surface of the diamond sintered body 80 works advantageously for processing in the ductile mode. That is, as described above, the recess functions as a pocket for discharging chips generated when the work W is cut, and also functions as the cutting edge 84 that cuts the work W. For this reason, the cut amount to the work W is naturally limited to a predetermined range, and a fatal cut is not given.

  Further, according to the blade 26 of the present embodiment, the number, pitch, and width of the dents formed on the surface of the diamond sintered body 80 are arbitrarily determined because they are integrally formed with the diamond sintered body 80. It can be adjusted.

  That is, the diamond sintered body 80 constituting the blade 26 of the present embodiment is one in which the diamond abrasive grains 82 are mutually bonded using the sintering aid 86. Therefore, there is a sintering aid 86 between the mutually bonded diamond abrasive grains 82, and a grain boundary exists. Since the grain boundary portion corresponds to a depression, the pitch and number of the depressions 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. In addition, the roughness can be adjusted by setting the abrasion 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 the dents formed on the surface of the diamond sintered body 80 are determined by the pitch of the grain boundaries formed according to the selection of the particle diameter of the diamond abrasive grains 82. It can be adjusted. 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, by selecting the particle size of the diamond abrasive grains 82 and appropriately adjusting parameters having good controllability such as abrasion treatment and dressing treatment, desired cutting along the crystal grain boundaries can be accurately performed. The spacing of the blades 84 can be achieved. Further, on the outer peripheral portion of the blade 26, the cutting edges 84 formed of dents formed on the surface of the diamond sintered body 80 can be arranged in a straight line along the circumferential direction.

  Here, as a comparison, a wheel used for scribing is similar to a wheel obtained by sintering diamond abrasive grains, but a difference is intentionally described in order to avoid confusion with a scribing wheel.

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

  First, as a decisive difference between the above document and the present invention, scribing of the above document is, as described in paragraph [0020] of the above document, a scribing line (longitudinal crack) formed on the surface of a substrate formed of a brittle material. ), And a vertical crack is generated in the vertical direction by scribing (see paragraph [0022] of the above-mentioned document). Cleavage is performed using this crack.

  In contrast, the principle of the present invention is completely different as a processing method for removing a material in a shearing manner without generating cracks and chipping. Specifically, since the blade itself rotates at high speed and acts almost horizontally on the work surface to remove the work, no stress is applied in the vertical direction of the work. In addition, the depth of cut is kept within the deformation range of the material, and processing is performed at a cut depth where cracks do not occur. As a result, a surface without cracks is obtained after processing. 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)
Scribing hardly penetrates into the material because it only cracks inside the material. Since only the ridgeline of the cutting edge acts, the cutting edge angle is usually an obtuse angle (see paragraph [0070] in the above-mentioned document). It is hardly conceivable that the angle is set to an acute angle or 20 degrees or less in consideration of a loss due to torsion.

  On the other hand, dicing penetrates into the material and removes the penetrated part, so the blade tip 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 advancing direction is considered. To some extent. At most, the apex angle is less than 20 degrees.

  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 processing mechanism, the side of the blade is ground more than the element that the blade tip advances. The volume to be used will increase. As a result, processing efficiency is reduced, and processing sometimes does not proceed. In the case of dicing, a cutting edge is formed on the outer periphery of the blade, and cutting is efficiently performed with the cutting edge at the tip. On the other hand, the blade side surface is improved in lubricity with the work, and is mirror-finished while reducing the amount of grinding. Is required. When the amount of grinding on the side surface of the blade increases, the amount of grinding on the side surface necessarily increases, and the cross section after cutting cannot be mirror-finished. Therefore, a straight shape is most desirable in dicing, but it is preferable that the blade be extremely small and V-shaped at least so as not to buckle the blade, and at most 20 degrees or less.

・ (Point of material composition)
In scribing, if the traveling direction changes in a state where the wheel is in contact with the work (biting state), the blade edge may be broken by torsional stress. Therefore, even if the same diamond sintered body is used, 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 percent of diamond is 75% or more, the hardness of the wheel itself increases, but the torsional strength decreases. Therefore, the diamond content is set relatively small.

  Dicing, on the other hand, proceeds linearly while the blade rotates at high speed to remove a certain amount of material. Therefore, no torsional stress is applied. Instead, when the diamond content is small, the apparent hardness decreases when cutting, so the reaction force from the work and the work elastically recovers within the cutting time of the cutting edge of the blade, In some cases, the predetermined depth of cut cannot be maintained. For this reason, in the case of dicing, the hardness of the blade is sufficiently larger than the hardness of the work so that the blade can be cut with a predetermined cut without rebound. In the ductile mode, within the deformation range of the material, in order to allow processing to proceed without allowing elastic recovery within the cutting edge action time during processing, surface hardness equivalent to single crystal diamond (about 10000 in Knoop hardness) is required, and Knoop About 8000 in hardness is required. As a result, a diamond content of 80% or more is required. However, when the diamond content is 98% or more, the ratio of the sintering aid is extremely reduced, so that the bonding force between diamonds is weakened, the toughness of the blade itself is reduced, and the blade itself is brittle and easily chipped. Therefore, the diamond content needs to be 80% or more, and considering the practical point, it is more preferable to be 98% or less.

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

・ (Point of wheel structure and reference plane)
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 the pin and the support frame, the pin portion (shaft portion) does not rotate. The inner diameter portion of the wheel serves as a bearing, and rotates by rubbing against the pin portion, which is a shaft, to form a vertical scribing line (vertical crack) on the surface of the material.

  In contrast, in the blade according to the present invention, the blade is coaxially mounted on the rotating spindle. The spindle and the blade are integrally rotated at a high speed. The blade must be mounted perpendicular to the spindle axis, and it is necessary to eliminate run-out due to rotation.

  Therefore, the blade has a reference plane. The reference surface present on the blade is fixed in contact with the reference end surface of a flange previously mounted vertically on the spindle. This ensures the perpendicularity of the blade to the spindle rotation axis. Only when this verticality is secured, the cutting edge formed on the outer peripheral portion by the rotation of the blade acts on the workpiece in a straight line.

  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 surface of the blade in the blade according to the present invention is, as described above, the side end surface (disk surface) of the blade facing the flange of the spindle. By setting the reference surface of the blade to the side surface (disc surface) of the blade, the blade rotates accurately with respect to the center of the blade. Therefore, even when the blade is rotating at a high speed, the cutting edge formed at the tip of the blade acts accurately at a predetermined height position defined by a constant radius position with respect to the blade center, and a predetermined height is obtained. The cutting edge acts only horizontally on the work surface without applying a vertical stress to the work, and the work is simply removed. Therefore, even if the work is a brittle material, no crack is caused by the normal stress on the work surface.

・ (Point of processing principle)
Whether the processing is performed by applying a crack in the vertical direction or processing without generating any crack is the difference between scribing and the dicing according to the present invention, which are crucially different principles.

・ (Role of outer peripheral groove)
In the scribing, a scribing line is formed by pressing only the surface by the vertical stress of the scriber. 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 cutting edge of the wheel abuts (bites) on the brittle material substrate (see paragraph [0114] ]reference). That is, the groove other than the groove can be provided with a scribing line to the extent that the material can cut into the material and cause a vertical crack. Therefore, it is more important how the crests between the grooves bite into the material than the grooves.

  On the other hand, in the case of dicing, the concave portion provided at the outer peripheral end portion serves as a cutting edge. The portion between the concave portions forms an outer peripheral contour, and is set so that the cutting edge provided therebetween has a critical cutting depth that does not cause cracks on the work surface. Therefore, in the case of dicing, it is necessary to form a cutting edge.

  In the case of scribing, the groove depth is formed to the extent that it gives a bite amount for making a scribing line, but in the case of dicing, it enters into the work and works with each cutting edge. Must be removed by grinding. For this reason, while the blade tip completely enters the work, the blade is not allowed to oscillate, and the cutting edge must be applied vertically to the work surface to a deep part of the material.

  In the case of the blade according to the present invention, the outer peripheral end has a cutting edge of a concave portion at a constant interval. As shown later, the cutting edge interval may be such that the critical cutting depth given by one cutting edge does not cause a crack. For that purpose, it is necessary to keep the cutting edge interval properly.

  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, and this is called a caster effect.

  With a dicing blade, the blade cannot penetrate the material, so the direction of the blade edge cannot be changed by 90 degrees. For example, if the cutting edge is changed while making contact with a straight shape or a dicing blade having an apex angle of 20 degrees or less, the blade will break.

  In the case of a diamond sintered body 80 sintered using a sintering aid 86 made of a soft metal, abrasion treatment or dressing treatment is most suitable as a method for forming a dent on the surface thereof. Not limited to For example, when a sintering aid such as cobalt or nickel is used, it is also possible to form a depression on the surface of the diamond sintered body 80 by partially dissolving it chemically by acid-based etching.

  In contrast, in conventional electroformed blades, the diamond abrasive grains themselves serve as cutting edges, but in order to adjust the pitch and width of the cutting edges, the degree of dispersion in which diamond abrasive grains are initially dispersed is adjusted. It is technically difficult to rely on That is, it contains a lot of ambiguity of dispersion of diamond abrasive grains, and cannot be substantially controlled. In addition, even if there is a portion where diamond abrasive grains are insufficiently dispersed and agglomerated, or if there is a sparse portion due to excessive dispersion, it is difficult to arbitrarily adjust these. As described above, with the conventional electroformed blade, it is impossible to control the arrangement of the cutting edges.

  Also, in conventional electroformed blades, it is not the present technology to artificially arrange diamond abrasive grains of micron order one by one, and it is almost impossible to efficiently arrange the cutting edges in a straight line. Impossible. In addition, with a conventional electroformed blade in which a dense portion and a sparse portion of the cutting edge are mixed and the arrangement of the cutting edge cannot be substantially controlled, it is difficult to control a cutting amount with respect to the work W, and in principle, ductility is increased. Mode machining cannot be performed.

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

According to the results of experiments conducted by the present inventor, when the average particle diameter of the diamond abrasive grains was 50 μm, cracks occurred when the wafer material was diced with a notch amount of 0.1 mm for SiC. Probably because of the diamond drop. In the case of sintering with a diamond average particle diameter of 50 μm or more, the area where diamond particles adhere to each other becomes small, and large particles are bonded together in a local area. Therefore, there is a disadvantage that the material is very weak in impact resistance and easily chipped in terms of the composition of the material. When diamond falls off in units of 50 μm or more due to local impact, a very large cutting edge is formed due to the falling off. In that case, a cutting depth greater than a predetermined critical cutting depth is given as an isolated cutting edge, and as a result, chipping and cracking are extremely likely to occur. Also, when the diamond of about 50 μm falls off, not only the cutting edge of the remaining portion becomes large, but the dropped diamond abrasive grain itself becomes entangled between the work and the blade, and may further crack. . With fine particles of 25 μm or less, the result that such cracks occur constantly has not been obtained.

  FIG. 6 shows a state of a work surface when grooving is performed by a blade having an average particle diameter of diamond abrasive grains of 50 μm, and shows a case where cracks are generated.

  Table 2 shows the results of evaluation of the incidence of cracks or chipping when grooving was performed using blades having an average particle diameter of diamond abrasive grains of 50 μm, 25 μm, 10 μm, 5 μm, 1 μm, and 0.5 μm. Show. The evaluation results show that the rate of occurrence 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)
・ Spindle speed: 20000rpm
・ Feeding speed: 1mm / s
・ Depth of cut: 100μm
・ Evaluation guideline: Evaluate whether there is chipping of 10μm or more. (Ideal to be completely free of chipping.)

  In addition, in sapphire, cracks occurred at a depth of 0.2 μm. Cracks were also generated in quartz and silicon by similar cuts.

  Further, when the average particle diameter of the diamond abrasive grains is 50 μm, it is also difficult to reduce the blade thickness (thickness of the outer peripheral edge portion) of the blade to 50 μm or less. 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 broken by a slight impact. 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, the same cutting is performed on each brittle material of SiC, sapphire, quartz, and silicon as when the average particle diameter is 50 μm. No cracks occurred. That is, in these brittle materials, cracks occur at submicron-order cuts when the average particle size of diamond abrasive grains is 50 μm, and when diamond abrasive grains with an average particle size larger than that are used, cuts are inevitable. And a fatal crack is caused. 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 still more preferably 5 μm or less) are used, the depth of cut can be suppressed and the depth of cut can be controlled with high accuracy. Becomes possible.

  The general processing conditions in this experiment are as follows: blade outer diameter 50.8 mm, wafer size 2 inches, incision 10 μm grooving, spindle rotation speed 20,000 rpm, table feed speed 5 mm / s.

  As a method of manufacturing the blade 26 configured as described above, a diamond fine powder is placed on a base mainly composed of tungsten carbide and put into a mold. Next, a solvent metal (sintering aid) such as cobalt is added as a sintering aid into the mold. Next, firing and sintering are performed under a high pressure of 5 GPa or more and a high temperature atmosphere of 1300 ° C. or more. As a result, the 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 the present embodiment can be obtained by taking out only the diamond sintered body and subjecting the blade base material to an outer peripheral wear treatment or a dressing processing into a predetermined shape. The diamond surface (excluding the cutting edge portion 40) of the cylindrical ingot is subjected to skiff polishing (scaif, a polishing disk) as a reference surface for eliminating runout during rotation, thereby obtaining a surface roughness (arithmetic mean roughness). Ra) It is preferable to process the mirror surface to about 0.1 μm.

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

  The conditions for the wear treatment are as follows.

・ Blade rotation speed: 10,000rpm
・ Feeding speed: 5mm / s
・ Workpiece processing target: Quartz glass (glass material)
-Processing time: 30 minutes-By the above processing, a cobalt sintering aid of about 1 to 2 µm was removed, and a dent was formed. Furthermore, the dent was further deepened by applying a very thin etching solution (weak acid type) thinly and treating in a dry environment without supplying pure water.

  The following conditions may be used as the dressing processing (wear processing).

・ Blade rotation speed: 10,000rpm
・ Feeding speed: 5mm / s
・ Workpiece: GC600 dressing whetstone (70mm □)
(GC600 means 600 grit (# 600) of silicon carbide abrasives. The particle size is based on Japan Industrial Standards (JIS) R6001.)
・ Processing time: 15 minutes ・ In this process, the cobalt sintering aid was slightly removed and a dent was formed.

  In the outer peripheral portion of the blade, it is preferable that the outer peripheral end portion and the side surface portion of the blade have different roughness. 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 abrasion treatment. In particular, the outer peripheral edge of the blade is slightly roughened because a large amount of work is removed while making a cut in the work material.

  On the other hand, the blade side surface is not actively removed, but only needs to be rough enough to cut out the groove side surface when the workpiece material comes into contact with the groove side surface. Also, if there is a protrusion on the side of the blade, it will cause cracks on the side of the groove.Therefore, while processing without forming a protrusion, the contact area with the side of the groove will be reduced, and even a little friction will occur. It is necessary to reduce the generation of heat due to heat. Therefore, it is desirable that the side portion is finely roughened.

  In conventional electroformed blades, etc., because the abrasive grains are hardened by plating, the entire surface has the same abrasive grain distribution, and as a result, the form of the abrasive grains on the outer peripheral edge of the blade and the side face of the blade is changed It could not be broadly divided. That is, it was not possible to clearly change the state of roughness between the outer peripheral end portion of the blade for cutting the work and the side surface portion which was slightly cut while rubbing the work.

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

  On the other hand, the outer peripheral portion of the blade is different from the side surface portion of the blade and needs to be cut and processed while processing the work. Such roughness can be formed on the outer peripheral portion by, for example, a pulse laser.

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

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

  Rather than forming notches with a material that hardens diamond by plating, such as electroforming, it is made of sintered diamond material, and by continuously forming minute notches at the outer peripheral edge of the disk However, each notch acts as a cutting edge.

  JP 2005-129741 A discloses, in a blade manufactured by an electroforming method, a method of forming a notch in an outer peripheral portion, but the notch in this case prevents a chip discharge function and clogging. A notch is provided as a function, and is not provided as a cutting edge. When manufactured by the electroforming method, diamond does not necessarily exist at the edge portion of the notch, but exists along with the binder, so that the binder wears with the processing, and thus acts as a cutting edge as a material. Not something.

  On the other hand, when the blade is made of a diamond sintered body, the tip of the cutting edge opened in the outer peripheral portion acts as a cutting edge as it is. In addition, since the diamond abrasive grain size is 5 μm smaller than the cutting edge size of 50 μm, it is possible for one diamond abrasive grain to chip inside one cutting edge and to grow small inside the cutting edge. Become. In the conventional electroforming method, the whetstone has the same size as the cutting edge because the diamond abrasive acts as the cutting edge as it is, 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 in the cutting edge can be changed, and as a result, sharpness can be ensured for a long time.

  Furthermore, by increasing the roughness of the outer peripheral edge of the blade relative to the roughness of the side surface of the blade, the blade side surface can be mirror-finished while shaving the workpiece with a fine rough surface while cutting at the outer peripheral edge of the blade. Can be. Conventionally, with an electroformed blade, it was difficult to change the roughness of the outer peripheral end and the roughness of the side part independently, and it was virtually impossible to do so. It is possible to form cutting edges at regular intervals on the outer peripheral end, and to make the side surfaces of the blades finely roughened. As a result, it is possible to perform mirror finish processing independently on the side of the work while securing the sharpness of the outer periphery and efficiently performing cutting.

  In addition, the configuration in which high-hardness diamond chips are embedded one by one only on the outer periphery of the blade (for example, Japanese Patent Application Laid-Open No. 7-276137), the cutting edges may be formed at equal intervals, but the integrated disk-shaped Because it is not formed by PCD, it applies a local effective shearing force to the workpiece without absorbing heat conduction points, geometric flatness and flatness continuity, and the impact of processing as described above. It is clear that the blade according to the present invention is completely different from the blade according to the present invention in that the processing is performed in the ductile mode.

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

  FIG. 7 is a sectional view showing a state where the blade 26 is attached to the spindle 28. As shown in FIG. 7, the spindle 28 is rotatably supported by a spindle main body 44 having a motor (high-frequency motor) (not shown) built therein and rotatably supported by the spindle main body 44. And a spindle shaft 46 disposed at the center.

  The hub flange 48 is a member interposed between the spindle shaft 46 and the blade 26, and is provided with a tapered mounting hole 48a and a cylindrical projection 48b. The hub flange 48 is provided with a flange surface 48c serving as a reference surface for determining the degree of perpendicularity of the blade 26 to the spindle shaft 46 (rotation axis). The blade reference surface 36a of the blade 26 abuts on the flange surface 48c as described later.

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

  The outer peripheral portion of the blade does not cause brittle fracture on the material surface at the time of cutting, so the cutting width needs to be narrow, and its thickness must be 50 μm or less.

  However, when manufacturing the entire blade including the blade reference surface portion with a thickness of 50 μm or less while keeping the thickness of the outer peripheral portion of the blade, a processing distortion when processing in the process of projecting the blade plane becomes a serious problem. In particular, when 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 the distortion between both side surfaces of the blade. If the blade is slightly warped, the outer peripheral end is very thin, and the blade is buckled and deformed to the originally warped side with a very small stress, so that the blade cannot be used as a result.

  For this reason, even if processing distortion remains on the blade surface, the portion forming the blade reference surface must not be thick enough to cause warpage due to the distortion. The thickness of the reference surface portion of the blade that does not cause warpage due to processing strain on a disk having a diameter of about 50 mm is at least 0.25 mm or more, preferably 0.5 mm or more. If there is no such thickness of the blade reference surface portion, a flat surface cannot be maintained as the blade reference surface. If a flat surface cannot be maintained, it is difficult to make the outer peripheral edge of the blade act on the work in a straight line.

  From the above, the blade 26 of the present embodiment needs to satisfy the following conditions.

  That is, since the blade reference surface 36a must maintain a flat surface even if the balance of the processing strain on both sides of the blade 26 is broken, the thickness of the reference surface portion must be at least 0.3 mm or more.

  On the other hand, the outer peripheral edge of the blade must be processed in an extremely small area so as not to induce cracks in the material. For that purpose, the thickness of the cutting blade portion 40 provided on the outer peripheral portion of the blade needs to be 50 μm 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 order to maintain flatness, and the inner peripheral part of the blade must be thickened to maintain flatness, while the outer peripheral part of the blade is It has to be thin.

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

  As a method of mounting 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 spindle shaft 46 formed in a tapered shape is fitted into the mounting hole 48a of the hub flange 48. Fix it. Next, with the mounting hole 38 of the blade 26 fitted into the projection 48b of the hub flange 48, the blade nut 52 is screwed into a thread formed at the tip of the projection 48b, so that the blade 26 is attached to the hub flange 48. Position and fix.

  When the blade 26 is attached to the spindle shaft 46 via the hub flange 48 in this manner, the perpendicularity of the blade 26 to the spindle shaft 46 is determined by the flatness of the flange surface 48c of the hub flange 48 and the blade reference surface 36a of the blade 26. It is determined by the flatness and the mounting accuracy in which both are superimposed. 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 that comes into contact with the flange surface 48c are flattened by, for example, mirror finishing, and It is preferable that the verticality is formed so as to be high precision. Thus, when the blade 26 is mounted on the spindle shaft 46 via the hub flange 48, the blade 26 is positioned high with respect to the spindle shaft 46 by positioning and fixing the blade surface 48 c and the blade reference surface 36 a 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 of the mounting hole 38 of the blade 26 and the projection 48b of the hub flange 48, the inner peripheral surface of the mounting hole 38 and the outer circumference of the projection 48b are determined. By increasing the processing accuracy of the surface, these coaxialities can be secured, and good mounting accuracy can be realized.

  As a result, high-precision cutting can be realized by ensuring high-precision attachment accuracy to the spindle shaft 46 in addition to the blade unit accuracy.

  That is, in order to work in the ductile mode, not only is the thickness of the cutting edge portion 40 of the blade 26 reduced, but also the cutting edge portion 40 is oriented in a direction perpendicular to the rotation axis (spindle axis 46) of the blade 26. Although high-precision mounting is required so that it can act on a substantially straight line, the required accuracy can be sufficiently satisfied.

  In the present embodiment, the hub flange 48 and the spindle 46 that support the blade 26 are made of stainless steel (for example, SUS304, SUS304 is a stainless steel based on the Japanese Industrial Standards (JIS)). (Based on industrial standards). On the other hand, the blade 26 is integrally formed by the diamond sintered body 80 as described above. That is, the blade reference surface 36a is configured to be 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 has heat due to the cutting process, or heat is present on the spindle shaft 46 side, the heat is first uniformly transmitted to the inside of the blade 26. That is, while the blade 26 is formed of a diamond sintered body 80 having a very high thermal conductivity, 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. It is made of stainless steel with low conductivity. For this reason, the heat generated therefrom is transmitted in the circumferential direction along the blade 26, is immediately uniformed in the circumferential direction of the blade 26, and has a radial temperature distribution. Only the diamond portion transmits heat immediately, and the stainless steel spindle shaft 46 and hub flange 48 do not transmit heat in terms of the cross-sectional area, etc., and there are few contact portions. As a result, the diamond portion has more uniform heat. Promoted and, in its uniform state, thermal equilibrium is assured.

In addition, since there is no member that hinders thermal expansion and there is no bimetal effect in 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 end of the blade acts on the workpiece W in a straight line.

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

  Next, a dicing method using the blade 26 of the present embodiment will be described. This dicing method can stably and accurately cut a brittle material such as silicon, sapphire, SiC (silicon carbide), or glass while plastically deforming the material without causing brittle fracture such as cracking or chipping. Is the way.

  First, the work W is taken out of the cassette placed on the load port 12 and placed on the work table 30 by the transport means 16. The surface of the work W placed on the work table 30 is imaged by the imaging means 18, and the position of a line to be diced on the work W and the position of the blade 26 are set to X, Y, and θ (not shown). The work table 30 can be adjusted and adjusted by the movement axis. When the alignment is completed and the dicing is started, the spindle 28 starts rotating, the spindle 28 moves down to the predetermined height in the Z direction by an amount to cut or groov the work W, and the blade 26 moves at a high speed. Rotate. In this state, the work W is processed and fed in the X direction shown in FIG. 1 by a moving shaft (not shown) together with the work 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 this time, the cutting depth (cutting amount) of the blade 26 with respect to the work W is set. By rotating the blade 26 requiring a large number of cutting edges on the outer periphery at a high speed, one cutting edge (small cutting edge) 84 must be set to be equal to or less than the critical cutting depth (Dc value). This critical depth of cut is the maximum depth of cut that allows cutting in 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 cause cracks.

  As can be seen from Table 3, when the work material is silicon, for example, the critical cut depth is 0.15 μm, so the cut depth of the blade 26 with respect to the work W is set to 0.15 μm or less. If the cutting depth exceeds 0.15 μm, cracks in the work material cannot be avoided.

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

  The peripheral speed of the blade 26 with respect to the work W (blade peripheral speed) is set to be sufficiently higher than the relative feed speed (working feed speed) of the blade 26 with respect to the work W. For example, when the rotation 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 while the rotation speed of the blade 26 is 53.17 m / s.

  The control of the cutting depth and rotation speed of the blade 26 and the relative feed speed of the blade 26 to the workpiece W are performed by the controller 24 shown in FIG.

  Dicing in such a ductile mode is repeatedly performed in a state where the depth of cut is set to be equal to or less than the critical depth of cut until the groove depth of the cutting line becomes the final depth of cut.

  When the dicing of the workpiece W along one cutting line is completed, the blade 26 is indexed and positioned on the next cutting line to be processed next, and is positioned 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 a predetermined number of cutting lines are completed, the work W is rotated by 90 degrees together with the work table 30, and the above-described cutting line is processed by the same processing procedure as described above. Dicing is performed along a cutting line in a direction perpendicular to the direction.

  In this way, when all dicing along all the cutting lines is completed, the work W is cut and divided into a number of chips.

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

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

・ Equipment: Blade dicing device AD20T (Tokyo Seimitsu)
・ Blade rotation speed: 20000rpm
・ Work feed speed (processing feed speed): 10mm / s
・ Cut depth: 30μm
・ Work: Silicon wafer (780μm thickness)
The results of Comparative Experiment 1 are shown in FIGS. 8A and 8B. 8A and 8B show the state of the work surface after the grooving process.

  As shown in FIG. 8A, when the blade 26 of the present embodiment was used, a cutting groove could be formed without generating cracks on the work.

  On the other hand, as shown in FIG. 8B, when a conventional electroformed blade was used, minute cracks occurred on the work surface. Cracks also occurred on the bottom surface of the cut 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 ductile mode without generating cracks, as compared with the case of using the conventional electroformed blade. I confirmed that I can do it.

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

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

  As is not clear from FIGS. 9A and 9B, it was confirmed that the same result as Comparative Experiment 1 for a silicon wafer was obtained even when the work was changed to a sapphire wafer.

[Comparative 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.

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

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

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

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

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

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

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

・ Equipment: Blade dicing device AD20T (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 cross section of the work after the grooving process. 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 off each fiber, so that a clean cross section of the fiber cannot be observed.However, the blade according to the present invention is sharpened without being entangled and tearing off each fiber. It is possible to obtain a cut surface having a suitable fiber end surface.

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

  Next, the reason why practical dicing can be performed even when the cutting in the ductile mode processing is performed by setting the cutting depth of the blade 26 to the work W to be equal to or less than the critical cutting depth (Dc value). I 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 (157,000 μm), about 15,700 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 so that one cutting edge does not crack the work W, and it is assumed that a single removal amount is 0.02 μm (20 nm) by the cut. In general, the critical cutting depth at which cracks do not occur, such as SiC, Si, sapphire, and SiO ₂ , is on the order of submicrons (for example, about 0.15 μm). Then, since there are 15,700 cutting edges at the outer peripheral edge of the blade, the processing can proceed in principle by about 0.314 mm (314 μm) per rotation of the blade. Assuming that the spindle for dicing is 10,000 rpm, the spindle rotates 166 times per second. Therefore, the cutting removal distance at the outer peripheral edge of the blade per second is 52.124 mm. For example, when the feed speed of the blade is 20 mm / s, the speed at which the work material is processed in the shear direction and removed is faster than the speed at which the work material advances while being pushed. That is, when cutting the work material, make a minute cut so that the work material is not broken, process the work material in the horizontal direction perpendicular to the direction of travel of the blade, and dispose of it. The removed portion has a form in which the blade advances. Therefore, there is no room for making a cut of 0.1 μm or more to the extent that a crack is generated, so that it is possible to perform cutting in a ductile mode processing region based on plastic deformation without causing brittle fracture. That is, by making the peripheral speed of the outer peripheral end portion (tip portion) of the blade by the rotation of the blade at a high speed relative to the processing target material larger than the feed speed of the blade to the processing target material, the processing in the ductile mode is performed. Can be performed.

  In practice, allow for some margin in consideration of the eccentricity of the blade, and with a blade diameter of φ50.8mm, while rotating at 20,000 rpm, machining at a feed rate of about 10mm / s No cracking of the material occurs.

  Next, a description will be given of the results of various studies for realizing processing in the ductile mode using the blade 26 of the present embodiment.

[About the cross-sectional shape of the cutting edge of the blade]
In the present embodiment, the cross-sectional shape of the cutting blade 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. It is preferably used.

  FIG. 14 is an explanatory diagram schematically showing a state in which dicing is performed using the blade 26 having the both-sided tapered cutting edge portion 40. First, as shown in portions (A) to (C) of FIG. 14, a tip portion 40 a provided at an arbitrary position of the cutting edge portion 40 of the blade 26 is deepest from the surface portion of the work W (lowest portion). Grinding of the workpiece W is performed while gradually moving the workpiece W to the point). Thereafter, as shown from (C) to (D) in FIG. 14, the distal end portion 40a of the cutting blade portion 40 gradually moves from the deepest portion of the work W toward the surface portion. 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 a region where the cutting edge portion 40 of the blade 26 cuts inward from the surface of the workpiece W, the upstream side in the blade rotation direction becomes the cutting portion 60 where the workpiece W is ground, while the downstream side has a blade side surface. A gap S is formed between the (side surface of the cutting blade portion 40) and the groove side surface, and the workpiece W is not ground, and a discharge portion in which chips ground by the upstream cutting portion 60 are discharged into the groove. 62.

  Generally, burrs and chipping occur when the blade is pulled out of the material by rubbing against the groove side surface. Therefore, for example, as shown in FIG. 15, when a straight type blade 90 whose side portions on both sides are machined in parallel in a straight shape is used, the blade tip (cutting edge) enters the inside of the work W from the outside. Until it escapes, the blade side constantly contacts the side of the cutting groove. Therefore, as compared with the double-sided tapered blade 26, when the blade tip comes out of the inside of the work W, the side surface of the cutting groove and the blade side surface are more easily rubbed, which causes burrs and chipping (FIG. 15). (D), (E)). Further, when an electroformed blade in which diamond abrasive grains are embedded is used, abrasive grains protruding from the side faces of the blade scratch the side faces of the groove, and this facilitates the generation of burrs and chipping on the side faces of the groove.

  On the other hand, according to the blade 26 having the both-sided tapered cutting edge portion 40, when the blade 26 comes out of the work W as described above, the gap S is generated between the blade side surface and the groove side surface. Therefore, burrs and chipping do not occur. Further, with the discharge of the chips, the heat generated during the grinding can be discharged together with the chips. This makes it possible to prevent the blade 26 from warping.

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

  Further, by performing the above-described cutting processing, it is possible to contribute to minimizing the generation of heat generated by friction caused by the contact between the blade side surface and the groove side surface. As a result, it is possible to suppress an increase in cutting resistance due to an increase in heat and to prevent welding of cutting chips to the blade 26. In addition, by leaving the cutting waste in the groove while creating the gap S in the process of extracting the blade 26 from the work W, the cutting waste is heated and discharged. Such cutting debris can be washed away in later washing. Further, since it is possible to suppress the heat generation of the blade 26 and the work W, it is possible to prevent such heat generation without supplying a large amount of water to the blade 26 and the work W, and to realize a dry environment. Processing becomes possible.

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

  First, in order to make a cut of 0.15 μm, it is desirable that the size of the cutting edge (small cutting edge) for making the cut has a large abrasive grain size of about one digit and a cutting edge interval. In the case where the cutting edge interval is three digits or more, it is difficult to make a minute cut in consideration of variation in the cutting edge interval.

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

Incidentally, D is a blade diameter, Z is a blade cutting edge number, N is the revolutions per minute of the blades, V _S is the circumferential speed of the blade (πDN), V _W is the feed speed of the workpiece, S _Z is per bladed blade And a is the depth of cut.

  Therefore,

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

Therefore,

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

Here, PaiDN clearly equal to the blade peripheral velocity _{V S.} That is, in 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.

Here, g _max : cutting depth per unit cutting edge, λ: cutting edge interval, V _ω : work feed speed, V _s : blade speed, a: blade cutting depth, D: blade diameter.

  From this, it can be seen that the spacing between the cutting edges is important in order to reduce the cutting depth per unit cutting edge to a certain value or less. Also, the rotation speed of the blade becomes important.

According to the relationship shown in the equation of g _max , even if V _ω : 40 mm / s, V _s : 26166 mm / s, a: 1 mm, D: 50 mm, λ: 25 μm, the cut amount is only about 0.027 μm, The cutting depth is 0.1 μm or less. In this range, the depth is equal to or less than the critical depth of cut, which is the range of ductile mode processing.

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

Furthermore, as a practical condition, under the condition that a 2 inch diameter blade (diameter 50 mm) is rotated at 10,000 rpm and processed, the work thickness is 0.5 mm, the work feed speed is 10 mm / s, and the blade outer peripheral part 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 substituted into the above equation, the critical depth of cut by one blade is 0.08 μm, which is still 0.1 μm or less. Therefore, if all the cutting edges ideally work on the workpiece removal processing without the blade being eccentric, 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 Processing can proceed without giving excessive cuts that cause cracks.

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

  Therefore, it is desirable that the cutting edge interval provided around the blade is 1 mm or less.

  On the other hand, the interval between the cutting edges around the blade is preferably 1 μm or more. If the average cutting edge interval is 1 μm or less, that is, if the cutting edge interval is on the order of submicrons, the critical depth of cut and the unit of depth of material removal become substantially the same. That is, both are on the order of submicron, but under such conditions, it is difficult for one cutting edge to actually reach the expected removal amount, and conversely, the processing speed is sharply reduced by the clogging mode.

  Under these circumstances, it is considered that the depth at which one cutting edge can be removed apart from the critical cutting depth of one cutting edge is impossible.

  The above idea holds when the cross-sectional area for cutting the work is constant. That is, in the case of a substantially flat sample, the blades are rotated at a high speed, the blade is set at a constant cutting depth with respect to the flat work, and the contents of the blade that cuts while sliding the work match.

  In the above equation, it is important that the critical depth of cut provided by one cutting edge depends on the interval between the cutting edges. The amount cut by one cutting edge affects the distance between the next cutting edge, and if there is a portion where the cutting edge interval is large in a certain portion, it indicates the possibility of causing a notch crack deeper than the desired critical depth of cut . 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 particle size (average particle size) of the diamond abrasive grains is large, the gaps are densely spread, and if the actual spacing between the abrasive grains is on the order of smaller than the particle size, the size of the abrasive grains is further increased. Cutting can be suppressed and controlled. Actually, diamond abrasives having an ideal particle size of about 1 μm to 5 μm are desirable.

  It should be noted that the particle size is not always the cutting edge interval. If truing is accurate, the spacing between the cutting edges may correspond to the grain size, but in the normally cut and dressed state the spacing between the cutting edges will be larger than the abrasive grain size.

  In other words, if strictly defined by the grain boundaries, the gaps present on both sides of one abrasive grain are interpreted as equivalent to the cutting edge, but in reality, some abrasive grains fall out as a lump and naturally become constant. A periodic cutting edge is formed. This makes it possible to form the cutting edge pitch by averaging the blades.

  17A and 17B show the results of measuring the outer peripheral edge of the blade with a roughness meter. 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.

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

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

  In this way, the blade tip has large irregularities in order to advance the work, whereas the blade side has a mirror-finished end face compared to the blade tip. Grind. Therefore, the tip of the blade is roughly formed for cutting and the side of the blade is finely formed.

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

  On the other hand, in the blade 26 of this embodiment, the diamond sintered body is configured to be very hard and high in strength because the sintering aid is melted into the diamond by sintering and the diamonds are firmly bonded to each other. You. Further, the diamond sintered body has a relatively large diamond content as compared with the electroformed blade (see, for example, JP-A-61-104045), and has a relatively large strength as compared with the electroformed blade.

  In addition, since most of the inside of the blade material is occupied by diamond, it is possible to make the other parts (including the sintering aid) smaller than the diamond volume. Even if the particle size is large, the gap between the diamond abrasive grains can be substantially on the order of microns.

  Further, the concave portion between the diamond abrasive grains plays a very important role in the present invention. Although diamond abrasive grains are very hard, some of the cobalt added as a sintering aid penetrates into diamond, but some remains between diamond abrasive grains. Since this part is slightly softer in hardness than diamond, it is easily worn in the cutting process and has a slightly concave shape. In other words, there is a portion sandwiched between diamonds, and by making the recess between them a minute cutting edge, it is intended to obtain a stable cut without giving an excessive cut. In addition, the minute cutting edge may act not only as a cutting edge between the diamonds but also as a cutting edge formed by the lack of diamond particles. The cutting edge interval may be set to an interval that does not exceed the critical cutting depth per one blade shown in the above equation.

For example, consider the case where diamond abrasive grains having a particle diameter of 25 μm are solidified by sintering. Here, for simplicity, it is assumed that the diamond abrasive is a 25 μm square cube. In order to bond the diamond abrasive grains, a 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 cube of 27 μm square. In that case, the volume% occupied by the diamond abrasive portion is about 78.6%. Therefore, if there is a diamond content of about 80% or more, even if the diamond abrasive grains of 25μm particle size, the gap between the diamond abrasive grains, that is, the particle spacing is substantially at most about 1-2μm, the dent The portion serves as a cutting edge (a minute cutting edge) for providing a cut. In addition, if the particle interval is about 2 μm, even if the particles of the pitch are pushed into the work material at the particle interval, the displacement of the work material becomes smaller by one digit or more than the interval of the diamond abrasive grains. That is, it is 0.15 μm or less. Further, assuming that the 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 about 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 an incision of 0.15 μm or less, and suppose that one third of the cutting edge, 0.03 μm, is removed per second. Then, with 2093333 micro-cutting blades, it is possible to remove about 6799 μm per second, and theoretically, it is possible to cut about 6 cm per second.

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

  In addition, even if the particle size of the diamond abrasive grains is not 25 μm or less, if the diamond content is 80% or more, the critical cut depth does not exceed the critical cut depth in terms of cutting and material removal. Therefore, it is possible to perform processing in a ductile mode without generating a crack.

  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 extremely high, and the individual diamond abrasive grains are cut to the size of the diamond abrasive grains. Acts as a blade.

  In addition, the distance between the diamond abrasive grains is much smaller than the particle diameter of the diamond abrasive grains, and the cut amount can be accurately controlled. As a result, the depth of cut is not greater than the predetermined initially intended depth of cut, which guarantees a constantly stable depth of cut during machining. As a result, it is possible to perform the ductile mode cutting without error.

  When the particle size is as large as about 25 μm, the content of diamond abrasive grains can be further increased. Some commercially available diamond abrasives have a content of about 93% (diamond content). If so, the proportion of the sintering aid is further reduced, that is, the gap between the diamond abrasive grains is actually very small.

  However, when using a diamond having a large particle size of 25 μm or more, as described above, the cutting edge interval is sufficient to perform ductile mode processing, but on the other hand, the blade thickness of the blade is 50 μm or less In some cases, such large abrasives cannot be manufactured.

This is because, for example, in the case of manufacturing with a blade thickness of 40 μm, at least two or more diamond abrasive grains must be provided in the blade cross section, but theoretically, two are not included and the number is 1.6.

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

  That is, when a cut is made in a wide range in a direction parallel to the blade surface (a surface perpendicular to the rotation axis of the blade 26) and removed, the deformation of the work material accompanying the cut is also spread in the vertical direction (cut depth direction). In other words, it is necessary to take the Poisson's ratio of the work material into consideration and to make the cut width somewhat finite. This is because, if the cut width is extremely increased, the material after deformation due to the Poisson's ratio will have an after-deformation in the longitudinal direction. As a result, a cut amount equal to or larger than the predetermined critical cut depth is formed, and as a result, the work W may be cracked.

  Here, the blade thickness (blade width) of the blade that can stably give a cut when the influence of the Poisson's ratio is considered will be examined. Table 4 shows the relationship between the Young's modulus of the brittle material and the Poisson's ratio.

  Here, it is assumed that one cutting edge cuts into the work material. In addition, the thin straight blade tip is not particularly sharpened arbitrarily, but if it is processed normally, the cross-sectional shape is assumed to be substantially semicircular.

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

  However, as shown in FIG. 19, when the substantially semicircular blade tip (blade outer peripheral end) is cut into the work material by 0.15 μm, the width is not uniformly displaced in parallel. In consideration of the rise of the outer circumference, it is possible to cut without being affected by the Poisson's ratio if the width of the arc is about 5 μm. That is, Rsin θ = 2.5 and R (1-cos θ) = 0.15.

  When this is calculated backward, the radius of the blade at the tip is about 25 μm, and the apex angle at which the above-mentioned 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. If it exceeds this, it will act on the material simultaneously at each point plane, sometimes leading to micro cracks.

  Note that if the curvature is greater than that, that is, if the blade thickness is about 30 μm, the cutting edge basically acts more locally than in the above state, so that the lateral width of the cutting edge basically affects the cutting depth. It has no effect and can be cut stably.

  Although the width of the blade has a viewpoint in performing ductile mode processing, the width of the blade is greatly related to the buckling strength of the blade alone.

  The width of the blade is also limited by the thickness of the work.

  Here, the relationship between the width of the blade and the thickness of the work will be described.

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

  When the blade thickness (blade contact area) 1 is larger than the workpiece thickness h, l> h, the portion where the blade contacts (the portion to be processed) becomes 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 state of bending 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 assumed that the distributed load acts simply as a beam problem.)

  In the case of a rectangular beam whose cross section is depth b and height h,

Therefore, the above equation is as follows.

  The maximum deflection is inversely proportional to the cube of the work thickness h at the center of the beam, and proportional to the cube of the blade contact area l.

In particular, in (l / h) ³ , when l / h is smaller than 1 at 1 / h, the flexure becomes much smaller, and when l / h is greater than 1, the flexure becomes much smaller. Become larger. Thus, there is a case where bending is caused by the shape of the relative thickness between the blade thickness (blade contact area) 1 and the work thickness h, and a case where bending is not caused.

  When the blade contact area is larger than the work thickness (l> h), the work bends in the contact area, but when the work bends, the vibration of the work due to the intermittent bending in the plane is vibrated. Occurs, and a predetermined cut cannot be achieved. As a result, a critical cut is given from the blade by the vertical vibration of the work, and a crack is generated on the work surface.

  Therefore, in particular, in the processing by the PCD blade of the present invention, in order to perform crack-free processing, 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, a predetermined cutting must be ensured with high precision by suppressing longitudinal vibration during machining of the work itself.

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

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

  In this case, the work does not bend in the contact area. On the other hand, a bending or compressive stress is applied in the contact area, but the deformation of the work is restricted by a Poisson's ratio in a laterally dense continuum. Therefore, it locally acts on the stress given by the blade as a reaction force from the work, and as a result, it is possible to perform processing at a predetermined cut without generating cracks.

[Comparison with conventional blades]
In the case of an electroformed blade as disclosed in Patent Literature 1, diamond is dispersed, and plating is performed from above. Therefore, diamonds are sparsely provided, and they have a protruding configuration. As a result, the protruding portion may naturally give an excessive cut, thereby inducing brittle fracture. Since the work material is also densely formed in the portion where the bottom and side portions of the groove are continuous, cracks are unlikely to occur immediately, but cracks and cracks are most likely to occur in portions where the blade comes off. This is similar to the occurrence of burrs when the blade comes off, because the work material is not continuous and free-standing.

  Further, in the case of the blade of Patent Document 2, since the film is formed by the CVD method, there is no protruding crack. However, it is impossible to control the arrangement of the cutting edges at the blade end, the plane state and the undulation of the side surface of the blade, and the like.

  In particular, as far as the blade side surface is concerned, the film thickness unevenness at the time of film formation directly corresponds to the blade thickness unevenness. In addition, since the surface of the film itself is a solid surface, the film may come into complete contact with the side surface of the material to induce frictional heat, or there may be a slight undulation, and the undulation may break the material.

  On the other hand, the blade 26 of the present embodiment is integrally formed of a diamond sintered body sintered by using a soft metal sintering aid, so that the outer peripheral edge of the blade and the side surface of the blade are subjected to wear treatment. It is possible to mold with. In particular, since the outer peripheral edge of the blade becomes a cutting edge, as described above, it is also possible to further change the wear treatment conditions in order to obtain a predetermined cutting edge. On the other hand, the role of the blade side is to remove chips first, but taking into account the contact with the side of the work, it is possible to stabilize the work It is desirable that the surface is roughened to a small extent.

  As described above, it is impossible for any of the techniques disclosed in the cited documents to design a desired surface state according to the state of the outer peripheral end portion of the blade and the side surface portion of the blade, and to manufacture such a surface.

  The blade used for scribing is not suitable for processing in ductile mode for the following reasons.

  That is, in scribing, the blade itself is not rotated, so that minute cutting edges that are equally spaced are not required. In addition, even if there is a cutting edge, if the cutting edge is not a small cutting edge along the crystal grain boundary of micron order but a large cutting edge, cracking will be given to the material in high-speed rotation dicing and it should be used at all. Can not.

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

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

  In addition, even if a scribing blade with a narrow cutting edge of 50 μm or less, particularly 30 μm or less is manufactured, the blade is received by a thin bearing, and since there is no reference surface received on a wide surface on one side of the blade, accuracy with respect to the workpiece is good. Straightness cannot be secured. As a result, the blade with a thin cutting edge is buckled and cannot be used.

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

  In order for the blade to cut a fixed amount into the work and to proceed as it is, the blade material needs to have a large strength with respect to the work material. If the blade material is simply made of a material that is softer than the work material, that is, a material having a small Young's modulus, the work material will not work even if the very thin blade tip acts on the work surface and the blade is advanced. If the member has a high elastic modulus, the surface of the work cannot be minutely deformed. If the member is forcibly deformed, the blade itself is buckled. Therefore, processing does not progress as a result. Here, the buckling load P of the long column supported at both ends is given by the following equation.

  E: Young's modulus, I: Second moment of area, l: Length of long column (corresponding to blade diameter).

  If the blade has a lower elastic modulus than the work material, if the processing proceeds while suppressing the buckling deformation of the blade, a second moment of area that does not cause buckling deformation is required. Have to be thick. However, particularly when processing a brittle material, if the blade thickness is larger than the work thickness, the work material surface is deformed and cracked. Therefore, the blade thickness must be smaller than the work thickness.

  As a result, the blade material must have a higher elastic modulus than the work 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 by a bonding material such as nickel and is nickel-based in material. Nickel has a Young's modulus of 219 GPa, for example, SiC is 450 GPa. The diamond abrasive grains electrodeposited on nickel are themselves 970 GPa, but since they exist individually and independently, they are eventually governed by the Young's modulus of nickel. Then, in principle, since the work material is highly elastic, it is necessary to cope with the problem by additionally increasing the thickness of the blade. As a result, it is necessary to increase the contact area by increasing the thickness of the electroformed blade, which causes cracks and cracks.

  On the other hand, in the case of the blade 26 of the present 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 work W, when the blade 26 is cut, not the blade 26 but the surface on the work W side is deformed. With the work W side deformed, it is possible to make a cut and process and remove it. In addition, the blade 26 does not buckle in the process. Therefore, even with a very sharp blade 26, processing can be performed without buckling.

  Table 5 shows the Young's modulus of each material. As is clear from Table 4, the sintered diamond (PCD) has a significantly higher Young's modulus than most materials such as sapphire and SiC. For this reason, it is possible to process even a blade thinner than the thickness of the work material.

  Next, the relationship between the hardness of the work material and the hardness of the blade material will be described.

  When the hardness of the blade material is lower than the hardness of the work material, for example, in the case of an electroformed blade, soft copper or nickel supports diamond. Although the diamond abrasive on the surface is very hard, the hardness of the nickel supporting the diamond abrasive underneath is extremely low as compared with diamond. Therefore, when an impact is given to the diamond abrasive grains, the nickel thereunder absorbs the impact. As a result, in the case of electroformed blades, the hardness of nickel becomes dominant, and as a result, even if hard diamond abrasive particles collide with the work material and try to cut the work, 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 certain number of rotations of the blade is applied to the diamond. At this time, the shock is momentarily absorbed by nickel, and the reaction force presses the work material with a large force on the diamond abrasive grains, so that 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 has a significantly higher hardness than hard brittle materials such as sapphire and SiC. As a result, even if a cutting edge (a minute cutting edge) formed of a concave portion formed on the surface of the diamond sintered body acts on the work material, the impact acts locally on the minute cutting edge portion as it is, and a sharp edge is formed. In combination with the tip portion, it is possible to precisely remove the minute portion.

  As described above, according to the present embodiment, the diamond sintered body 80 in which the content of the diamond abrasive grains 82 is 80% or more is integrally formed in a disk shape. The 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 is possible to control the cutting depth (cutting amount) of the blade 26 with respect to the work W with higher precision than the conventional electroformed blade. Thus, the work W can be moved relatively to the blade 26 while giving a constant cut depth to the work W without giving an excessive cut. As a result, it is possible to cut the work 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 work, thereby causing cracks and cracks. In addition, the cutting process can be stably and accurately performed in the ductile mode.

  In addition, the concave portion formed on the surface of the diamond sintered body 80 functions as a pocket for transporting chips generated when processing the work W. Thereby, the discharge performance of the chips is improved, and the heat generated during processing can be discharged together with the chips. In addition, since the diamond sintered body 80 has a high thermal conductivity, heat generated during cutting processing is not accumulated in the blade 26, and there is also an effect of preventing an increase in cutting resistance and warpage of the blade 26.

  Further, in the dicing process using the blade 26 of the present embodiment, it is preferable that the rotation direction of the blade 26 is the down-cut direction. That is, when the workpiece W is relatively moved with respect to the blade 26 while giving a cut to the workpiece W, as shown in FIG. 14, the rotation direction is such that the cutting edge of the blade 26 cuts into the workpiece surface. It is preferable that the dicing process is performed while rotating the blade 26.

  Further, in the dicing process using the blade 26 of the present embodiment, when the workpiece W is relatively moved with respect 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 in which the treatment is performed while feeding is preferred.

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

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

  The function of the outer peripheral portion of the blade is to remove chips while the cutting edge acts mainly to cut the cutting edge into the work and further advance the cutting.

  On the other hand, it is more important to adjust the side of the blade that has already been cut at the tip of the blade than the side of the blade, rather than cutting the work. For that purpose, it is necessary to grind the work side surface while smooth lubrication without cutting off the work side surface and the blade side surface, rather than the cutting edge acting positively on the blade side surface.

  As a method of smoothly lubricating the work side surface and the blade side surface without eroding the blade side surface, it is effective to apply fine particles to the dicing blade.

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

  Therefore, the action of fine particles on the side surface of the blade made of sintered diamond plays an important role as an effect of improving the lubrication effect between the blade and the work.

  When fine particles act on the side surface of a blade made of sintered diamond, as described above, the sintered diamond forms a concave part on the grain boundary part or on the uneven surface composed of natural roughness. Has many. Fine particles are taken into the recess. When the blade side surface is processed while being rubbed against the work, the fine particles accumulated in the concave portion formed by the diamond sintered body fly out and roll continuously between the blade side surface and the work side surface. This continuous rolling of fine particles is referred to as a "bearing effect", which prevents the blade from biting between the work surface and forms a lubricating effect between the blade and the work.

  The lubricating effect is not limited to the lubricating effect of simply preventing the blade and the work from biting. The rolling effect of the fine particles has a function of polishing the side surface of the work.

  The rolling of the fine particles causes the fine particles to rub against the side of the work, thereby polishing the side of the work.As a result, the side of the work has a clean mirror surface without leaving any grinding marks as if it were simply ground with fixed abrasive grains. Can be formed.

  As for such a lubricating effect, when grooves are formed on both side surfaces 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 of the portion where the blade enters the work. Then, the fine particles enter between the V grooves and roll along the V grooves with the rotation of the blade. As a result, the fine particles roll along the V-shaped groove between the work material and the blade, and a bearing effect appears. When the rolling effect appears, the fine particles are different from the fixed abrasive particles and the individual fine particles change the direction to some extent and act randomly, so there is no grinding streak in one direction, and the polishing effect on the side of the workpiece material Be demonstrated. As a result, it is possible to obtain a mirror surface from which grinding streaks have been removed.

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

  However, in the case of such a blade in which the fine particles to be rolled are preliminarily baked on the blade surface, 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. Also, it is difficult to stably and continuously supply fine particles.

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

  Further, with such easily peelable materials, the hardness of the blade itself that supports the substrate cannot be ensured, so that it is difficult to give a constant cut to the work even when 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 form in which diamond protrudes from the surface of the binder in some places. In other words, the surface has a form in which there are projections on a plane.

  Since the diamond is protruding, the critical depth of cut of the abrasive grains cannot be controlled as the binder forming the reference plane is removed. Therefore, a fatal crack is exerted on the side of the work. Even if the fine particles are allowed to flow as in the above embodiment, the work side surface may be mirror-finished even in some cases without a dent, but even if the fine particles act on the blade side surface to exert a polishing effect. On the other hand, in the case where the diamond protruding from the fixed abrasive grains is ground, a grinding streak still remains on the side surface of the work, and a potential crack due to the protruding enters. On the other hand, the effect of the fine particles that are mirror-finished while rolling is meaningless when used in combination with a processing phenomenon involving brittle fracture while exerting a crack.

  When the blade surface is viewed, the protruding diamonds are scattered in a plane. That is, there is no concave portion where the fine particles accumulate on the blade side surface.

  Even if the fine particles are stored between the diamond-dropped portions, that is, the binding material such as nickel, the hardness of the concave portion formed of a metal material such as nickel is lower than that of the material used for the fine particles. Even if the fine particles come out of the concave portion, the concave portion formed with a metal material such as nickel does not only have the concave portion functioning as a cutting edge, but the fine particle comes out of the nickel However, only the blade side of a soft metal such as abrasion wears, but there is almost no effect of polishing and removing the work. As a result, only the blade itself is gradually scraped off, and the effect of polishing the work cannot be expected.

  When the binder of the blade is worn by the fine particles, it means that the blade thickness changes even during the processing due to the polishing and removing action of the fine particles on the binder. For example, when the width of a groove is strictly controlled in the groove processing or the like, the blade cannot be used at all in a process where the blade is abruptly worn out, and is not meaningful as a blade to be processed.

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

  The fine particles accumulate in the recesses of the sintered body with respect to the blade formed of the diamond sintered body, and rub against the work from there, so that the fine particles are rolled out in a state of being brought out. Since the periphery of the concave portion is made of diamond, fine particles act on the edge portion of the concave portion made of diamond, and the work is polished.

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

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

(Method of supplying fine particles)
The method for supplying the 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 a method of supplying fine particles, there is a method in which fine particles contained in a liquid by a capillary structure are applied 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. The particle size and the material of the fine particles to be used may be appropriately optimized according to the work material and its purpose. For example, in the case of cutting for the purpose of removing a grinding streak on a cut side surface of a PC substrate or a copper substrate, a WA having a particle size of about 1 μm is suitable.

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

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

  It is desirable that the location where the liquid acts is placed just before the blade cuts into the work. Since the blade is rotating at a high speed and a part of the blade is blown off by the centrifugal force, it is desirable that the blade is just before entering the work.

  It should be noted that this does not make any sense if the substance applied to the blade is a liquid containing no fine particles. When a liquid containing no fine particles is applied, basically, the ability to polish the cut work side surface does not work. Therefore, it does not make sense to apply a liquid containing no fine particles.

  In addition, the liquid containing no fine particles has a low viscosity, and by including the fine particles, the interfacial tension acts between the fine particles and the liquid to increase the bonding force. As a result, the viscosity can be increased as a whole. If the viscosity can be increased, the liquid containing fine particles will not be blown off by the centrifugal force of the blade even when applied to the blade, and the liquid containing fine particles can be efficiently applied to the blade side surface or tip. is there.

  For example, there is a method of processing while supplying a slurry containing fine particles.However, in some cases, the work is strictly dried in a dry state because it wets other parts of the work other than the cutting place. Not applicable.

  In addition, when supplying a liquid slurry along the work, the slurry needs to have a viscosity low enough to flow along the work, instead of sticking to the work. However, in such a case, when the slurry comes into contact with the blade rotating at a high speed, there is a problem that the slurry is blown off. In particular, in the case of blades made of diamond sintered compacts, when the fine particles are effectively taken into pockets of such portions, the wind pressure and centrifugal force of the blade are dominant, and the fine particles stay on the blade. Sometimes it is difficult to do.

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

  It is very difficult to apply and attach solid fine particles to the side surface of the blade that rotates at a high speed, even if the fine particles normally act on the blade.

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

  First, by dissolving the fine particles in the liquid, the viscosity increases, the surface tension increases, and the gel can be formed. The liquid can enter between the fine particles to increase the surface tension.

  By dissolving the fine particles in the liquid in this manner, unlike the case where only the liquid is applied to the blade, it is possible to reliably act on the blade surface as a viscous liquid having a high surface tension.

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

  As the capillary structure member 104, any of a brush-like member, a brush-like member, and a foam member is used. That is, a structural member in which a small space continuously exists 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 pipe 102 and the peripheral side surface of the blade 26, and the tip thereof extends from both sides so that the tip is along the rotation direction of the blade 26. 26 is in contact with both peripheral 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.

  As shown in FIG. 25, a guide member 108 made of a rigid material is provided at the lower end of the liquid supply pipe 102 to guide the distal end of the capillary structure member 104 to the peripheral side surface of the blade 26. As a constituent material such as a brush-like member or a brush-like member as the capillary structural member 104, for example, a soft linear member such as a polyester-based wire or a 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 a high speed, the side surface of the blade 26 is not excessively damaged.

  Even in the case of the capillary structure member 104 using such a soft linear member, the distal end of 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. A blade rotating at a high speed that can guide the tip of the capillary structure member 104 made of a soft linear member so as to contact the blade 26 without being affected by the gravity of the liquid existing in the gap in the member 104. The liquid containing the fine particles can be reliably supplied to the peripheral side surface of the liquid crystal panel 26.

  As described above, according to the method for supplying fine particles in the present example, it is possible to apply a liquid containing fine particles to the side surface of the blade. This allows the capillary structure itself to be applied, which causes the liquid to act on the blade, to come into contact with the blade, and uses the interfacial tension acting between the liquid and the solid to carry fine particles contained in the liquid to the side surface of the work. Can be.

  In the method in which the liquid is blown against the blade rotating at high speed, the liquid is blown off on the blade, and as a result, it is not possible to make the fine particles act on the blade efficiently, but the liquid is applied to the blade and the interfacial tension is used. By doing so, it becomes possible to efficiently supply fine particles along the blade side surface.

  When a liquid containing fine particles is applied to the blade, the liquid adheres to the concave portion of the blade surface due to the interfacial tension of the liquid. Since the blade is rotating at a high speed in a vertical rotation, a part of the liquid attached to the blade is dried, and the heat generated by polishing by the fine particles can be removed by the heat of vaporization. Thereby, polishing can be performed without excessive heat generation even when polishing.

  In addition, it does not require cooling such as spraying water on the work by simply applying it to the blade. In some cases, it is possible to dry work the workpiece by only applying a small amount of liquid to the blade.

  As a result, physical polishing by the rolling of the fine particles can be more efficiently performed.

  Also, when the fine particles come out of the concave portion, the fine particles are caught and rolled between the edge portion of the concave formed by the diamond particles below and the work, so that the cutting of the fine particles rolling on the work is surely performed. The work can be surely polished while being given.

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

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

<Third example>
As still another example (third example) of a method of supplying fine particles, a thin sheet on which particles are applied is attached to a work, and the thin sheet is cut, whereby the fine particles on the sheet are naturally rolled up. There is a method in which fine particles act between the work and the blade.

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

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

(Blade processing equipment)
As described above, the blade 26 of the present embodiment is formed of a diamond sintered body (PCD) formed by sintering diamond abrasive grains for processing the work W in the ductile mode, that is, polycrystalline diamond. However, in order to stably and accurately cut a work made of a brittle material in a ductile mode without generating cracks or cracks, the surface of the polycrystalline diamond (the outer peripheral edge) is required. Section), it is necessary to form a continuous cutting edge along the circumferential direction. Therefore, it is desirable to always, or regularly or irregularly, process the blade 26 using a blade processing apparatus described later.

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

<First embodiment>
FIG. 26 is a schematic diagram illustrating a configuration example of the blade processing apparatus according to the first embodiment. As shown in FIG. 26, the blade processing apparatus 200A according to the first embodiment includes a blade processing unit 202 that processes the blade 26. The blade processing unit 202 is an example of a cutting edge generating unit, and selectively removes crystal grain boundary portions on 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 processing unit 202 generates a discharge by applying a voltage between the processing electrode 204 disposed to face the polycrystalline diamond 26a and the polycrystalline diamond 26a and the processing electrode 204. A power supply unit 206 (voltage application unit), a nozzle 208 (working liquid supply unit) that injects and supplies a working liquid between the polycrystalline diamond 26a and the processing electrode 204, and a control that controls each unit of the blade processing unit 202 (Not shown).

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

  Here, when the discharge oil is used as the working fluid, a part thereof is changed to the thermally decomposable carbon, and the polycrystalline diamond is more easily desorbed, so that not only the crystal grain boundaries but also the diamond abrasive grains themselves fly greatly. . An object of the present invention is to form ducts at substantially equal intervals to efficiently perform ductile mode processing, but sometimes diamond abrasive grains themselves are largely detached, and the formation of equally spaced cutting edges is hindered. Instead, the polycrystalline diamond may be flattened and no cutting edge may be formed.

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

  Therefore, in consideration of the cleanliness of the work surface, the discharge oil cannot be used as it is, which is a great hindrance when applied in the discharge machining for the purpose of cutting edge regeneration for polycrystalline diamond in the present invention. .

  The processing electrode 204 is arranged 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 a wire collection unit, and moves between the wires. Electric discharge machining is performed with the wire electrode facing the polycrystalline diamond 26a as a workpiece. The shape of the processing electrode 204 is not particularly limited as long as a discharge can be generated between the processing electrode 204 and the polycrystalline diamond 26a.

  Further, it is preferable that the processing electrode 204 is formed of a metal electrode or an electrode material (for example, carbon or the like) which elutes into a processing liquid and becomes a metal ion. As described above, a non-conductive liquid is used as the working fluid. However, in order to promote local electric discharge machining due to electric field concentration, the electrode material of the working electrode 204 is changed to a non-conductive material on the other side (in this example, Polycrystalline diamond). In order to attach the electrode material, it is desirable that the electrode material is ionized, and the ionization causes a small amount of the electrode material to be dissolved in the working fluid and adhere to the polycrystalline diamond on the other side. Thereafter, a selective erosion effect is produced by the electric field concentration effect discharge.

  The distance between the polycrystalline diamond 26a and the processing electrode 204, that is, the discharge gap (distance between the electrodes) needs to be several μm to several tens 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 provide 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 an electrode moving means for moving the machining electrode 204, and adjusts the discharge gap by changing the position of the machining electrode 204 with respect to the polycrystalline diamond 26a by the electrode moving means. As the electrode moving means, for example, a driving device such as a piezoelectric element, a linear motor, or a motor is used. Note that, instead 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 including the discharge gap adjusting means, the discharge gap can be maintained in an appropriate state, and stable electric discharge machining can be performed. Further, although the wear (wear) of the machining electrode 204 may progress with the electric discharge machining, the electric discharge gap can be adjusted according to the degree of wear of the machining electrode 204, so that the machining accuracy of the electric discharge machining is improved. It becomes possible. In addition, the number of replacements of the processing electrode 204 can be reduced, and the work and cost that occur with the replacement of the processing electrode 204 can be reduced, and the working efficiency can be improved.

  Further, in the aspect including the discharge gap adjusting means, the aspect including the discharge gap detecting means for detecting the discharge gap is more preferable. In this case, the discharge gap adjusting unit 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 unit, thereby setting the discharge gap in advance. Adjust to the set value. This makes it possible to automatically adjust the discharge gap in accordance with the degree of wear (wear) of the machining electrode 204 caused by electric discharge machining, so that machining accuracy can be increased and electric discharge machining can be stabilized. It becomes possible.

  As the discharge gap detecting means, for example, there is a mode constituted by a pole voltage detecting means for detecting a pole voltage generated between 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 inter-electrode voltage detected by the discharge gap detecting means (inter-electrode voltage detecting means). Note that the discharge gap detecting means is not limited to the above-described embodiment, and may employ, for example, various optical, magnetic, and electrical methods.

  Further, in the blade processing apparatus 200A of the present embodiment, since the electric discharge machining is performed while rotating the blade 26, the abrasion of the machining electrode 204 progresses, and a part of the machining electrode 204 may be locally unevenly 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 adopted.

  That is, when the machining electrode 204 is partially worn, the 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 relatively to the machining electrode 204 while rotating. Thereby, the surface of the processing electrode 204 is processed. Thereby, the surface of the processing electrode 204 can be corrected and uneven wear of the processing electrode 204 can be eliminated. According to this aspect, it is possible to regenerate the machining electrode 204 worn due to the electric discharge machining, so that the number of times the machining electrode 204 needs to be replaced can be reduced, and the machining electrode 204 occurs when the machining electrode 204 is replaced. 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 26a and the other electrode terminal connected to the processing electrode 204, and applies a pulse voltage between the polycrystalline diamond 26a and the processing electrode 204. As the polarity at the time of electric discharge machining, a mode 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 processing electrode 204 are such that a discharge is generated between the polycrystalline diamond 26a and the processing electrode 204. It is appropriately set according to the material, the distance between the electrodes, the type and the supply amount of the processing liquid, and the like.

  Preferably, the power supply unit 206 applies a bipolar pulse voltage or an AC 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 crystal grain boundary portion on the surface of the polycrystalline diamond 26a while alternately inverting the polarity between the polycrystalline diamond 26a and the processing electrode 204. Adhesion and desorption of the material are repeated, and efficient and local electric discharge machining becomes possible.

  In the blade processing apparatus 200A configured as described above, after moving the blade 26 to a predetermined position (electric discharge processing position) before and after or during processing of the work W, the blade 26 is rotated while being driven. A discharge is generated by applying a pulse voltage between the polycrystalline diamond 26a and the processing electrode 204 while supplying a processing liquid between the polycrystalline diamond 26a and the processing electrode 204. As a result, an electric field is concentrated on the crystal grain boundary portion on the surface (the outer peripheral end portion) of the polycrystalline diamond 26a to cause erosion, and the eroded portion acts as a cutting edge. As a result, it is possible to generate a continuous cutting edge along the circumferential direction on the surface of the polycrystalline diamond 26a. Thereafter, when processing the work W, the blade 26 is moved to the original position (work processing position), and the blade 26 is driven to rotate to process the work W.

  In the present embodiment, as an example, the mode in which the electric discharge machining is performed offline before or after the processing of the work W or during the processing is shown. However, the present invention is not limited to this. Can be preferably adopted. According to this aspect, the work is performed on the workpiece W in a state where a new cutting edge is always generated on the surface of the polycrystalline diamond, so that the processing efficiency and the processing accuracy can be improved.

  Next, the mechanism of cutting edge formation 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-mentioned 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 depending on the degree of crystal growth, and the size and interval of the crystal grain boundary cannot be arbitrarily adjusted. Crystallinity changes greatly depending on the state. If such a crystal 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 case of the present invention, electric discharge machining is used for the purpose of forming a cutting edge on the surface of polycrystalline diamond. In addition, as the cutting edge, a crystal grain boundary portion present at a certain interval is used as a cutting edge in order to set a certain cutting depth. In polycrystalline diamond, diamond abrasive grains are densely spread in a 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. Further, in order for the diamond abrasive grains to bond with each other, the content of the diamond abrasive grains must be at least 70 vol% or more.

  If the diamond abrasive grains are spread as described above, 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 cutting edge portions, and cutting edges at equal intervals are formed for each crystal grain (diamond abrasive grain). As for the equally-spaced cutting edges, the cutting depth that one cutting edge cuts is automatically set within a certain range, so that the predetermined cutting is stably secured and a fatal crack is applied to the work. It does not cut like this.

  In order to use the crystal grain boundary portion of polycrystalline diamond as a cutting edge, it is important that the crystal grain boundary portion is eroded relatively deeper than the crystal grain portion (diamond abrasive grains). The intragranular portion of the crystal grain is a single crystal, but the crystal grain boundary portion is discontinuous even if a part thereof is crystallized, so that the portion is inferior in strength and easily eroded selectively. An electric field concentration is caused in the crystal grain boundary portion to selectively erode, and the crystal grain boundary is used as a continuous cutting edge aggregate having cutting edges.

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

  Further, in order to form a continuous cutting edge aggregate for forming a constant cutting edge interval, it is necessary that the cutting edges themselves exist continuously. For that purpose, the cutting edge needs to be a closed loop. If it is interrupted on the way rather than in a closed loop, the cutting edge coming after the interruption will give a fatal cut. When a closed loop cutting edge is formed and the cutting edge is rotated on it, the cutting edges at an infinitely constant interval will act, and each cutting edge will be continuously processed within a certain cutting range. It becomes possible.

  Note that the mechanism by which the cutting edges at a constant interval result in one cutting edge being equal to or less than the critical cutting depth has already been described, and the description is omitted here.

  Here, in the case of conductive diamond formed by a CVD method, when a dopant is used for diamond, there is a problem that it is difficult to cause an electric field concentration only in a crystal grain boundary portion, and it is difficult to form a cutting edge based on the crystal grain boundary. . This does not necessarily mean that it is not suitable to include dopants in general, but in order to perform electrical discharge machining by relatively clearly separating the crystal grain boundaries from the crystal grains, the diamond abrasive grains themselves must be a dielectric material. 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 forming the cutting edge.

From the above, requirements required for the blade to form a continuous cutting edge aggregate are listed below. However, desirable parts are not essential requirements.
-A diamond sintered body (sintered diamond), that is, a polycrystalline diamond is desirably formed of a sintered body in which diamond abrasive grains are spread at high density. At least 70 vol% or more of the portion occupied by the abrasive grains in the volume is required.
-As a sintering aid for polycrystalline diamond, it is preferable to use a conductive sintering aid.
When the conductive sintering aid is used, electric field concentration occurs particularly in the crystal grain boundary portion where the concentration is high, and the sintering aid is selectively consumed, thereby contributing to the formation of the cutting edge by the erosion action.
-It is better that the polycrystalline diamond does not contain much dopant or the like. The dopant sometimes blurs the boundary between the crystal grain boundary and the crystal grain portion.
-The cutting edge formed at the outer peripheral end of the blade must be a closed loop. In the case of a disk-shaped blade, the cutting blades at constant intervals act constantly as the blade rotates, and the machining proceeds stably with a cutting depth within a certain range.
-It is desirable that the blade has a disk-like and integral configuration. Even in forming the cutting edges at regular intervals, the uniformity of the base material is important, and it is preferable that the base material be an integral body over one circumference.

  As described above, according to the blade processing apparatus 200A according to the first embodiment, the processing liquid is supplied between the polycrystalline diamond 26a and the processing electrode 204 while the processing liquid is supplied between the polycrystalline diamond 26a and the processing electrode 204. To generate a discharge by applying a voltage to the surface of the polycrystalline diamond 26a, an electric field is concentrated on the crystal grain boundary portion (conductive auxiliary agent) and selectively removed. 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 and cracks.

  The polycrystalline diamond 26a constituting the blade 26 is not limited to the one obtained by sintering diamond abrasive grains using a conductive sintering aid (for example, nickel or cobalt). The blade processing apparatus 200A can be applied to a blade made of polycrystalline diamond containing no agent. Also in this case, similarly to the case of applying to the polycrystalline diamond 26a containing the conductive sintering aid, an electric field concentration occurs at the crystal grain boundary portion on the surface of the polycrystalline diamond to cause an 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 processing apparatus according to the second embodiment. In FIG. 27, the same reference numerals are given to the same components as those in the above-described 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 part 212 is provided inside the processing tank 210, and the counter electrode 204 is held on the upper surface of the electrode holding part 212. The method for holding the counter electrode 204 is not particularly limited. For example, the counter electrode 204 is held on the upper surface of the electrode holding section 212 by using vacuum suction or mechanical means.

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

  The 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 processing 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 mounted on the spindle shaft 46 is set to the anode via the power supply brush 214, and the processing electrode 204 is set to the cathode via the power supply terminal 216. Note that, similarly to the above-described first embodiment, it is preferable that the power supply unit applies a bipolar pulse voltage or an AC voltage in which the polarity between the polycrystalline diamond 26a and the processing electrode 204 is alternately inverted.

  Further, the blade processing apparatus 200B includes a servo mechanism 218 (discharge gap adjusting means) for controlling an interval (discharge gap) between the polycrystalline diamond 26a forming the blade 26 and the processing electrode 204. The servo mechanism 218 controls the discharge gap such 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 processing electrode 204 relative to the blade 26, for example, only the processing electrode 204 may be moved in the processing tank 210 without changing the position of the processing tank 210, or the processing tank 210 may be moved. The processing electrode 210 may be moved together with the processing 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 processing electrode 204 may be moved.

  The blade processing apparatus 200B includes a nozzle 204 that supplies a processing liquid into the processing tank 210. The nozzle 204 is open at a position near the processing portion between the polycrystalline diamond 26a and the processing electrode 204, and supplies the processing liquid locally to the processing portion during electric discharge machining. Thereby, a flow of the working fluid can be created in a working portion between the polycrystalline diamond 26a and the working electrode 204, so that electric discharge machining can be performed without being affected by impurities generated by electric discharge machining. .

  According to the blade processing apparatus 200 </ b> B according to the second embodiment, electric discharge machining is performed in a state where the tip portion (outer peripheral end portion) of the blade 26 is immersed in the processing liquid stored in the processing tank 210 while rotating the blade 26. Therefore, a cutting edge can be efficiently generated on the blade 26 in a stable environment.

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

  As shown in FIG. 28, a blade processing apparatus 200C according to the third embodiment incorporates a function as a dicing apparatus, and includes a work processing section 302 for processing a work W and a blade processing for processing a blade 26. And a section 304.

  The work processing section 302 has basically the same configuration as the processing section 20 of the dicing apparatus 10 shown in FIG. That is, the blade 26 is mounted on the tip of the spindle 28, and the blade W moves relative to the workpiece W to process the workpiece W. After setting a predetermined cut in the work W, the blade 26 slides to perform processing. By properly selecting the number of rotations 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 of cut or more, and ductile mode processing is performed.

  The blade processing unit 304 is disposed at a position adjacent to the work processing unit 302. The blade 26 is configured to be movable between the workpiece processing unit 302 and the blade processing unit 304 by a spindle moving mechanism (not shown) while being mounted on the tip of the spindle 28. FIG. 28 shows a preferred embodiment in which the workpiece processing unit 302 and the blade processing unit 304 are arranged side by side from the upstream side along the direction of movement of the blade 26 relative to the workpiece W (leftward in the figure). However, the present invention is not limited to this. For example, the workpiece processing unit 302 and the blade processing unit 304 may be provided in parallel in a direction parallel to the rotation axis of the blade 26.

  The blade processing section 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 section 206, and a nozzle 208.

  The processing electrode 204 is disposed so as to face the polycrystalline diamond 26a constituting the blade 26 when the blade 26 has moved to the blade processing unit 304. The processing electrode 204 is connected to a 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 generates a discharge by applying a pulse voltage between the polycrystalline diamond 26a and the processing electrode 204. FIG. 28 shows an example in which the power supply unit 206 is configured by a DC power supply, 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 supply and the polarity between the polycrystalline diamond 26a and the processing electrode 204 is alternately reversed.

  The nozzle 208 is for jetting and supplying a processing liquid between the polycrystalline diamond 26a and the processing electrode 204, and it is preferable to use ultrapure water as the processing liquid as in the first embodiment. is there.

  According to the blade processing apparatus 200C according to the third embodiment, after moving the blade 26 from the work processing unit 302 to the blade processing unit 304, the blade processing unit 304 configures the blade 26 while rotating the blade 26. While supplying a processing liquid between the polycrystalline diamond 26a and the processing electrode 204, a pulse voltage is applied between the polycrystalline diamond 26a and the processing electrode 204 to generate a discharge. As a result, a cutting edge is formed at a crystal grain boundary portion on the surface (outer peripheral end) of the blade 26, and a cutting edge is generated and regenerated at substantially equal intervals for each densely laid diamond abrasive grain.

<Fourth embodiment>
FIG. 29 is a schematic diagram illustrating a configuration example of a blade processing apparatus according to the fourth embodiment. Note that, in FIG. 29, the same reference numerals are given to the components common to the above-described drawings.

  As shown in FIG. 29, a blade processing apparatus 200D according to the fourth embodiment incorporates a function as a dicing apparatus, similarly to the above-described third embodiment. It has a configuration in which the part 302 and the blade processing part 304 are integrated.

  As a specific configuration, the blade processing apparatus 200D includes a blade cover (flange cover) 316 surrounding the blade 26. The blade cover 316 is fixed to the spindle 28 side, and when the blade 26 moves with respect to the work W, the flange cover 316 moves integrally with the blade 26.

  Inside the blade cover 316 (blade-facing surface), a processing electrode 204 facing the blade 26 with a gap is attached.

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

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

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

(Unipolar and bipolar)
Each of the blade processing apparatus 200C according to the third embodiment and the blade processing apparatus 200D according to the fourth embodiment employs, as an example, a mode in which elution or discharge from the blade surface is promoted using the blade side to be processed as an anode. However, not only a mode of applying a unipolar pulse voltage but also a mode of applying a bipolar pulse voltage or an AC voltage is preferable. According to such an embodiment, the step of attaching metal ions to the blade surface and the step of detaching metal ions alternately proceed to efficiently form a cutting edge by discharging the crystal grain boundary portion on the surface of polycrystalline diamond, or A cutting edge is formed by partial electrolytic elution. In particular, since the electric field concentration occurs at the crystal grain boundary portion, the deposition proceeds more selectively at the crystal grain boundary portion than at other portions, and at the same time, the desorption occurs selectively.

(Insulation configuration)
Further, as a configuration for attaching the blade to the spindle, it is preferable that the blade is insulated from the spindle. There are several possible 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 shaft portion is formed of ceramics, and the shaft is insulated.

  Another method is to insulate a flange for fixing the blade and the blade surface. This is, for example, a method of alumite-treating the end surface supporting the blade to eliminate conduction. The blade may be supplied with power by a simple brush contacting the shaft.

(Effect of the same spindle)
It is desirable that the part for performing the work processing and the part for performing the blade processing (cutting edge generation / cutting edge regeneration) be respectively performed in a state where the blade is attached to the same spindle. The blade processing device 200C according to the third embodiment and the blade processing device 200D according to the fourth embodiment are both mounted on the same spindle 28. If blade processing is performed with a blade mounted on one spindle and then mounted on another spindle to process a workpiece, there is almost always a mounting error. As an installation error, for example, when the coaxiality is deviated, the cutting edge at the blade tip does not act on the work at the set cutting edge interval. Since one-sided contact occurs according to the amount of axial deviation, in principle, it does not become ductile mode processing in which all equally-spaced cutting edges act stably. Cracks occur on the work surface due to the intermittent action of the cutting edge. Also, there is a considerable problem of run-out. In particular, in the case of a thin blade, it is important to make the tip of the blade work in a straight line in order to make the cutting edges at regular intervals work.However, if the blade has some runout, it does not work in a straight line and Because of the meandering, in principle, the cutting edges at a constant interval are not constantly acting, and as a result, the ductile mode machining does not progress. When performing blade processing with the blade processing apparatus 200C according to the third embodiment or the blade processing apparatus 200D according to the fourth embodiment, the electric discharge machining is performed by rotating the blade and acting on the opposing electrode. Even if there is 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 mounting error problem.

(Effect of slide by constant cut)
In the blade processing apparatus 200C according to the third embodiment and the blade processing apparatus 200D according to the fourth embodiment, the work is processed while giving a notch of a fixed depth to the blade and sliding so as to maintain the notch. It is desirable. As shown in the above-mentioned formula, it is possible to set one cutting edge to be stable and not to exceed a predetermined cutting amount, and to perform ductile mode processing.

(Effects of environment and contamination)
Further, when processing the tip of the blade with the same spindle as described above, it is desirable to set the work processing portion and the blade processing portion at relatively close positions.

  2. Description of the Related Art 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 dislike contamination. That is, if a contaminant is present, it adheres to the surface of the work and penetrates into the material, thereby ruining the properties of the work material itself.

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

Similar to cutting oil, discharge oil and the like often hinder use in terms of contamination. In processing semiconductor and electronic component materials, pure water is usually used for processing. Pure water does not adversely affect the work in terms of contamination.

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

(Effect of using pure water as processing fluid)
It is desirable to use pure water as the working fluid (discharge fluid). Pure water is a nonconductor liquid, and the blade to be processed is also a polycrystalline diamond, which is a material close to a nonconductor. In such a configuration, an extremely large electric field concentration occurs particularly at the crystal grain boundary portion, and only the cutting edge portion is selectively processed by erosion. This makes it possible to form cutting edges at regular intervals along the diamond abrasive grains.

(Effect of using running water)
In addition, it is desirable that the working fluid be run under running water in order to exhibit the effect as a continuous nonconductive fluid. This is because it is necessary to constantly maintain a stable insulating state as a discharge environment. In order not to use the liquid once used again, it is desirable to use a one-pass liquid, for example, to flow the liquid at an angle along a slightly inclined electrode.

(Effects of using metal electrodes as electrodes)
In addition, pure water is used as the processing liquid, and the running water is used to stabilize the environment. On the other hand, the counter electrode is preferably a metal electrode. Normally, when processing with pure water, if it is a non-conductor, the pure water portion does not conduct electricity, but this may partially conduct electricity by using a metal electrode. That is, a part of the electrode material dissolves in the pure water to form an electric path. As a result, a very small amount of the electrode material adheres to the surface of the work material. Next, the attached electrode material adheres to the blade surface as it is, 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 surface. The result of the adhesion is clear from the analysis result of the work surface.

  In each of the embodiments described above, the crystal 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 processing unit that performs electrolytic processing is basically the same as the configuration of the blade processing unit 202 (see FIG. 26) that performs electrical discharge machining, and a detailed description thereof will be omitted.

  Next, the mechanism of electrolytic processing is applied to a conventional electroformed blade (a blade using a metal binder by electroforming) (comparative example) and to a 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 blade)
When electroforming is performed on a conventional electroformed blade, a metal binder is used in the conventional electroformed blade. Therefore, there is no electric field concentration as shown in FIG. At the same time, electrolytic elution proceeds sparsely as a whole. Also, unlike a blade made of polycrystalline diamond, the electroformed blade has no grain boundaries and the like, and the binder simply retreats, and the next diamond abrasive comes out.

  To explain this mechanism in more detail, in the electroformed blade, the proportion of the metal binder portion occupies a larger portion than the diamond abrasive grains, and the binder portion gradually melts from a rich portion even when eluting. Further, since the diamond abrasive is a nonconductor (dielectric), no current flows near the diamond abrasive. Accordingly, the binder remains near 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 large, the metal component serving as the binder is rich, so that this portion elutes slowly. As a result, while the vicinity of the diamond abrasive grains rises to cover the edges of the diamond abrasive grains, the diamond abrasive grains elute in a bow-like manner with a large recess. As a result, sharp cutting edges are less likely to occur.

  Further, when such a metal material (binding material) is present on the surface, not only does electric field concentration occur on the surface, but on the contrary, the electrolyte 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 uniform. Further, not only is it difficult to form a sharp edge in the elution process, but also when the edge is formed, the base of the diamond abrasive grains is peeled off and the diamond abrasive grains themselves fall off immediately.

(When applied to polycrystalline diamond with sintered diamond abrasive)
Since the surface of polycrystalline diamond obtained by sintering diamond abrasive grains is rich in diamond, electric field concentration occurs in the sintering aid. Unlike polycrystalline diamond, such as a metal-plated whetstone, diamond abrasive grains are bonded to each other. I do.

  When electrolytically processing polycrystalline diamond by electric field elution, as shown in FIG. 31, the electric field concentrates particularly on a portion where the sintering aid is rich. For example, when Co (cobalt) or Ni (nickel) is used as a sintering aid, electric field concentration occurs in a portion of the diamond abrasive grains where the concentration of Co or Ni, which is a minute sintering aid, is high. Portions elute selectively. As a result, the permeation action and erosion action along the crystal grain boundaries become remarkable. Its permeation and erosion contribute to the formation of sharp cutting edges. That is, when the infiltration / erosion action occurs, a sharp cutting edge is formed by making the crystal grain boundaries stand out in a form like a deep crack. Elution occurs selectively from the grain boundary portion. Since the diamond abrasive grains are very close, they act deeply to erode between grain boundaries. This erosion greatly contributes to the formation of a new cutting edge.

  Sharp edges are constantly formed by erosion without premature dropping of diamond abrasive grains. The worn diamond abrasive grains on the surface of polycrystalline diamond fall off due to erosion of the crystal grain boundaries. After the diamond abrasive grains fall off, the adjacent portions are also diamond abrasive grains, so that the intervals between the diamond abrasive grains are still substantially uniform. The formation of such cutting edges at regular intervals is indispensable for performing ductile mode processing.

  Further, in the case of electrolytically machining polycrystalline diamond, as in the case of electric discharge machining, a mode of applying a voltage that alternately reverses the polarity between the polycrystalline diamond and the machining electrode (ie, a mode of applying an alternating electric field) Is preferred. Since diamond abrasive grains are dielectrics or non-conductors, elution does not progress easily even if 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, the sintering aid is electrolytically eluted from the surface of the polycrystalline diamond. When the polycrystalline diamond becomes the cathode while the elution of the polycrystalline diamond proceeds, conductive ions such as metal ions adhere to the surface of the polycrystalline diamond. By repeating adhesion and elution in this manner, it is possible to perform electrolytic processing even on the surface of polycrystalline diamond which is a dielectric.

  However, even in electrolytic processing, when the sintering aid of the diamond sintering aid has a small difference in the amount of elution between the rich grain boundary portion and the diamond abrasive grain portion that is not the grain boundary portion, the object of the present invention is 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, in the electrolytic processing, the sintering aid-rich grain boundary portion is largely eroded. It is desirable that the elution of the portion other than the grain boundary (diamond abrasive portion) does not progress much.

  Here, the electric field is particularly concentrated in the grain boundary portion where a relatively large amount of the sintering aid exists even in the polycrystalline diamond. Therefore, when the surface of the polycrystalline diamond becomes a cathode, the conductive ions adhere to the area where the conductive ions are attached, and the electric field concentrates on the grain boundary where the sintering aid exists, and the conductive ions close to the sintering aid. Adhere to. Attachment and elution of the conductive ions are repeated at the grain boundary portion where the sintering aid is relatively large, and the selective erosion of the grain boundary portion where the sintering agent is abundant is further promoted.

  In addition, various electrolytes can be used as the working fluid.Conventionally, the use of discharge oil allows pyrolytic carbon to adhere to the surface, and to be desorbed when it turns into an anode. The diamond surface had been machined. On the other hand, according to further studies by the present inventors, it has become clear 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 a processing liquid, since a small amount of ions are present in the processing liquid, the electric field concentration particularly near the sintering aid of the metal of polycrystalline diamond becomes more remarkable with the small amount of ions. , Greatly contributes to the local erosion effect. As a result, not the diamond abrasive grains but only the grain boundaries are significantly eroded and eluted. In particular, erosion can be suitably performed in combination with a mode in which an alternating electric field is applied.

  Further studies by the present inventors have found that even when ultrapure water is used as a working liquid, the sintering aid on the surface of polycrystalline diamond can be selectively eluted by electric field. Originally, when ultrapure water was used as a working fluid to be interposed between the polycrystalline diamond and the processing electrode, electric elution occurs on the surface of the polycrystalline diamond sintered body because the ultrapure water has no conductivity. It cannot be.

  However, by using a metal electrode as a processing electrode facing the surface of the polycrystalline diamond and combining it with the above-described mode of applying an alternating electric field, the electric field elution of the polycrystalline diamond became possible. Although the mechanism at this time is not clear, the use of an alternating electric field causes the metal of the electrode material to elute as metal ions once, adheres to the surface of the facing polycrystalline diamond, and further elutes the adhered portion. The mechanism by which it is processed is becoming clear.

  At this time, since the dissolved metal ions are very small and the opposite 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 that have melted out of the facing processing electrode form a selective electric path in the processing liquid (ultra pure water) by themselves, and adhere only to the vicinity of the sintering aid. . Next, the metal ions attached only to the vicinity of the sintering aid melt out together with the sintering aid, and more remarkably, the crystal grain boundary portion of polycrystalline diamond, that is, the portion where a large amount of the sintering aid exists, is selectively. Elute.

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

  Further, in order to elute such an electrode material to selectively adhere to and elute the sintering aid portion on the surface of the polycrystalline diamond, it is desirable to combine the above-described mode of applying the alternating electric field. When using an electrolytic solution that is difficult to conduct electricity as a working fluid and repeatedly attaching and detaching while causing an electric field concentration on polycrystalline diamond, ideal erosion occurs, and as a result, an ideal cutting edge is formed can do.

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

(Modification 1)
In each of the embodiments described above, the case where the electric machining (electric discharge machining or electrolytic machining) is performed on the blade 26 made of the polycrystalline diamond 26a has been described. However, the present invention is not limited to this, and a tool having a similar configuration (for example, , Whetstone, etc.), it is also possible to perform electric machining (discharge machining or electrolytic machining) by a machining apparatus having a configuration similar to that of the blade machining apparatus, and obtain the same operation and effects as those of 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. It is applicable even if it is.

  DESCRIPTION OF SYMBOLS 10 ... Dicing apparatus, 20 ... Processing part, 26 ... Blade, 26a ... Polycrystalline diamond, 28 ... Spindle, 30 ... Work table, 36 ... Circular part, 38 ... Mounting hole, 40 ... Cutting blade part, 42 ... Diamond abrasive 44, spindle body, 46, spindle shaft, 48, hub flange, 80, diamond sintered body, 82, diamond abrasive, 84, cutting edge (micro cutting edge), 86, sintering aid, 200, blade processing Apparatus, 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 (1)

A work processing apparatus including a blade processing unit that regenerates a cutting edge on a blade surface by removing a crystal grain boundary portion of polycrystalline diamond constituting a blade by electric discharge machining using water.