JP2002036017A - Drill having single crystal diamond at its tip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology of machining a drill top considering machining property and abrasion resistance of the edge lip of quadrangular pyramid and to provide a reaming effect and a dimension measuring effect, in a single crystal diamond drill. SOLUTION: The tip of the single crystal diamond (hexahedron diamond 1) has the quadrangular pyramid, and the center line of the quadrangular pyramid matches to one crystal axis of the single crystal diamond and a drill axis. When the tip of the diamond is projected on an axis perpendicular plane of the drill axis, the projected image of the edge of the quadrangular pyramid is angled by 45 deg.±5 deg. with respect to two remaining crystal axes, and further a pair of sharpnesses of the quadrangular pyramid are in a range of 90 deg.±10 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill having a single crystal diamond at its tip, and more particularly to a drill suitable for drilling holes in hard brittle materials, for example, quartz glass, silicon, machinable ceramics or IC substrates. . Furthermore,
Useful for drills of normal size as well as for small diameter drills or finer pores, so-called
It relates to the field of microdrill technology.

[0002]

2. Description of the Related Art Via holes are frequently used for connection between layers in a multilayer substrate on which an IC package is mounted. It is desired that the diameter of the via hole be as small as the manufacturing technology allows.

[0003] Conventionally, via holes and other holes are drilled.
A microdrill made of a cemented carbide having a helical blade groove, or a microdrill provided with a wear-resistant layer by coating a number of fine diamonds on the surface of the blade portion of the cemented carbide of the microdrill by a plating method, Alternatively, a micro-drill having a cemented carbide shaft having a helical groove and a polycrystalline diamond brazed to the tip is used.

[0004] Since these micro drills have a spirally wound blade groove (twist groove), when the diameter is small, not only the manufacturing becomes difficult, but also the cross sectional area of the drill is reduced by the provision of the twist groove. , The strength has been reduced and the use limit has been reached.

The twist groove is provided from the tip cutting edge to just before the shank in order to discharge chips generated at the tip of the drill. Such a twist groove is conventionally considered to be indispensable, and for example, it is almost provided except for a drill having a special chip discharge structure such as a gun drill or a core leaving drill.

Further, a chisel edge is formed at the tip of the drill, and the chisel edge has little or no distance from the center. Therefore, the peripheral speed at this point is little or zero. On the one hand, the axial advance speed of the drill is equal everywhere, regardless of the distance from the center of rotation, so that the rake angle is theoretically negative and little or no cutting action occurs at the chisel edge.

Further, conventionally, the chisel edge has two ridges which gradually become higher toward the center of the drill (chisel point). However, since the angle formed by these two ridges is not sharp, the tip of the drill is formed. (Ie the chisel point) bites into the workpiece, causing a slight distortion of the surface of the workpiece, local variations in the material of the workpiece,
The center may slightly deviate from the center due to unpredictable conditions such as shaft deviation of the drill. Such a slight shift of the biting position greatly affects the final position of the drilled hole.

Further, even if the drill bites into the workpiece at the intended position, a phenomenon may occur in which the direction of travel of the tip of the drill changes during the drilling and the hole is bent.

For this reason, in a drill having a low strength, such as an ultrafine microdrill, the drill is broken due to the application of a lateral force, or a hole (a front opening circle or a back opening circle) drilled even if not broken. A phenomenon occurs that the center deviates from the intended position.

[0010] In addition, when a polycrystalline diamond drill is used for drilling a hard brittle material such as quartz glass, a silicon plate, or machinable ceramics, the life of the drill is short, or the biting at an intended position is poor. There is also a problem of axis breakage which causes.

In order to avoid the adverse effects of such a non-sharp drill tip and to avoid a reduction in strength due to a twist groove, a drill having a pyramid tip and no twist groove has been considered.

Under these circumstances, the idea of forming the drill tip (cutting edge portion and guide portion) with single crystal diamond in order to increase the strength of the tip has been proposed in Japanese Utility Model Application Laid-Open No. H05-163,873.
No. 9814 (Japanese Utility Model Application No. 3-83585) and its CD-ROM specification. Here, 4
It is described that a rectangular prism guide portion and a leading end connected to the prism portion are formed of a single crystal diamond with a square angle of 60 ° to 90 °.

As is widely known, diamond is the hardest substance in the world, and has a very wide application such as jewelry and industrial use. In recent years, relatively inexpensive industrial diamonds have been supplied due to the development of diamond synthesis technology, but they are still expensive.

In the drill disclosed in the above publication, since the portion from the tip to the guide portion is made of single crystal diamond, a large single crystal diamond is required, which is very expensive and impractical. Furthermore, this publication does not consider or disclose the direction of the crystal axis when processing a single crystal diamond and the crystal plane when attaching to a drill shaft.

[0015]

The shape (outside shape) and size of diamond supplied irrespective of nature or synthesis are varied by accident during synthesis. For this reason, when processing the diamond, individual measures must be taken for each of the supplied diamonds.

That is, diamond is difficult to process because of its high hardness. Usually, diamond powder is applied to a rotating cast iron disk and pressed against the disk. Since diamond has a crystal structure, its physical and chemical properties show anisotropy depending on the crystal direction, and its workability is no exception.

Since there is no material harder than diamond, there is no material that can be selected as a material to be processed, which is more than diamond. Therefore, it is practically or practically possible to freely process a diamond single crystal in any direction. Is impossible.

FIG. 1 shows a crystal plane of a diamond crystal. Diamond has a cubic crystal structure, and three types of crystal planes appear in the crystal as shown in this figure.

In FIG. 1, (a) shows a {100} plane and a crystal composed of only this plane. A {100} plane appears for each of the crystal axes x, y, and z (the {100} plane, the {101} plane, and the {001} plane are equivalent to each other), and the flesh side (inside) and the space side of the crystal. There are apparently a total of six faces, depending on whether the face that separates is on the front or back, respectively. The case composed of only these six planes is a hexahedral crystal shown in FIG.

(B) shows a {110} plane, and a crystal composed only of this plane. Similar to (a), there are a total of twelve faces in appearance. The case composed of only these 12 planes is a dodecahedral crystal shown in FIG. Further, (c) shows a {111} plane, and a crystal composed only of this plane. Similarly, there are a total of eight faces in appearance. An octahedral crystal shown in FIG. 1 is composed of only these eight planes.

These three planes usually appear in a composite. FIG. 2 is a diagram showing an example of a diamond single crystal in which all three types of crystal planes appear. However, it is rare that the shape becomes a nearly spherical and uniform shape as shown in FIG.

As described above, the workability greatly differs depending on the crystal plane. FIG. 3 is a graph showing the relationship between the crystal orientation and wear (workability), and showing that the workability differs depending on the orientation. The experiment was carried out by placing a diamond set at a predetermined polishing angle on a cast iron plate held horizontally and polishing the same for a certain load and for a certain time. The polishing angle in the direction parallel to the crystal axis was set to 0 degree, and only the octahedral plane {111} plane was selected and tested in an arbitrary direction.

As can be seen from the graph of FIG. 3, the dodecahedral surface {110} has the highest workability, and the hexahedral surface {10}
The 0 ° plane follows. On the other hand, the octahedral surface {111} was hardly polished with almost no wear.

FIG. 4 is a Grozinsky stereographic projection showing the polishing difficulty when the single crystal diamond is tilted from a typical crystal plane to an adjacent crystal plane. Arrows indicate polishing directions and easy polishing, and dotted lines indicate difficult polishing.

When a quadrangular pyramid is obtained by polishing from a cubic diamond shown in FIG. When the angle reaches 45 degrees, 12
A quadrangular pyramid consisting of the face plane {110} is obtained.

FIG. 4 shows that the polishing orientation inclined from the hexahedral surface {100} to the dodecahedral surface {110} indicates that polishing is difficult. However, as can be seen from FIG.
Since the wear tendency is different depending on the polishing direction on each crystal plane, the polishing direction poses a problem. Therefore, when the angle is inclined near the dodecahedral surface {110}, the polishing is facilitated by selecting the polishing direction.

The ridges of the quadrangular pyramid obtained at this time constitute the wear-resistant cutting edges shown in FIG.

The present invention provides a technique for machining a drill top in consideration of such workability and the wear resistance of a ridgeline cutting edge of a pyramid, and further obtains a reaming effect and an effect of dimensioning. It is an issue.

[0029]

The above object is achieved by the following means. That is, a "means for solving the first invention" A means for solving the first invention is a drill having a single crystal diamond at a tip thereof, and the tip of the single crystal diamond has a quadrangular pyramid surface. And the center line of the pyramid coincides with one crystal axis and the drill axis of the single crystal diamond.
When projected onto the plane perpendicular to the axis of the drill axis, the projected image of the ridge of the pyramid forms an angle of 45 ° ± 5 ° with the remaining two crystal axes.

[Second Solution of the Second Invention] A second solution of the invention is directed to a drill having the single crystal diamond according to the first invention at the tip thereof, wherein the diagonal angle of the quadrangular pyramid is 90 degrees. The range is ± 10 degrees.

[Third Solution of the Invention] A third solution of the present invention is to provide a drill having the single crystal diamond of the first or second invention at its tip, wherein the single crystal diamond is , A hexahedral diamond composed of hexahedral planes {100}. These forms, including those grown artificially, can be obtained from a large crystal by laser cutting or the like.

[Fourth Solution to the Invention] In a drill having the single crystal diamond according to the first to third inventions at the tip thereof, the single crystal diamond is brazed to a drill axis by a {100} plane. It is attached.

"Fifth Solution of the Invention" A fifth solution of the invention is directed to a drill having a single crystal diamond according to the first to fourth inventions at the tip thereof, wherein the center axis of the drill is And a plane forming an angle in the range of 65 degrees to 85 degrees with respect to the plane including the ridge line, the clearance angle dropped is formed.

"Sixth Solution of the Invention" A sixth solution of the invention is directed to a drill having the single crystal diamond of the first to fifth inventions at the tip thereof, wherein the single crystal diamond is In the bottom corner of the pyramid of
A negative rake angle formed by a plane parallel to the drill axis and at an angle in the range of 65 to 85 degrees with respect to the plane including the ridgeline and the central axis of the drill is formed. .

[Seventh Solution of the Invention] A seventh solution of the invention is a drill having first to sixth single crystal diamonds at the tip thereof, wherein the drill is a small diameter drill and It is a drill including a micro drill.

Further, in this specification, in a drill having first to seventh single crystal diamonds at its tip, the material of the drill shaft is made of cemented carbide, and the material of the drill shaft is made of steel. That the cylindrical surface of the drill shaft to have a wear-resistant layer of fine diamond, and
It is disclosed that brazing of a single crystal diamond to a drill shaft is performed in an inert gas.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIGS. 1 and 2 show examples of the shape of a diamond to be produced or synthesized.
It has been explained that it is rare that such a uniform shape is obtained. The single crystal diamond synthesized by the diamond synthesis method is a truncated hexahedron composed of a plane {100} and a plane {111} (a plane {111} appears at a corner) as shown in FIG. This large crystal has a crystal plane orientation, is cut into a predetermined size by a laser, and becomes a hexahedral (quadrangular prism) diamond having a plane {100} (see FIG. 8).

In FIG. 5, a part of the drill shaft 2 to which the truncated hexahedral diamond 1 is attached is shown by a dotted line. In addition, for easy understanding, FIG.
Although the balanced one of the face diamonds 1 is shown, the one actually used may be somewhat distorted (the size of the upper and lower {100} planes is different, for example). However, even in this case, the direction of each crystal plane is constant due to the nature of the crystal.

FIG. 6 shows the truncated hexahedral diamond 1
3A is a top view as viewed from the z-axis direction, FIG. 3B is a side view as viewed from the y-axis direction, and FIG. Side view, viewed from
(D) is a side view seen from the 45 degree direction in (a).

In the embodiment of the present invention, a truncated hexahedral diamond at the tip of a drill or a hexahedral (quadrangular prism) diamond having a face {100} is brazed to the drill shaft 2 by a {100} face below the diamond. The diamond is polished by being indexed by 90 degrees around the z-axis (drill center axis) by the polished surface p1 shown in (b). In this example, the inclination between the polished surface p1 and the z-axis is 35 degrees 16 minutes.

The quadrangular pyramid thus formed becomes the tip of the drill having the same axis as the drill axis, and its four ridges are 3
It does not have a direction parallel to two crystal axes and shows a wear-resistant orientation.

In this example, the facing angle is 70 degrees 32 minutes (inclination with the z-axis with respect to the polished surface p1 is twice 35 degrees 16 minutes).
Therefore, as shown in FIG. 6D, the diagonal angle of the formed quadrangular pyramid is equal to the diagonal angle of the octahedral crystal.
It becomes degree. Note that, when viewed in FIG. 6A, the ridge lines appear in a direction of 45 degrees with respect to the x-axis and the y-axis shown by the dotted lines.

The angle between the drill and the ridge is not limited to 90 degrees, but can be selected within a range of 90 degrees ± 10 degrees. The reason for choosing the conical angle in this range is that the conical angle of the drill is 1
If the angle exceeds 00 degrees, the biting of the drill becomes worse, and the accuracy of the center position of the drilled hole deteriorates.
If the temperature is lower than that, the leading edge portion is easily chipped and the life is shortened. That is, the range is determined in consideration of the balance between the life and the accuracy.

FIG. 7 shows the diamond 1 formed on the quadrangular pyramid surface thus created and the drill shaft 2 to which the diamond 1 is fixed.

In other words, the four-sided pyramid is a four-sided pyramid.
The center line of the pyramid coincides with one crystal axis and the drill axis of the single crystal diamond, and when projected on a plane perpendicular to the axis of the drill axis, the projected image of the ridge line of the quadrangular pyramid remains.
Although it is 45 degrees with respect to one crystal axis, it can be in a range of ± 5 degrees from this angle in some cases.

The drill shaft 2 has a normal shank 15 (see FIG. 15) for gripping a drill, and in the embodiment of the present invention, it can be used as a drill in this state. However, the ridges that determine the diameter of the drilled hole are not always equidistant from the axis and form a corner, so that the inner surface of the drilled hole is roughened. Therefore, in order to adjust the diameter of the hole to be drilled, the surrounding portion 5 shown in FIG.
Corner 8 (corner of the cone bottom) is dropped by two planes parallel to the drill axis.

FIG. 8 is a plan view seen from the drill axis direction. As shown in FIG. 8, four base pyramids of the single crystal diamond have four base corners parallel to the drill axis.
65 to 85 degrees with respect to the plane including the center axis and ridge of the drill
The clearance angle dropped by the surface (polishing surface p2) having an angle of up to degrees, and the surface (polishing surface p2) forming an angle of 65 to 85 degrees with respect to the surface including the center axis and the ridge line of the drill.
The negative rake angle dropped by 3) is formed. FIG. 9 shows the vicinity of the tip of the drill in which the clearance angle and the rake angle are formed. The new ridge 20 formed by the two surfaces is parallel to the axis and determines the diameter of the processed hole and improves the surface roughness of the hole.

FIGS. 10, 11, 12, and 13 show another example, that is, the process of manufacturing a drill according to the present invention from hexahedral diamond (ie, a single crystal diamond that is not truncated hexahedron). FIG. 5, respectively.
This corresponds to FIGS. 6, 7, and 9. FIG. This process is almost the same as the case of the truncated hexahedral diamond described above, and will not be described. However, at the stage when the tetragonal pyramidal surface is formed, a part of the ridge of the hexahedral diamond existing from the beginning is left as shown as a ridge 21 in FIG. This ridge 21 is parallel to the drill axis and performs a reaming function as it is. However, in order to obtain the size of the hole diameter, the ridge 21 is parallel to the drill axis as shown in FIG. The edge 20 is dropped on two surfaces (Fig. 1
3) is formed.

FIG. 14 is an overall view of a drill having a tip of a completed single crystal diamond according to the embodiment of the present invention. Except for the tip, the configuration can be the same size and shape as a normal drill, for example, a micro drill. The drill shaft 2 uses carbide as its material, and can prevent the drill shaft 2 from being thinned due to chips. On the other hand, carbide is brittle and easily breaks, so the drill shaft is made of high toughness steel, and in order to prevent thinning due to cutting chips that are likely to occur in this case, a fine diamond is attached to the surface of the drill shaft to prevent wear. Can be provided. This wear-resistant layer can be provided even when the drill shaft is made of a super hard material.

After the hexahedral diamond 1 of the material is fixed (brazed) to the drill shaft 2 in advance, it can be processed into a quadrangular pyramid as described above.
It is also possible to attach to another shaft and process it into a quadrangular pyramid, then remove it and fix it to the drill shaft. In the former case, the strict alignment for ensuring the alignment between the tip of the drill and the shank as in the latter case is not required, so that the productivity is improved. It is better to perform brazing in an inert gas.

Further, the drill according to the embodiment of the present invention is sharply pointed, so that it does not deviate from the center when it bites into the workpiece, thereby making it possible to drill holes with high positional accuracy.

[0052]

According to the present invention, the ridge line of the single crystal diamond pyramid at the tip of the drill imparts wear resistance crystallographically,
This has the effect of extending the life. Furthermore, since the drilling radius and the reaming effect can be obtained by dropping the corner of the cone bottom, the drill according to the present invention has high diameter accuracy and good inner surface roughness. Holes can be drilled.

Since the drill of the present invention has a quadrangular pyramid at the tip, it has good bite and can form a hole with high positional accuracy. Further, the drill shaft has a fine diamond layer having high wear resistance. This has the effect that the problem that the drill shaft becomes thinner is less likely to occur. One of the present inventions has an effect that the toughness is high and the breakage is small because the drill shaft is made of steel.

In the present invention, the brazing between the single crystal diamond and the drill shaft is performed in an inert gas. For this reason,
This has the effect that the brazing strength does not decrease under the influence of air.

In the present invention, an edge (ridge) parallel to the reaming drill axis is formed at the corner of the bottom of the quadrangular pyramid, so that the diameter of the hole is adjusted and the inner surface of the drilled hole is adjusted. It can be processed well.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a crystal plane of a diamond crystal and a crystal outline formed by the plane.

FIG. 2 is a bird's-eye view showing an example of a diamond single crystal in which all three crystal planes appear.

FIG. 3 is a graph showing the relationship between crystal orientation and wear (workability), and showing that workability differs depending on the orientation.

FIG. 4 shows Grozinsk showing polishing difficulty when tilted from a typical crystal plane of a single crystal diamond to an adjacent crystal plane.
It is a stereo projection view of y.

FIG. 5 is a bird's-eye view showing a truncated hexahedral diamond and a part of a drill shaft to which the diamond is attached.

FIG. 6 shows a top view of the truncated hexahedral diamond 1 and a side view from three directions, where (a) is a top view as viewed from the z-axis direction and (b) is a side view as viewed from the y-axis direction. Figure,
(C) is a side view seen from the x-axis direction, (d) is (a)
5 is a side view as viewed from a 45-degree direction.

FIG. 7 is a bird's-eye view showing a truncated hexahedral diamond in which a tetragonal pyramid is created and a drill shaft to which the diamond is fixed.

FIG. 8 is a plan view seen from a drill axis direction.

FIG. 9 is a view showing the vicinity of a drill tip where a clearance angle and a rake angle are formed.

FIG. 10 is a bird's-eye view showing a hexahedral diamond (a non-truncated hexahedral diamond single crystal) and a part of a drill shaft to which it is attached.

11A and 11B are a top view and a side view of a hexahedral diamond viewed from three directions, respectively. FIG. 11A is a top view viewed from a z-axis direction, and FIG. 11B is a side view viewed from a y-axis direction. ,
(C) is a side view seen from the x-axis direction, and (d) is a side view seen from the 45 degree direction in (a).

FIG. 12 is a bird's-eye view showing a hexahedral diamond in which a tetragonal pyramid surface is created and a drill shaft to which the diamond is fixed.

FIG. 13 is a view showing the vicinity of a drill tip where a clearance angle and a rake angle are formed.

FIG. 14 is an overall view of a drill having a tip of a completed single crystal diamond according to an embodiment of the present invention.

[Explanation of symbols]

 1 (truncated) hexahedral diamond 2 drill axis 20, 21 ridge 15 shank p1, p2, p3 Polished surface

Claims (7)

[Claims] 1. A drill having a single crystal diamond at its tip, wherein the tip of the single crystal diamond is
It has a tetragonal pyramid surface, the centerline of which is coincident with one crystal axis and the drill axis of the single crystal diamond, and further projected onto the plane perpendicular to the axis of the drill axis. Characterized in that the projected image of the ridge line is at an angle of 45 ° ± 5 ° with respect to the remaining two crystal axes, the drill having a single crystal diamond at its tip. 2. The drill according to claim 1, wherein a single crystal diamond is provided at a tip of the drill, wherein a diagonal angle of the quadrangular pyramid is in a range of 90 degrees ± 10 degrees. A drill at the tip. 3. A drill having a single-crystal diamond at its tip according to claim 1 or 2, wherein the single-crystal diamond is a hexahedral prism having a hexahedral surface {100}. A drill having a single crystal diamond at its tip, which is polished from diamond or truncated hexahedral diamond. 4. The drill according to claim 1, wherein the single crystal diamond is brazed to a drill axis by a {100} plane. A drill having a single-crystal diamond at its tip. 5. The drill according to claim 1, wherein a single crystal diamond is provided at a tip of the drill. A single crystal, characterized in that a parallel plane has a clearance angle dropped by a plane forming an angle in a range of 65 to 85 degrees with respect to a plane including a central axis of the drill and a ridge line. Drill with diamond at its tip. 6. The drill according to claim 1, wherein a single crystal diamond is provided at a tip of the drill. A simple rake angle formed by a plane parallel to the plane including the center axis of the drill and the ridge line and having an angle in the range of 65 degrees to 85 degrees is formed. Drill with crystal diamond at its tip. 7. A drill according to any one of claims 1 to 6, having a single crystal diamond at its tip, wherein the drill is a drill including a small diameter drill and a micro drill. With a single crystal diamond at its tip.