JP2017074789A - Scribing wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scribing wheel for scribing a brittle material substrate so that it can increase the end surface strength when fragmented.SOLUTION: A rotation axis is located at the center of a disc-shaped scribing wheel substrate, and a tip of a V-shaped section is formed at a circumferential portion and with a diamond film at the tip. At this time, a diamond film of a single layer of a film thickness of 10 to 30 μm is formed by a chemical vapor deposition method. Diamond particle diameters are made to have an average particle diameter of 2 to 10 μm. After this, a ridge part is polished to correct the tip sharp. As a result, the roughness of the ridge part can be made fine. When this scribing wheel is used to scribe the brittle material substrate, the end face precision of the segmented substrate can be increased to improve the end face strength.SELECTED DRAWING: Figure 2B

Description

  The present invention relates to a scribing wheel for scribing by pressing and rolling on a brittle material substrate.

  Conventional scribing wheels are based on a disc made of cemented carbide or polycrystalline sintered diamond (hereinafter referred to as PCD). PCD is obtained by sintering diamond particles together with cobalt or the like. The scribing wheel is formed by cutting the circumferential edges obliquely from both sides of a disk as a base material to form a V-shaped cutting edge on the circumferential surface. The scribing wheel formed in this way is rotatably attached to a scribing head of a scribing device, pressed against the brittle material substrate with a predetermined load, and moved along the surface of the brittle material substrate to roll it. You can scribe while.

  Patent Document 1 discloses a glass cutting blade in which a V-shaped blade edge surface is coated with diamond in order to increase the life of the glass cutting blade for cutting a glass substrate. This blade for cutting a glass is shaped by coating a diamond film on the surface of a cutting edge formed of a ceramic that is compatible with diamond and then polishing the diamond film. It has been shown that by using such a glass cutting blade, the high-hardness glass can be cut such that the blade has a long life and the cut surface is smooth.

  Patent Document 2 discloses a diamond-coated cutting blade in which a base material such as cemented carbide is coated with a diamond layer in order to prevent slippage or deterioration of cutting quality when cutting an optical fiber, a glass substrate, or the like. ing. This document is characterized in that the surface of the diamond layer is not smoothed after coating.

  On the other hand, when the diamond film is polished, the film thickness becomes thinner by the polishing than before the polishing. Therefore, it is necessary to make the film thickness at the time of film formation thicker than when the smoothing treatment is not performed. Conventionally, in order to increase the film thickness, the diamond film formation time has been lengthened and the diamond films have been stacked in multiple layers. Patent Document 3 discloses a diamond-coated tool having a diamond coating having a multi-layer structure of microcrystals formed by repeating the nuclear deposition process and the crystal growth process so that the crystal grain size of the surface and the cross section is 2 μm or less. Is described. By making the diamond film multi-layered as described above, it is possible to form a relatively thick diamond film while maintaining a small crystal grain size of diamond and reducing irregularities on the surface of the film.

Japanese Patent Laid-Open No. 04-224128 JP 2011-126754 A Japanese Patent No. 3477162 Japanese Patent No. 3074143

  It has been found that when the brittle material substrate is actually scribed using the glass cutting blade described in Patent Document 1, chipping of the blade edge, peeling of the diamond film, and the like are likely to occur. Even in the diamond-coated cutting blade described in Patent Document 2, since the surface is not smoothed, when the brittle material substrate is scribed, the end face accuracy of the substrate is deteriorated as compared with the case where the polishing is not performed. However, the end face strength is inferior.

  In addition, since the diamond coating described in Patent Document 3 has a multilayer structure in which a number of thin coatings are stacked, the properties in the layers of the coating and between the layers are not uniform. For this reason, even if the diamond film described in Patent Document 3 is formed on the scribing wheel and the surface of the film is to be polished, it is difficult to perform uniform polishing. Furthermore, in the scribing wheel after polishing, the particle size of the coating that appears on the surface of the cutting edge by polishing is not uniform within the layer and between the layers, so that a portion that is easily worn and a portion that is difficult to wear are generated on the wheel cutting edge, and a brittle material When the substrate is scribed, there is a problem that a part of the blade edge is excessively worn and the life of the scribing wheel is shortened. Further, the deformation of the scribing wheel due to wear tends to cause the diamond film to peel off, and further shortens the life of the scribing wheel.

  Further, Patent Document 4 describes a scribing wheel in which a large number of grooves are formed at a predetermined interval on the circumferential surface of the scribing wheel, and a high penetration type is formed with protrusions therebetween. When a multi-layer diamond coating such as the diamond coating described in Patent Document 3 is applied to such a scribing wheel, the groove processing is usually performed from above the diamond coating. If the depth of the groove is deeper than the thickness of one layer of the film, parts that are likely to wear and parts that are difficult to wear will appear on the side of the groove, and it will be difficult to maintain the shape of the groove due to groove wear and chipping. There is a problem of becoming.

  The present invention has been made in view of such problems, and in a scribing wheel coated with a diamond film, improves the end face strength and end face accuracy of the brittle material substrate when the brittle material substrate is scribed and broken. An object of the present invention is to provide a scribing wheel that can be used and that the cutting edge is less likely to wear and that has a long life.

In order to solve this problem, the scribing wheel of the present invention includes a scribing wheel base material having a ridgeline formed along a circumferential portion, and having a cutting edge composed of the ridgeline and inclined surfaces on both sides of the ridgeline, and the scribing wheel. comprising a diamond film formed on the edge surface of the substrate, said strip-shaped region and the polishing region including the ridge line of the diamond film, the average particle size of the diamond particles in the abrasive region be 2.5μm or less , characterized in that the thickness of the vicinity of the ridge line and 5 to 25 [mu] m.

Here, the arithmetic average roughness Ra of the ridge line may be 0.015 μm or less.

  Here, a groove in which a ridge line portion of the polishing region is notched at a predetermined interval may be provided, and a portion between the grooves may be formed as a protrusion.

According to the present invention having such a feature, a diamond film having a single layer structure is formed by attaching diamond fine particles to a scribing wheel base material and growing a crystal. Therefore, the diamond film can be made uniform, and the accuracy of subsequent polishing can be easily improved. In addition, since the film is uniform, the surface of the blade edge is uniformly worn when scribing a brittle material substrate having high hardness, so that the wear property is improved. And scribing wheel can be reduced surface roughness of the blade edge, to improve the end face accuracy of the brittle material substrate, the effect is obtained that the end faces strength can be improved. In addition, when scribing a brittle material substrate having high hardness, it is possible to obtain an effect that it is difficult to cause chipping or peeling due to fine unevenness in the ridge line portion.

FIG. 1 is a side view of a front view of a scribing wheel according to a first embodiment of the present invention. FIG. 2A is an enlarged cross-sectional view of a ridge line portion before polishing of the blade edge according to the first embodiment. FIG. 2B is an enlarged cross-sectional view of a ridge line portion after polishing according to the first embodiment. FIG. 3A is a front view of a scribing wheel according to the second embodiment of the present invention. FIG. 3B is an enlarged cross-sectional view of a ridge line portion after polishing according to the second embodiment. FIG. 3C is an enlarged view of the circular portion shown in FIG. 3A. FIG. 4A is a diagram showing the edge angle and arithmetic mean roughness of the scribing wheel according to Example 1 before and after polishing. FIG. 4B is a diagram illustrating the edge angle and arithmetic average roughness of the scribing wheel according to Example 2 before and after polishing. FIG. 4C is a diagram showing the edge angle and arithmetic mean roughness of the scribing wheel according to Example 3 before and after polishing.

  FIG. 1 (a) is a front view of a scribing wheel according to the first embodiment of the present invention, and FIG. 1 (b) is a side view thereof. When manufacturing a scribing wheel, for example, a through-hole 12 serving as an axial hole is first formed in the center of a disc 11 serving as a base material of a cemented carbide or ceramic scribing wheel, as shown in FIG. To do. Next, a shaft such as a motor (not shown) is connected to the through hole 12 to rotate the central axis of the through hole 12 as the rotation shaft 12a, and the entire circumference of the disk 11 is connected to the rotation shaft 12a from both sides of the disk. On the other hand, it is polished obliquely and formed into a vertical V-shaped section consisting of a slope and a ridgeline as shown in FIG. The V-shaped slope formed in this way is defined as a polishing surface 13.

  Next, formation of the diamond thin film formed on the polished surface 13 will be described. First, the V-shaped polished surface 13 is roughened in advance so that the diamond film can be easily attached. Next, the scribing wheel substrate is maintained at a predetermined temperature, pressure, atmosphere, etc., and diamond nuclei are generated on the surface of the polished surface. This nucleus is made of single crystal diamond or agglomerated single crystal diamond, and has an outer diameter of, for example, several nm to several tens of nm. Then, diamond nuclei are grown by chemical vapor deposition (CVD) to form a diamond thin film. In this growth, the average particle diameter of diamond is 2 to 10 μm, preferably 4 to 8 μm, more preferably about 5 μm, and the film thickness is, for example, 10 to 30 μm. If the particle size of diamond exceeds 10 μm, it is difficult to sufficiently reduce the surface roughness even if polishing is performed. Further, when the grain diameter of the grain diamond exceeds 10 μm, the wear resistance is lowered. Further, when the film thickness of the diamond film exceeds 30 μm, it is easy to peel off during film formation, and when it is less than 10 μm, the film thickness after polishing becomes too thin. In this way, a single-layer diamond film 14 can be formed on the polishing surface 13 as shown in an enlarged cross-sectional view near the edge line of the blade edge in FIG. 2A. Since the diamond film 14 is a single layer, there is no difference in the grain size of diamond between layers, and the diamond film can be made uniform, so that the accuracy of subsequent polishing can be improved. Also in the layer, the properties of the diamond film are different between the vicinity of the diamond nucleus and the surface of the diamond film. However, since the thickness of the diamond film 14 is sufficiently thick as 10 to 30 μm, even after polishing. The portion near the nucleus of the diamond with different properties does not appear on the cutting edge surface of the scribing wheel. Therefore, even when scribing a brittle material substrate with high hardness, there are no parts that cause peeling or easy to wear on the blade surface, and the wear resistance and life of the scribing wheel are improved. Can do.

  Here, when the diamond film 14 is formed on the polished surface 13, diamond crystal irregularities are formed on the film surface, and the average particle diameter of the diamond particles is measured by detecting the irregularities with a scanning electron microscope (SEM). be able to. Since the SEM has a resolution of about 0.5 to 4 nm, several diameters of the irregularities formed on the diamond film are measured, the diameter of the crystal appearing on the surface (the length of the major axis) is measured, and the average grain size is calculated. . Thus, when measuring by SEM, an average particle diameter can be measured only by observation of the surface. In this measurement method, a material showing a predetermined numerical range can be considered to have a surface roughness roughly similar to that when polished.

  Thereafter, at least the tip of the diamond film is polished so that the tip is sharp. FIG. 2B is a partially enlarged sectional view showing the state after the polishing. Here, the polishing may be performed in two stages of rough polishing and final polishing, and may have an obtuse angle of, for example, about 5 ° with respect to the original diamond film 14. By performing the two-stage polishing of rough polishing and final polishing, the surface roughness of the polished surface and ridge line after polishing can be sufficiently reduced while shortening the processing time. Then, the surface including the circle composed of the ridge line after polishing is set to be perpendicular to the rotation axis 12a. The region to be polished here may be only a belt-like portion including the ridge line in the center. The region of the width w of polishing in FIG. 2B shows this tip portion, that is, the polishing region of the diamond film on both sides of the ridgeline. For example, the value of the width w is 10 to 30 μm. When the diamond film having the above-described thickness is polished in this way, the thickness d of the thinnest part near the ridgeline of the diamond film 14 having a single layer structure is, for example, 5 μm to 25 μm. If the thickness d is small, the diamond film may be peeled off during scribing, and if it is too large, there is a problem that it is easily cracked by internal stress. Furthermore, since the thickness of the diamond film 14 is sufficiently thick at 5 to 25 μm even after polishing, a portion near the diamond nucleus having different properties does not appear on the surface of the cutting edge of the scribing wheel. Therefore, it is possible to make the particle size and properties of the blade edge surface uniform, and in particular, there are no places that cause peeling or easy to wear, and the wear resistance and life of the scribing wheel can be improved. it can.

  The scribing wheel is polished by an abrasive such as a grindstone. One inclined surface of the diamond film formed on the cutting edge of the scribing wheel is subjected to rough polishing or finish polishing with a grindstone. By processing with a grindstone, it is possible to equalize the roughness of both inclined surfaces, to polish the inclined surface at the same angle over the entire circumference of the scribing wheel, or to make the ridge line of the scribing wheel straight in a side view It becomes easy. When the polishing of one surface is finished, the other surface is similarly polished. In this polishing step, polishing is performed until the arithmetic average roughness Ra of the inclined surface after polishing becomes 0.03 μm or less, preferably 0.015 μm or less. Further, it is preferable to polish until the arithmetic average roughness Ra of the ridge line is 0.03 μm or less, preferably 0.015 μm or less.

  By polishing in this way, the average roughness of the diamond film in contact with the brittle material substrate is smaller than that of a conventional scribing wheel made of sintered diamond, so that the roughness of the edge portion and the edge line can be made fine. Therefore, by scribing and dividing a brittle material substrate, for example, a ceramic substrate, using this scribing wheel, the accuracy of the end face of the cut surface of the brittle material substrate is improved, and the end face strength can be improved accordingly. . Furthermore, the effect of making it difficult for the diamond film to peel off is obtained by reducing the roughness of the cutting edge and the ridgeline. Therefore, the scribing wheel of the present invention is suitable for scribing a high hardness brittle material substrate such as a ceramic substrate.

  As described above, when all the surfaces of the diamond film 14 are polished after the diamond film 14 is formed, the unevenness of the diamond particles cannot be directly detected by SEM after the polishing. Can not do it. Therefore, a method for measuring the particle size of the polished portion will be described below in order to confirm whether the diamond particles of the diamond film 14 have a desired particle size even after the diamond film is polished.

  According to the electron backscatter diffraction method (EBSD method), if the sample is irradiated with an electron beam from an angle inclined by 60 to 70 °, a diffracted electron beam can be obtained in a region of 50 nm or less from the surface of the sample. By analyzing the backscatter diffraction, information on the orientation analysis of the crystalline material can be obtained. Using this information, the crystal grain size of polycrystalline diamond can be observed even after the diamond film is polished.

  In order to confirm the effectiveness of the EBSD method, an EBSD is used by using as a sample a scribing wheel having a substrate ridge line angle of 100 ° and a diamond film ridge line angle of 120 °, which has an average particle diameter of 2 to 8 μm as measured on the film surface before polishing. Measurement was attempted by the method. Since the pattern may not be detected if there are irregularities on the surface of the scribing wheel as a sample, the diamond film 14 of the scribing wheel was pretreated (precisely polished). In addition, since the size of the diamond crystal varies depending on the distance from the scribing wheel base material, a part of the diamond film is shaved in the thickness direction to expose the base material into a plurality of blocks having different distances from the base material. divided. Each block was irradiated with an electron beam, and an EBSD pattern formed by reflected electrons was captured as an image by a high sensitivity CCD camera, processed by an image processing apparatus, and crystal grains were mapped by a data analysis system.

According to the EBSD method, the following analysis methods A to D,
A: When calculating the average (arithmetic average) using the twin grain boundary as the crystal grain boundary B: When calculating the weighted average based on the area ratio using the twin grain boundary as the crystal grain boundary C: Crystallizing the twin grain boundary When calculating the average (arithmetic average) without using the grain boundary D: The measurement result varies greatly depending on the case where the weighted average based on the area ratio is calculated without using the twin grain boundary as the crystal grain boundary. The result obtained as the particle size at this time was almost A <C <B <D by the analysis method, but in any case, it was 2.5 μm or less. From this result, according to the EBSD method, a smaller numerical value is calculated than when the particle diameter is observed on the film surface. This is probably because when the diamond crystal grows to form a film, the grain size increases with the growth, so that no small crystal appears on the film surface.

  According to the above measurement, when the inside of a diamond film having an average particle diameter of 2 to 8 μm is measured by measurement on the film surface, the average particle diameter is 2.5 μm or less in any analysis method, although it depends on the analysis method. From this, even when the entire film surface is polished, if the average particle diameter is 3 μm or less, the average particle diameter on the surface is considered to be 2 to 10 μm. Therefore, even after the diamond film 14 is polished as shown in FIG. 2B, the average particle diameter of the surface can be estimated.

  Next, a second embodiment of the present invention will be described. Japanese Patent No. 3074143 proposes a scribing wheel in which a large number of grooves are formed at predetermined intervals on the circumferential surface of the scribing wheel, and a high penetration type is formed with protrusions therebetween. The present invention can also be applied to such a scribing wheel. FIG. 3A is a front view of the scribing wheel of this embodiment, FIG. 3B is an enlarged cross-sectional view of the previous ridge line portion, and FIG. 3C is an enlarged view of the circular portion indicated by the one-dot chain line in FIG. When manufacturing a scribing wheel, first, a through hole 32 serving as an axial hole is formed in the center of a disc 31 serving as a scribing wheel base material made of cemented carbide or ceramic as shown in FIG. 3A. Next, a shaft such as a motor is communicated with the through hole 32 and rotated around the central axis, and the entire circumference of the disk 31 is polished from both sides to form a V-shape to form a scribing wheel base 31. The V-shaped slope formed in this way is defined as a polishing surface 33. Also in this case, as in the first embodiment, a single-layer diamond film 34 is coated on the cutting edge portion of the scribing wheel by the CVD method and polished by the method described above. When the diamond film 34 is 20 μm, the groove 35 is formed within the thickness range of the diamond film 34 as shown in FIG. 3C. Since the depth of the groove of the scribing wheel for achieving the high penetration type is, for example, about 10 μm, the groove 35 is formed in the diamond film 34 to obtain a high penetration type scribing wheel.

  As described above, even if the grooves 35 are formed in the diamond film 34, since the diamond film is a single layer and the properties in the film are uniform, it is easy to uniformly process a large number of grooves, and scribe. At this time, it becomes difficult for the ridge line portion of the diamond film 34 to be worn or worn. Therefore, a scribing wheel having a longer life can be obtained.

  Alternatively, a scribing wheel may be formed by forming a groove in a V-shaped cutting edge portion of the scribing wheel in advance, and coating and polishing this scribing wheel with a diamond film by a CVD method.

  A state before and after polishing of the scribing wheel according to the embodiment will be described. Examples 1 to 3 are scribing wheels according to the first embodiment in which a single-layer diamond film is formed by chemical vapor deposition on a cemented carbide scribing wheel substrate having an outer diameter of 2 mm. In Example 1, the cutting edge angle before polishing is 110 °, and in the case of rough polishing, polishing is performed using a No. 8000 abrasive so that the cutting edge angle becomes 115 ° after the completion of rough polishing. Is polished to 120 ° after finishing polishing. The thickness d of the thinnest part near the ridgeline of the diamond film 14 is set to 20 μm, for example. The arithmetic average roughness Ra on the inclined surface on the ridge line portion and the line parallel to the ridge line a certain distance away from the ridge line portion in Example 1 was as shown in FIG. 4A.

  In Example 2, the blade edge angle before polishing was 125 °, which was polished using a No. 8000 abrasive so that it was 130 ° after rough polishing and No. 15000 was used so as to be 135 ° after final polishing. is there. In Example 2, the arithmetic average roughness Ra on the inclined surface on the ridge line portion and the line parallel to the ridge line separated from the ridge line by a certain distance was as shown in FIG. 4B.

  In Example 3, the blade angle was 140 ° before polishing, and was polished using a No. 8000 abrasive so that it was 145 ° after rough polishing and No. 15000 was 150 ° after final polishing using a No. 15000 abrasive. is there. Regarding Example 3, the arithmetic average roughness Ra on the inclined surface on the ridge line portion and the line parallel to the ridge line a certain distance from the ridge line portion was as shown in FIG. 4C.

  In Examples 1 to 3, the polishing process was possible without any chipping of the surface during polishing. In Examples 1 to 3, the arithmetic average roughness was reduced by performing rough polishing and final polishing, and the arithmetic average roughness after the final polishing was 0.022 μm on the slope of Example 1 at the maximum. Therefore, the end face accuracy of the brittle material substrate cut after scribing using this scribing wheel can be improved.

  The scribing wheel of the present invention can provide a scribing wheel that can cut out a brittle material substrate having high wear resistance and peeling resistance and high end face strength, and can be suitably used for a scribing apparatus.

DESCRIPTION OF SYMBOLS 10,30 Scribing wheel 11,31 Disk 12,32 Through-hole 13,33 Polishing surface 14,34 Diamond film 16 Circumferential surface 35 Groove

Claims (3)

A scribe line is formed along a circumferential portion, and a scribing wheel base material having a cutting edge composed of the ridge line and inclined surfaces on both sides of the ridge line,
Anda diamond film formed on the edge surface of the scribing wheel base,
A band-like region including a ridge line of the diamond film is defined as a polishing region, an average particle diameter of diamond particles in the polishing region is 2.5 μm or less, and a film thickness in the vicinity of the ridge line is 5 to 25 μm. Scribing wheel.   The scribing wheel according to claim 1, wherein an arithmetic average roughness Ra of the ridge line is 0.015 μm or less.   The scribing wheel according to claim 1, wherein the scribing wheel has a groove formed by cutting out the ridge portion at a predetermined interval, and a projection is provided between the grooves.