Grindstone and grinding wheel

Abstract

To provide a grindstone that is appropriate for processing difficult-to-machine materials and that is capable of reducing decline in its performance.SOLUTION: A grindstone is provided with a machining surface, the grindstone comprising multiple abrasive grain layers and multiple photocatalyst layers, wherein each abrasive grain layer contains abrasive grains and a first binding material for securing the abrasive grains, and each photocatalyst layer contains photocatalyst particles and a second binding material for securing the photocatalyst particles, and one side of each of the multiple abrasive grain layers and one side of each of the multiple photocatalyst layers are disposed in an alternating manner on the machining surface.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a grinding wheel comprising a grinding stone having a processing surface, an annular base having one end face with an annular groove formed therein, and a plurality of grinding stones arranged in a ring shape, each having a base end fixed in the annular groove and each having a grinding surface located at a tip end. [Background technology]

[0002] Chips for devices such as integrated circuits (ICs) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured, for example, by grinding the backside of a workpiece such as a wafer having multiple devices formed on its front side to thin it, and then cutting the workpiece to divide it along the boundaries of the multiple devices.

[0003] A grinding device for grinding a workpiece generally includes a chuck table for holding the workpiece and a spindle with a grinding wheel attached to its tip (see, for example, Patent Document 1). The grinding wheel includes an annular base having an end face on one side with an annular groove formed therein, and a plurality of grinding stones arranged in an annular shape, each with a base end fixed in the annular groove and each with a processing surface (grinding surface) located at its tip.

[0004] When thinning a workpiece in a grinding device, the workpiece is first held by a chuck table so that its backside is exposed. Then, by rotating both the chuck table and the spindle and bringing them closer together, the grinding surfaces of the multiple grinding wheels are rotated and pressed against the backside of the workpiece. This allows the workpiece to be ground by the multiple grinding wheels and thinned.

[0005] A cutting device for cutting a workpiece generally includes a chuck table for holding the workpiece and a spindle with a cutting blade attached to the tip. The cutting blade includes a grinding wheel having an annular shape, the outer surface of which becomes the processing surface (cutting surface).

[0006] When dividing a workpiece in a cutting device, the workpiece is first held by a chuck table, for example, via a dicing tape. Then, while rotating the spindle, the cutting blade penetrates the workpiece and cuts into the dicing tape. The chuck table and the spindle are then moved relative to each other, and the cutting surface of the grinding wheel is pressed against the boundary between multiple devices on the workpiece while rotating. This causes the grinding wheel to cut the workpiece and divide it.

[0007] When a workpiece is processed (for example, grinded or cut) in this way, processing debris is generated, and the grinding wheel and the workpiece are heated by frictional heat, which may result in a deterioration in the processing quality of the workpiece. Therefore, such processing is often performed while supplying water near the contact interface (processing point) between the grinding wheel and the workpiece to wash away processing debris and cool the grinding wheel and the workpiece.

[0008] The workpiece used in the manufacture of chips is made of, for example, silicon (Si). If the chip is a power device chip, the workpiece may be made of a wide bandgap semiconductor such as silicon carbide (SiC), gallium nitride (GaN), or gallium arsenide (GaAs).

[0009] However, wide bandgap semiconductors are often difficult to cut, and therefore, when they are processed to manufacture power device chips, the lifespan of tools including grinding wheels (e.g., grinding wheels or cutting blades) can be shortened, potentially increasing the cost of manufacturing the chips.

[0010] In light of this, it has been proposed to process a workpiece using a grinding wheel having photocatalytic particles (e.g., particles made of titanium oxide) dispersed throughout its entire surface, while irradiating the processing surface (e.g., grinding surface or cutting surface) with light (e.g., ultraviolet light) (see, for example, Patent Documents 2 and 3). In this case, water supplied near the processing point is decomposed to generate hydroxyl radicals, which oxidize the portion of the workpiece near the processing point. This weakens that portion of the workpiece, making it easier to process. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-288881 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-162915 [Patent Document 3] Japanese Patent Application Publication No. 2019-42886 Summary of the Invention [Problem to be solved by the invention]

[0012] A grinding wheel generally contains abrasive grains and a binder for fixing the abrasive grains. However, if photocatalytic particles are dispersed throughout the entire grinding wheel, the proportion of other components must be reduced, which may result in a deterioration in the performance of the grinding wheel. For example, if the proportion of abrasive grains in the grinding wheel is reduced, it may become difficult to process the workpiece using the grinding wheel. Furthermore, if the proportion of binder in the grinding wheel is reduced, the grinding wheel may become more susceptible to wear, shortening its lifespan.

[0013] In view of this, the present invention provides a grinding wheel that is suitable for machining difficult-to-cut materials and that prevents deterioration of the grinding performance. [Means for solving the problem]

[0014] According to one aspect of the present invention, there is provided a grinding wheel having a processing surface, the grinding wheel having a plurality of abrasive grain layers and a plurality of photocatalytic layers, each of the plurality of abrasive grain layers containing abrasive grains and a first binder for fixing the abrasive grains, and each of the plurality of photocatalytic layers containing photocatalytic particles and a second binder for fixing the photocatalytic particles, and one surface of each of the plurality of abrasive grain layers and one surface of each of the plurality of photocatalytic layers are arranged alternately on the processing surface.

[0015] The photocatalyst particles may be particles made of titanium oxide.The grinding stone of the present invention may have a circular ring shape whose outer surface serves as the processing surface.

[0016] According to another aspect of the present invention, there is provided a grinding wheel comprising an annular base having one end face on which an annular groove is formed, and a plurality of grinding stones each having a base end fixed in the annular groove so as to be arranged in an annular shape and each having a grinding surface located at a tip end, wherein each of the plurality of grinding stones has a plurality of abrasive grain layers and a plurality of photocatalytic layers, each of the plurality of abrasive grain layers containing abrasive grains and a first binder for fixing the abrasive grains, and each of the plurality of photocatalytic layers containing photocatalytic particles and a second binder for fixing the photocatalytic particles, and one side of each of the plurality of abrasive grain layers and one side of each of the plurality of photocatalytic layers are arranged alternately on the grinding surface. [Effects of the Invention]

[0017] The grinding wheel of the present invention has multiple abrasive grain layers and multiple photocatalyst layers arranged alternately on the processing surface. Each photocatalyst layer contains photocatalyst particles. Therefore, by using this grinding wheel to process a workpiece while irradiating the processing surface with light, it becomes easy to process difficult-to-cut materials.

[0018] In addition, this grinding wheel has multiple abrasive grain layers in addition to the multiple photocatalytic layers. Each abrasive grain layer can be a layer containing components (e.g., abrasive grains and binder) in a ratio suitable for processing the workpiece. Therefore, this grinding wheel can suppress performance degradation compared to a grinding wheel in which photocatalytic particles are dispersed throughout its entire surface. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a grinding wheel. [Figure 2] FIG. 2 is a perspective view schematically showing an example of a grinding stone provided on a grinding wheel. [Figure 3] FIG. 3 is a partially enlarged cross-sectional view schematically showing the structure of each of a plurality of abrasive grain layers and a plurality of photocatalyst layers included in the grindstone. [Figure 4] FIG. 4 is a perspective view schematically showing another example of a grinding stone provided on a grinding wheel. [Figure 5] FIG. 5 is a perspective view schematically showing an example of a grindstone provided on a cutting blade. [Figure 6] FIG. 6 is a perspective view schematically showing another example of a grindstone provided on a cutting blade. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described with reference to the accompanying drawings, which are provided to facilitate understanding of the present invention and do not necessarily accurately reflect the objects and / or methods in which the present invention is embodied.

[0021] Fig. 1 is a perspective view showing an example of a grinding wheel. The grinding wheel 2 shown in Fig. 1 has an annular base 4 made of metal (aluminum alloy, etc.) or resin, etc. This annular base 4 has one end face 4a and the other end face 4b that are generally parallel to each other. The other end face 4b is the face that is attached to the tip of a spindle provided in a grinding device.

[0022] An opening 4c is formed in the center of the annular base 4, penetrating the annular base 4 in its thickness direction. This opening 4c has a shape corresponding to a truncated cone whose diameter increases from the other end face 4b toward the one end face 4a. An annular groove 4d is formed in the one end face 4a of the annular base 4, along the outer periphery of the annular base 4, concentric with the opening 4c.

[0023] A plurality of grinding stones 6 are provided in the annular groove 4d so as to be arranged in a ring shape. Specifically, each grinding stone 6 is provided so that its base end is fixed in the annular groove 4d and its tip end has an exposed grinding surface 6a. In addition, each grinding stone 6 has, in a plan view, a rectangular parallelepiped shape extending parallel to a line tangent to the annular groove 4d, or a shape obtained by slightly curving this rectangular parallelepiped to fit along the annular groove 4d.

[0024] 2 is a perspective view schematically illustrating an example of a grinding wheel 6. This grinding wheel 6 has a plurality of abrasive grain layers 8 and a plurality of photocatalytic layers 10. Each abrasive grain layer 8 and each photocatalytic layer 10 has a shape corresponding to a substantially equal rectangular plate. In addition, in the grinding wheel 6, the abrasive grain layers 8 and the photocatalytic layers 10 are alternately stacked in the length direction, with an abrasive grain layer 8 located at each end.

[0025] In other words, the surfaces 8a of the multiple abrasive grain layers 8 and the surfaces 10a of the multiple photocatalytic layers 10 are alternately arranged on the grinding surface 6a along the length direction of the grinding wheel 6, and are arranged so that the surfaces 8a of the abrasive grain layers 8 are located at both ends of the grinding surface 6a in the length direction of the grinding wheel 6. The total number of the multiple abrasive grain layers 8 and the multiple photocatalytic layers 10 is, for example, an odd number between 5 and 25.

[0026] 3 is a partially enlarged cross-sectional view schematically showing the structure of each of the plurality of abrasive grain layers 8 and the plurality of photocatalyst layers 10. Each abrasive grain layer 8 contains abrasive grains 8b and a first binder 8c for fixing the abrasive grains 8b. Each photocatalyst layer 10 contains photocatalyst particles 10b and a second binder 10c for fixing the photocatalyst particles 10b.

[0027] Each abrasive layer 8 does not substantially contain photocatalytic particles similar to the photocatalytic particles 10b, and each photocatalytic layer 10 does not substantially contain abrasive particles similar to the abrasive particles 8b. Each abrasive layer 8 and / or each photocatalytic particle 10b may contain components other than the above-mentioned components (for example, filler).

[0028] The abrasive grains 8b are particles made of, for example, diamond or cBN (cubic boron nitride). The photocatalyst particles 10b are particles made of, for example, a metal oxide such as titanium oxide (TiO2), tungsten oxide (WO3), strontium titanate (SrTiO3), or zinc oxide (ZnO), or a metal sulfide such as zinc sulfide (ZnS) or cadmium sulfide (CdS). The particle diameter of each photocatalyst particle is, for example, 10 nm to 1000 nm.

[0029] Each of the first bonding material 8c and the second bonding material 10c is, for example, a vitrified bond whose main component is glass such as silicon oxide (SiO2), a metal bond whose main component is metal such as copper (Cu), or a resin bond whose main component is resin such as phenolic resin. The first bonding material 8c and the second bonding material 10c may be made of the same material or different materials.

[0030] However, the grinding wheel 6 is manufactured by, for example, stacking a plurality of abrasive grain layers 8 and a plurality of photocatalyst layers 10 and then sintering them. Therefore, from the viewpoint of preventing damage to the grinding wheel 6 when grinding a workpiece using the grinding wheel 2, it is preferable that the first binder 8c and the second binder 10c are made of the same material.

[0031] In this case, the plurality of abrasive grain layers 8 and the plurality of photocatalytic layers 10 are firmly bonded to each other by sintering. Therefore, in this case, when the grinding wheel 2 is used to grind a workpiece, cracks are less likely to occur at the interface between the abrasive grain layers 8 and the photocatalytic layers 10, and the grinding stone 6 is less likely to break.

[0032] On the other hand, from the viewpoint of facilitating the discharge of grinding chips generated during grinding of the workpiece from the vicinity of the processing point, it is preferable that the second binder 10c be made of a material that is more easily consumed than the first binder 8c. For example, from this viewpoint, it is preferable that the first binder 8c be a vitrified bond and the second binder 10c be a resin bond.

[0033] In this case, when the workpiece is ground using the grinding wheel 2, one surface 10a of the photocatalytic layer 10 is worn more severely than one surface 8a of the abrasive grain layer 8, which makes it easier for recesses (chip pockets) to be formed on the grinding surface 6a of the grinding wheel 6. Therefore, in this case, grinding debris generated during this grinding is more likely to pass through the chip pockets and be discharged from the vicinity of the processing point.

[0034] 1, the annular base 4 is formed with a plurality of water supply passages 4e that penetrate the annular base 4 so as to open at one end face 4a and the other end face 4b. These water supply passages 4e are provided at approximately equal angular intervals along the circumferential direction of the annular base 4.

[0035] When grinding a workpiece using the grinding wheel 2, first, the grinding wheel 2 is rotated around a straight line passing through the center of the opening 4c and along its thickness direction as the rotation axis, i.e., the grinding surface 6a of each grinding stone 6 is rotated, and water is supplied to one end face 4a of the annular base 4 through each water supply passage 4e.

[0036] Then, while continuing the rotation of the grinding surface 6a of each grinding wheel 6 and the supply of water, light (e.g., ultraviolet light) is irradiated onto the grinding surface 6a of one of the multiple grinding wheels 6 that is located in a predetermined direction when viewed from the center of the opening 4c, and the grinding surface 6a of another grinding wheel 6 that is located in a direction different from the predetermined direction is pressed against the workpiece. As a result, the workpiece is ground with water being supplied to the processing point.

[0037] Here, each grinding wheel 6 has a plurality of abrasive grain layers 8 and a plurality of photocatalyst layers 10 arranged alternately on the grinding surface 6a. Each photocatalyst layer 10 contains photocatalyst particles 10b. Therefore, by using this grinding wheel 6 to process a workpiece while irradiating the grinding surface 6a with light, it becomes easy to process difficult-to-cut materials.

[0038] Furthermore, in this grinding wheel 6, a plurality of abrasive grain layers 8 are provided in addition to the plurality of photocatalytic layers 10. Each abrasive grain layer 8 can be a layer containing components (e.g., abrasive grains and a binder) in a ratio suitable for processing the workpiece. Therefore, in this grinding wheel 6, deterioration of performance can be suppressed compared to a grinding wheel in which photocatalytic particles are dispersed throughout its entire area.

[0039] The above-described content is one aspect of the present invention, and the present invention is not limited to the above-described content. For example, a grinding stone having a structure different from that of grinding stone 6 may be applied as the grinding stone provided on grinding wheel 2.

[0040] Fig. 4 is a perspective view schematically showing an example of a grinding wheel provided on the grinding wheel 2 and having a structure different from that of the grinding wheel 6. In the grinding wheel 12 shown in Fig. 4, abrasive grain layers 14 and photocatalytic layers 16 are alternately stacked in the width direction, with abrasive grain layers 14 positioned at both ends.

[0041] In other words, the surfaces 14a of the plurality of abrasive grain layers 14 and the surfaces 16a of the plurality of photocatalytic layers 16 are alternately arranged on the processing surface (grinding surface) 12a along the width direction of the grinding wheel 12, and are arranged so that the surfaces 14a of the abrasive grain layers 14 are located at both ends of the grinding surface 12a in the width direction of the grinding wheel 12. Each abrasive grain layer 14 has the same internal structure as the abrasive grain layer 8 described above. Each photocatalytic layer 16 has the same internal structure as the photocatalytic layer 10 described above.

[0042] The grindstone of the present invention may also be provided on a cutting blade. Fig. 5 is a perspective view schematically showing an example of a grindstone provided on a cutting blade. The grindstone 18 shown in Fig. 5 has a circular ring shape with a circular opening 18a at its center and its outer surface serving as a processing surface (cutting surface) 18b.

[0043] The grinding wheel 18 has a plurality of abrasive grain layers 20 and a plurality of photocatalytic layers 22. Each abrasive grain layer 20 and each photocatalytic layer 22 has a shape that corresponds to a substantially equal circular plate. In addition, the grinding wheel 18 is stacked such that the abrasive grain layers 20 and the photocatalytic layers 22 alternate in the thickness direction, with an abrasive grain layer 20 located at each end of the thickness direction.

[0044] In other words, the surfaces 20a of the multiple abrasive grain layers 20 and the surfaces 22a of the multiple photocatalytic layers 22 are alternately arranged on the cutting surface 18b along the thickness direction of the grinding wheel 18, and are arranged so that the surfaces 20a of the abrasive grain layers 20 are located on both ends of the cutting surface 18b in the thickness direction of the grinding wheel 18. Each abrasive grain layer 20 has the same internal structure as the abrasive grain layer 8 described above. Each photocatalytic layer 22 has the same internal structure as the photocatalytic layer 10 described above.

[0045] When cutting a workpiece using a cutting blade equipped with grinding wheel 18, first, the cutting blade is rotated around a straight line passing through the center of opening 18a and along its thickness direction as the rotation axis, i.e., the cutting surface 18b of grinding wheel 18 is rotated and water is supplied to this cutting surface 18b.

[0046] Then, while continuing the rotation of cutting surface 18b of grindstone 18 and the supply of water, light (e.g., ultraviolet light) is irradiated onto an area of ​​cutting surface 18b that is positioned in a predetermined direction when viewed from the center of opening 18a, and an area that is positioned in a direction different from the predetermined direction is pressed against the workpiece. As a result, the workpiece is cut with water being supplied to the processing point.

[0047] The grinding wheel of the present invention may be laminated so that the photocatalytic layer 10, 16, 22 is located on at least one of its ends. That is, the surfaces 8a, 14a, 20a of the plurality of abrasive grain layers 8, 14, 20 and the surfaces 10a, 16a, 22a of the plurality of photocatalytic layers 10, 16, 22 may be arranged so that the surfaces 10a, 16a, 22a of the photocatalytic layers 10, 16, 22 are located on at least one of their ends.

[0048] However, when grinding a workpiece using a grinding wheel 2 equipped with multiple grinding stones, the load on both ends of each grinding stone tends to be large. Furthermore, when cutting a workpiece using a cutting blade equipped with grinding stones, processing debris tends to accumulate on both ends of the cutting blade. Therefore, from the viewpoint of improving the processing quality of the workpiece, it is preferable to stack multiple abrasive grain layers 8, 14, 20 and multiple photocatalyst layers 10, 16, 22 so that the abrasive grain layers 8, 14, 20 are located on both ends of the grinding stone.

[0049] Furthermore, a grindstone having a different structure from grindstone 18 may be applied as the grindstone provided on the cutting blade. Fig. 6 is a perspective view schematically showing an example of a grindstone provided on the cutting blade and having a different structure from grindstone 18. Grindstone 24 shown in Fig. 6 has a circular ring shape with a circular opening 24a in its center and its outer surface serving as a processing surface (cutting surface) 24b.

[0050] The grinding wheel 24 has a plurality of abrasive grain layers 26 and a plurality of photocatalytic layers 28. Each abrasive grain layer 26 and each photocatalytic layer 28 has a shape corresponding to a substantially equal circular arc plate. In addition, the grinding wheel 24 has the abrasive grain layers 26 and photocatalytic layers 28 alternately stacked in the circumferential direction.

[0051] In other words, the surfaces 26a of the plurality of abrasive grain layers 26 and the surfaces 28a of the plurality of photocatalytic layers 28 are arranged alternately on the cutting surface 24b along the width direction of the grinding wheel 24. Each abrasive grain layer 26 has the same internal structure as the above-described abrasive grain layer 8. Each photocatalytic layer 28 has the same internal structure as the above-described photocatalytic layer 10.

[0052] In addition, the structures and methods according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0053] 2: Grinding wheel 4: Annular base (4a: one end face, 4b: the other end face, 4c: opening) (4d: annular groove, 4e: water supply channel) 6: Grinding wheel (6a: Processing surface (grinding surface)) 8: Abrasive layer (8a: one surface, 8b: abrasive grains, 8c: first binder) 10: Photocatalytic layer (10a: one surface, 10b: photocatalytic particles, 10c: second binder) 12: Grinding wheel (12a: Processing surface (grinding surface)) 14: Abrasive layer (14a: one side) 16: Photocatalyst layer (16a: one side) 18: Grindstone (18a: opening, 18b: processing surface (cutting surface)) 20: Abrasive layer (20a: one side) 22: Photocatalyst layer (22a: one side) 24: Grindstone (24a: opening, 24b: processing surface (cutting surface)) 26: Abrasive layer (26a: one side) 28: Photocatalyst layer (28a: one side)

Claims

1. A grinding wheel having a processing surface, Abrasive grain layers and photocatalytic layers are included, each of the plurality of abrasive grain layers includes abrasive grains and a first binder for fixing the abrasive grains; Each of the plurality of photocatalyst layers includes photocatalyst particles and a second binder for fixing the photocatalyst particles, The grindstone, wherein one surface of each of the plurality of abrasive grain layers and one surface of each of the plurality of photocatalytic layers are arranged alternately on the processing surface.

2. 2. The grindstone according to claim 1, wherein the photocatalytic particles are particles made of titanium oxide.

3. 3. The grinding wheel according to claim 1, wherein the outer surface of the grinding wheel has a circular ring shape that serves as the processing surface.

4. A grinding wheel comprising: an annular base having an end surface on one side of which an annular groove is formed; and a plurality of grinding stones, each having a base end fixed in the annular groove so as to be arranged in an annular shape and each having a grinding surface located at a tip end thereof; Each of the plurality of grinding wheels has a plurality of abrasive grain layers and a plurality of photocatalytic layers, each of the plurality of abrasive grain layers includes abrasive grains and a first binder for fixing the abrasive grains; Each of the plurality of photocatalyst layers includes photocatalyst particles and a second binder for fixing the photocatalyst particles, A grinding wheel, wherein one surface of each of the plurality of abrasive grain layers and one surface of each of the plurality of photocatalyst layers are arranged alternately on the grinding surface.

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