Electroformed grinding wheel

Abstract

To provide an electroformed grindstone that can promote self-sharpening while suppressing a decrease in strength.SOLUTION: An electroformed grindstone has a grindstone part including abrasive grains and a binder for fixing the abrasive grains. The binder is composed of a Ni-Co alloy and contains a fluorine-based resin. The Co content in the binder may be 5 wt.% or more and 30.2 wt.% or less. The content of the fluorine-based resin in the binder may be 3 vol% or more and less than 40 vol%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electroformed grinding wheel used for cutting a workpiece or the like.

Background Art

[0002] By dividing a wafer on which a plurality of devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are formed, a plurality of device chips each having a device are manufactured. Further, after mounting a plurality of device chips on a predetermined substrate, the mounted device chips are covered with a sealing material (mold resin) made of resin to obtain a package substrate. By dividing this package substrate, a packaged device having a plurality of packaged device chips is manufactured. The device chips and the packaged devices are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] When dividing a workpiece such as the above-mentioned wafer or package substrate, a cutting device is used. The cutting device includes a chuck table for holding the workpiece and a cutting unit for performing cutting on the workpiece. The cutting unit includes a spindle that functions as a rotation axis, and a cutting blade is mounted on the tip of the spindle.

[0004] As the cutting blade, an electroformed grinding wheel including an annular grinding wheel portion (cutting edge) can be used. For example, the grinding wheel portion of the electroformed grinding wheel is formed by fixing diamond abrasive grains with a nickel layer (Ni plating layer) formed by electroplating (see Patent Document 1). The workpiece is held by the chuck table of the cutting device, and the grinding wheel portion is cut into the workpiece while rotating the electroformed grinding wheel, so that the workpiece is cut and divided (see Patent Document 2).

[0005] When an electroformed grinding wheel is used to cut a workpiece, the abrasive grains exposed from the Ni plating layer come into contact with the workpiece and cut it. After a certain period of time, the Ni plating layer wears down, the exposed abrasive grains fall off, and new abrasive grains embedded within the Ni plating layer become exposed. This phenomenon is called self-sharpening, and it is through self-sharpening that the cutting performance of the electroformed grinding wheel is maintained.

[0006] However, the nickel plating layer has a strong ability to hold abrasive grains, and even if the nickel plating layer wears down, the abrasive grains are less likely to fall off. Therefore, electroformed grinding wheels in which abrasive grains are fixed by the nickel plating layer have the characteristic of being less prone to spontaneous sharpening. If cutting of the workpiece continues without spontaneous sharpening occurring at an appropriate frequency, the tips of the abrasive grains exposed from the nickel plating layer will wear down and deform due to contact with the workpiece. This increases the pressure (machining load) on the workpiece during cutting, making machining defects more likely.

[0007] Therefore, a method has been proposed to control the shedding of abrasive grains by incorporating a fluororesin into the Ni plating layer of an electroformed grinding wheel (see Patent Document 3). When a fluororesin is dispersed in the Ni plating layer, abrasive grains are more easily detached from the Ni plating layer when the electroformed grinding wheel is used to cut into the workpiece, thereby promoting self-sharpening. This maintains the sharpness of the electroformed grinding wheel and suppresses the occurrence of machining defects. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2000-87282 [Patent Document 2] Japanese Patent Publication No. 2005-51094 [Patent Document 3] Japanese Patent Publication No. 2009-119559 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Dispersing fluororesin in the Ni plating layer promotes self-sharpening of the cutting edge, but it also reduces the hardness and rigidity of the Ni plating layer, making the electroformed grinding wheel more prone to warping. When machining is performed using such an electroformed grinding wheel, chipping or cracking may occur, or the grinding wheel may meander during cutting, resulting in unintended areas of the workpiece being cut. In other words, incorporating fluororesin into the Ni plating layer reduces the strength of the electroformed grinding wheel, leading to problems such as breakage of the grinding wheel and machining defects.

[0010] This invention has been made in view of the above problems, and aims to provide an electroformed grinding wheel that can promote self-sharpening while suppressing a decrease in strength. [Means for solving the problem]

[0011] According to one aspect of the present invention, the present invention comprises a grinding wheel portion including abrasive grains and a binder for fixing the abrasive grains, wherein the binder is made of a Ni-Co alloy and contains a fluororesin. Furthermore, the Co content in the binder is 5 wt% or more and 30.2 wt% or less. Electroformed grinding wheels are provided.

[0012] Preferably, the Co content in the binder is 8.1 wt% or more. Also preferably, the fluororesin content in the binder is 3 vol% or more. 35vol% or less Preferably, the average particle size of the abrasive grains is 1 μm or more and 80 μm or less, and the average particle size of the fluororesin is 0.1 μm or more and 20 μm or less.

[0013] Preferably, the electroformed grinding wheel comprises an annular base and an annular grinding wheel portion formed along the outer periphery of the base. Preferably, the electroformed grinding wheel is composed of the annular grinding wheel portion. [Effects of the Invention]

[0014] In one aspect of the present invention, an electroformed grinding wheel is constructed using a binder made of a Ni-Co alloy containing a fluororesin to fix the abrasive grains. The binder, being made of a Ni-Co alloy with high hardness and rigidity, maintains the strength of the electroformed grinding wheel, while the fluororesin accelerates the shedding of the abrasive grains. This makes it possible to suppress the decrease in strength of the electroformed grinding wheel while promoting self-sharpening, thereby preventing damage to the electroformed grinding wheel and the occurrence of processing defects. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1(A) is a perspective view showing a hub-type electroformed grinding wheel, and Figure 1(B) is a perspective view showing a washer-type electroformed grinding wheel. [Figure 2] This is a perspective view showing a cutting machine. [Figure 3] This is a perspective view showing the cutting unit. [Figure 4] This is an enlarged cross-sectional view showing the tip of the grinding wheel section. [Figure 5] This is a partial cross-sectional front view showing a manufacturing apparatus for producing hub-type electroformed grinding wheels. [Figure 6] Figure 6(A) is a cross-sectional view showing an annular base on which a Ni-Co alloy plating layer has been formed, and Figure 6(B) is a cross-sectional view showing an annular base on which the outer periphery has been etched. [Figure 7] This is a partial cross-sectional front view showing a manufacturing apparatus for producing washer-type electroformed grinding wheels. [Figure 8] Figure 8(A) is a cross-sectional view showing a disc-shaped base on which a Ni-Co alloy plating layer is formed, and Figure 8(B) is a cross-sectional view showing the Ni-Co alloy plating layer separated from the disc-shaped base. [Figure 9] Figure 9(A) is a graph showing the relationship between the Co content and the degree of warping of the electroformed grinding wheel, Figure 9(B) is a graph showing the relationship between the Co content and the hardness of the electroformed grinding wheel, and Figure 9(C) is a graph showing the relationship between the Co content and the rigidity of the electroformed grinding wheel. [Figure 10]FIG. 10(A) is a graph showing the relationship between the content of the fluororesin and the rigidity of the electroformed grinding wheel, and FIG. 10(B) is a graph showing the relationship between the content of the fluororesin and the maximum chipping size.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, a configuration example of the electroformed grinding wheel according to the present embodiment will be described. The electroformed grinding wheel according to the present embodiment can be used as a cutting blade or the like for cutting a workpiece.

[0017] FIG. 1(A) is a perspective view showing a hub-type electroformed grinding wheel 11. The electroformed grinding wheel 11 includes an annular base 13 and an annular grinding portion 15 formed along the outer peripheral edge of the base 13.

[0018] For example, the base 13 is made of a metal mainly composed of aluminum and includes a front surface 13a and a back surface 13b. A columnar through-hole 13c penetrating from the front surface 13a to the back surface 13b of the base 13 is provided so as to penetrate the base 13 in the thickness direction at the central portion of the base 13. Further, an annular convex portion 13d protruding from the front surface 13a of the base 13 in the thickness direction of the base 13 is provided around the through-hole 13c.

[0019] An annular grinding portion 15 is provided along the outer peripheral edge of the base 13 on the back surface 13b side of the base 13. Note that the outer diameter of the grinding portion 15 is larger than the outer diameter of the base 13, and the grinding portion 15 is formed so as to protrude radially outward from the outer peripheral edge of the base 13.

[0020] FIG. 1(B) is a perspective view showing a washer-type electroformed grinding wheel 21. The electroformed grinding wheel 21 is composed only of an annular grinding portion 23. The grinding portion 23 includes a front surface 23a and a back surface 23b. Further, a columnar through-hole 23c penetrating from the front surface 23a to the back surface 23b of the grinding portion 23 is provided so as to penetrate the grinding portion 2 in the thickness direction at the central portion of the grinding portion 23.

[0021] For example, electroformed grinding wheels 11 and 21 are used as cutting blades to cut a workpiece. Specifically, electroformed grinding wheel 11 is a hub-type cutting blade (hub blade) in which the grinding wheel portion 15 functions as an annular cutting edge. Electroformed grinding wheel 21 is a washer-type cutting blade (washer blade) in which the entire wheel functions as an annular cutting edge. Electroformed grinding wheels 11 and 21 are mounted on a cutting device to cut a workpiece.

[0022] Figure 2 is a perspective view showing the cutting device 2. The cutting device 2 cuts the workpiece 31 using an electroformed grinding wheel 11 or an electroformed grinding wheel 21. In Figure 3, the X-axis direction (machining feed direction, first horizontal direction, left-right direction) and the Y-axis direction (indexing feed direction, second horizontal direction, front-back direction) are perpendicular to each other. The Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0023] The cutting device 2 includes a base 4 that supports or houses each component that makes up the cutting device 2. A cover 6 is provided on the upper side of the base 4, covering the upper surface of the base 4. Inside the cover 6, a space (processing chamber) is formed where the workpiece 31 is processed, and a cutting unit 8 for cutting the workpiece 31 is arranged in the processing chamber.

[0024] The cutting unit 8 is connected to a ball screw type moving mechanism (not shown). This moving mechanism moves the cutting unit 8 along the Y-axis and also raises and lowers the cutting unit 8 along the Z-axis. The cutting unit 8 is also fitted with an electroformed grinding wheel 11 (see Figure 1(A)) or an electroformed grinding wheel 21 (see Figure 1(B)). As an example, the case in which the cutting unit 8 is fitted with an electroformed grinding wheel 11 and the cutting device 2 processes the workpiece 31 using the electroformed grinding wheel 11 will be described below.

[0025] Figure 3 is a perspective view showing the cutting unit 8. The cutting unit 8 comprises a hollow, cylindrical housing 10. The housing 10 houses a cylindrical spindle 12 arranged along the Y-axis. The tip (one end) of the spindle 12 is exposed to the outside of the housing 10. A rotational drive source (not shown), such as a motor, is connected to the base (other end) of the spindle 12 to rotate the spindle 12.

[0026] A mount 14 is fixed to the tip of the spindle 12. The mount 14 comprises a disc-shaped flange portion 16 and a cylindrical support shaft (boss portion) 18 that protrudes from the center of the surface 16a of the flange portion 16. On the outer circumference of the flange portion 16, on the surface 16a side, an annular projection 16b is provided along the outer edge of the flange portion 16, protruding from the surface 16a. The tip surface of the projection 16b is formed to be approximately parallel to the surface 16a. In addition, a threaded portion 18a is formed on the outer circumference of the support shaft 18.

[0027] An annular fixing nut 20 is attached to the support shaft 18. A cylindrical opening 20a is formed in the center of the fixing nut 20, penetrating it in the thickness direction. On the side surface (inner circumferential surface) of the fixing nut 20 that is exposed inside the opening 20a, a screw groove is formed that corresponds to the threaded portion 18a of the support shaft 18.

[0028] When the support shaft 18 is inserted into the through hole 13c of the base 13 of the electroformed grinding wheel 11, the electroformed grinding wheel 11 is mounted on the tip (mount 14) of the spindle 12. The protrusion 13d of the base 13 corresponds to the gripping portion that holds the electroformed grinding wheel 11 when it is mounted.

[0029] With the electroformed grinding wheel 11 mounted on the mount 14, when the fixing nut 20 is tightened onto the threaded portion 18a of the support shaft 18, the electroformed grinding wheel 11 is clamped between the tip surface of the protrusion 16b of the flange portion 16 and the fixing nut 20. This fixes the electroformed grinding wheel 11 to the tip of the spindle 12 (mount 14). The electroformed grinding wheel 11 then rotates around a rotation axis that is roughly parallel to the Y-axis direction, power transmitted from the rotation drive source via the spindle 12 and mount 14.

[0030] As shown in Figure 2, a chuck table (holding table) 22 for holding the workpiece 31 is provided below the cutting unit 8. The upper surface of the chuck table 22 is a flat surface that is generally parallel to the X-axis and Y-axis directions, and constitutes a holding surface 22a for holding the workpiece 31. The holding surface 22a is connected to a suction source (not shown), such as an ejector, via a flow path (not shown), a valve (not shown), etc., formed inside the chuck table 22.

[0031] The chuck table 22 is connected to a ball screw type moving mechanism (not shown) and a rotational drive source such as a motor. The moving mechanism moves the chuck table 22 along the X-axis. The rotational drive source rotates the chuck table 22 around a rotation axis that is approximately parallel to the Z-axis.

[0032] A cassette elevator 24, configured to move up and down along the Z-axis, is provided at the front corner of the base 4. A cassette 26 capable of accommodating a workpiece 31 is placed on the cassette elevator 24. The cassette elevator 24 adjusts the height of the cassette 26 so that the workpiece 31 can be properly unloaded from and loaded into the cassette 26.

[0033] A transport mechanism (not shown) for transporting the workpiece 31 is provided near the cassette elevator 24. This transport mechanism transports the workpiece 31 before processing from the cassette 26 onto the chuck table 22, and also transports the workpiece 31 processed by the cutting unit 8 back into the cassette 26.

[0034] The front 6a side of the cover 6 is provided with a display unit (display device) 28 that displays various information related to the cutting device 2. The display unit 28 displays information related to the processing of the workpiece 31 (processing conditions, processing status, etc.) and an image of the workpiece 31 held by the chuck table 22.

[0035] For example, the display unit 28 is configured as a touch panel display. In this case, the display unit 28 becomes the user interface, and the operator can input information such as machining conditions to the cutting device 2 by touching the display unit 28. In other words, the display unit 28 also functions as an input unit (input device) for inputting information to the cutting device 2. However, the input unit may be provided separately and independently of the display unit 28. For example, a keyboard, mouse, etc., can be used as the input unit.

[0036] A control unit (control device) 30 for controlling the cutting device 2 is provided inside or outside the cutting device 2. The control unit 30 is connected to each component of the cutting device 2 (cutting unit 8, chuck table 22, cassette elevator 24, display unit 28, etc.) and generates control signals to control the operation of each component.

[0037] For example, the control unit 30 is configured by a computer. Specifically, the control unit 30 comprises a processing unit that performs calculations and other processing necessary for controlling the cutting device 2, and a storage unit that stores various information (data, programs, etc.) used for controlling the cutting device 2. The processing unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memory such as ROM (Read Only Memory) and RAM (Random Access Memory).

[0038] The workpiece 31, contained in the cassette 26, is transported onto the chuck table 22 by the transport mechanism. With the workpiece 31 positioned on the chuck table 22, when the suction force (negative pressure) of the suction source is applied to the holding surface 22a, the workpiece 31 is held in place by the chuck table 22. The workpiece 31, held by the chuck table 22, is cut by the electroformed grinding wheel 11 mounted on the cutting unit 8. After processing, the workpiece 31 is transported by the transport mechanism and placed back into the cassette 26.

[0039] When cutting the workpiece 31 with the electroformed grinding wheel 11, first, the height (position in the Z-axis direction) of the cutting unit 8 is adjusted so that the lower end of the electroformed grinding wheel 11 is positioned below the upper surface of the workpiece 31. Also, the position of the cutting unit 8 in the Y-axis direction is adjusted so that the electroformed grinding wheel 11 cuts into the workpiece 31 at the desired position. In this state, when the chuck table 22 is moved along the X-axis direction while the electroformed grinding wheel 11 is rotated, the grinding wheel portion 15 (see Figure 3) of the electroformed grinding wheel 11 cuts into the workpiece 31, and the workpiece 31 is cut.

[0040] Furthermore, the cutting unit 8 is equipped with a nozzle (not shown) for supplying a liquid (cutting fluid) such as pure water to the electroformed grinding wheel 11 and the workpiece 31. During cutting, the cutting fluid is supplied to the electroformed grinding wheel 11 and the workpiece 31 through the nozzle. This cools the electroformed grinding wheel 11 and the workpiece 31, and washes away the debris (cutting chips) generated by the cutting process.

[0041] There are no restrictions on the material, shape, structure, size, etc., of the workpiece 31 cut by the cutting device 2. For example, the workpiece 31 may be a wafer made of semiconductors (Si, GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. Also, the workpiece 31 may be a package substrate such as a CSP (Chip Size Package) substrate or a QFN (Quad Flat Non-leaded package) substrate.

[0042] Furthermore, although the above describes the case where the workpiece 31 is cut by the electroformed grinding wheel 11, the cutting device 2 can also cut the workpiece 31 using the electroformed grinding wheel 21 (see Figure 1(B)). In this case, the electroformed grinding wheel 21 is mounted on the cutting unit 8. The workpiece 31 is then cut by rotating the electroformed grinding wheel 21 and cutting into it.

[0043] Figure 4 is an enlarged cross-sectional view showing the tip portions of the grinding wheel sections 15 and 23. Each grinding wheel section 15 and 23 contains abrasive grains 41 and a binder (bonding material) 43 that fixes the abrasive grains 41. There are no restrictions on the material and size of the abrasive grains 41. For example, by using abrasive grains 41 made of diamond, cubic boron nitride (cBN), etc., with an average particle size of 1 μm or more and 80 μm or less, good cutting of the workpiece 31 is possible.

[0044] When the electroformed grinding wheels 11 and 21 (see Figures 1(A) and 1(B)) are used to cut into the workpiece 31, the abrasive grains 41 exposed from the surface of the binder 43 come into contact with the workpiece 31 and cut it. After the cutting of the workpiece 31 by the electroformed grinding wheels 11 and 21 continues for a certain period of time, the binder 43 wears down, the exposed abrasive grains 41 fall off, and new abrasive grains embedded inside the binder 43 become exposed. This phenomenon is called self-sharpening, and the sharpness of the electroformed grinding wheels 11 and 21 is maintained by self-sharpening.

[0045] Furthermore, the binder 43 contains granular fluororesin 45. For example, as the fluororesin 45, resins such as PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), FEP (perfluoroethylenepropene copolymer), and ETFE (ethylenetetrafluoroethylene copolymer) are dispersed in the binder 43.

[0046] When a fluororesin 45 is included in the binder 43, the strength of the region within the binder 43 where the fluororesin 45 is present is locally reduced. As a result, when cutting the workpiece 31 with the electroformed grinding wheels 11 and 21, wear of the binder 43 and shedding of abrasive grains 41 are more likely to occur. Consequently, self-sharpening is promoted, and the cutting performance of the electroformed grinding wheels 11 and 21 is maintained.

[0047] However, if the binder 43 is a Ni plating layer or the like, dispersing the fluororesin 45 in the binder 43 reduces the hardness and rigidity of the binder 43, making the electroformed grinding wheels 11 and 21 more prone to warping. When cutting is performed using such electroformed grinding wheels 11 and 21, chipping or cracking may occur in the electroformed grinding wheels 11 and 21, or the electroformed grinding wheels 11 and 21 may meander during cutting of the workpiece 31, causing unintended areas of the workpiece 31 to be cut.

[0048] Therefore, in this embodiment, a binder 43 made of an alloy containing nickel and cobalt (Ni-Co alloy) is used. Specifically, a layer made of Ni-Co alloy formed by electrodeposition (Ni-Co alloy plating layer) is used as the binder 43. The binder 43 made of Ni-Co alloy has higher strength compared to binders made of Ni plating layers, etc. Therefore, even if a fluororesin 45 is added to the binder 43 made of Ni-Co alloy, the decrease in strength of the binder 43 is kept to a minimum so as not to cause damage to the electroformed grinding wheels 11 and 21 or processing defects. In other words, electroformed grinding wheels 11 and 21 can be obtained that promote self-sharpening while suppressing a decrease in strength.

[0049] There are no restrictions on the size of the fluororesin 45. For example, in order to maintain the effect of promoting self-sharpening while suppressing an extreme decrease in the strength of the binder 43 made of Ni-Co alloy, the average particle size of the fluororesin 45 is set to be between 0.1 μm and 20 μm.

[0050] Next, an example of a method for manufacturing electroformed grinding wheels 11 and 21 containing a binder 43 made of Ni-Co alloy will be described. Electroformed grinding wheels 11 and 21 are manufactured, for example, using electroplating. The following describes in detail the procedure for manufacturing electroformed grinding wheels 11 and 21 using a manufacturing apparatus 40 (see Figures 5 and 7).

[0051] Figure 5 is a partial cross-sectional front view showing a manufacturing apparatus 40 for producing hub-type electroformed grinding wheels. The manufacturing apparatus 40 includes a plating bath 42 for storing a plating solution 44. The plating solution 44 is an electrolyte containing Ni and Co. Abrasive particles are dispersed in the plating solution 44. In addition, a solution 46 containing a fluororesin is added to the plating solution 44.

[0052] A plate-shaped electrode 48 made of Ni and an annular base 51 are immersed in the plating solution 44. The base 51 is formed to correspond to the shape of the base 13 (see Figure 1(A)) as it will ultimately be used as the base 13 of the electroformed grinding wheel 11. A mask 53 is also formed on the base 51 so as to cover it. The mask 53 has an annular opening that corresponds to the shape of the grinding wheel portion 15 (see Figure 1(A)), and a part of the base 51 is exposed inside the opening of the mask 53.

[0053] The electrode 48 and the base 51 are connected to the DC power supply 50. Specifically, the electrode 48 is connected to the positive terminal (positive electrode) of the DC power supply 50. The base 51 is connected to the negative terminal (negative electrode) of the DC power supply 50 via the switch 52.

[0054] Furthermore, a fan 54 is immersed in the plating solution 44. A rotational drive source 56, such as a motor, is connected to the fan 54. When the fan 54 is rotated by the rotational drive source 56, the plating solution 44 is agitated, and the abrasive particles and fluororesin contained in the plating solution 44 are dispersed fairly uniformly.

[0055] When the switch 52 is turned on while the plating solution 44 is stirred by the fan 54, the base 51 functions as the cathode and the electrode 48 as the anode, and a direct current flows through the plating solution 44. As a result, a Ni-Co alloy plating layer containing abrasive grains and fluororesin is electrodeposited onto the area of ​​the base 51 that is exposed and not covered by the mask 53. After a Ni-Co alloy plating layer of the desired thickness is formed on the base 51, the mask 53 is removed from the base 51.

[0056] Figure 6(A) is a cross-sectional view showing an annular base 51 on which a Ni-Co alloy plating layer 55 is formed. The base 51 has a surface 51a, a back surface 51b, a through hole 51c, and a protrusion 51d, which correspond to the surface 13a, back surface 13b, through hole 13c, and protrusion 13d of the base 13 of the electroformed grinding wheel 11 (see Figure 1(A)). The annular Ni-Co alloy plating layer 55 is formed on the outer circumference of the back surface 51b side of the base 51.

[0057] Figure 6(B) is a cross-sectional view showing an annular base 51 with its outer periphery etched. After a Ni-Co alloy plating layer 55 is formed on the base 51, the outer periphery of the base 51 is etched, causing the Ni-Co alloy plating layer 55 to protrude radially outward from the outer edge of the base 51. This results in a hub-type electroformed grinding wheel in which the annular Ni-Co alloy plating layer 55 formed along the outer edge of the base 51 functions as a cutting edge. This electroformed grinding wheel corresponds to the electroformed grinding wheel 11 shown in Figure 1(A).

[0058] Figure 7 is a partial cross-sectional front view showing a manufacturing apparatus 40 for producing washer-type electroformed grinding wheels. Washer-type electroformed grinding wheels can be manufactured using the same manufacturing apparatus 40 as hub-type electroformed grinding wheels.

[0059] When manufacturing a washer-type electroformed grinding wheel, a disc-shaped base 61 is immersed in the plating solution 44 instead of the base 51 (see Figure 5). A mask 63 is formed on the base 61 so as to cover it. The mask 63 has an annular opening corresponding to the shape of the grinding wheel portion 23 (see Figure 1(B)), and a part of the base 61 is exposed inside the opening of the mask 63.

[0060] When the switch 52 is turned on while the plating solution 44 is stirred by the fan 54, the base 61 functions as the cathode and the electrode 48 as the anode, and a direct current flows through the plating solution 44. As a result, a Ni-Co alloy plating layer containing abrasive grains and fluororesin is electrodeposited onto the area of ​​the base 61 that is exposed and not covered by the mask 63. Figure 8(A) is a cross-sectional view showing the disc-shaped base 61 on which the Ni-Co alloy plating layer 65 has been formed.

[0061] Subsequently, the annular Ni-Co alloy plating layer 65 is peeled off and separated from the base 61. This yields a washer-type electroformed grinding wheel that functions as a cutting edge. Figure 8(B) is a cross-sectional view showing the Ni-Co alloy plating layer 65 separated from the disc-shaped base 61. The Ni-Co alloy plating layer 65 formed in this way corresponds to the electroformed grinding wheel 21 shown in Figure 1(B).

[0062] The electroformed grinding wheels 11 and 21 shown in Figures 1(A) and 1(B) are manufactured by the above manufacturing method. The composition ratio of the binder 43 (see Figure 4) contained in the electroformed grinding wheels 11 and 21 can be controlled by the concentration of the plating solution 44 (see Figures 5 and 7). Furthermore, the content of the fluororesin 45 (see Figure 4) in the binder 43 can be controlled by the amount of fluororesin-containing solution 46 (see Figures 5 and 7) added.

[0063] Specifically, the ratio of Ni to Co contained in the plating solution 44 is reflected in the ratio of Ni to Co contained in the binder 43. In addition, the ratio of fluororesin to metal (Ni and Co) contained in the plating solution 44 is reflected in the content of fluororesin 45 in the binder 43.

[0064] The Co content and fluororesin content in the binder 43 are adjusted so that the strength of the binder 43 is maintained above a certain level, and so that spontaneous cutting edges are easily generated when the workpiece 31 is cut. Specifically, the Co content in the binder 43 is preferably 5 wt% or more and 30.2 wt% or less. Furthermore, the fluororesin content in the binder 43 is preferably 3 vol% or more and less than 40 vol%.

[0065] As described above, in the electroformed grinding wheels 11 and 21 according to this embodiment, the abrasive grains 41 are fixed by a binder 43 made of a Ni-Co alloy and containing a fluororesin 45. The binder 43, made of a Ni-Co alloy with high hardness and rigidity, maintains the strength of the electroformed grinding wheels 11 and 21, while the fluororesin 45 accelerates the shedding of the abrasive grains 41. This makes it possible to suppress the decrease in strength of the electroformed grinding wheels 11 and 21 while promoting self-sharpening, thereby preventing damage to the electroformed grinding wheels 11 and 21 and the occurrence of processing defects.

[0066] Next, the evaluation results of the electroformed grinding wheel according to this embodiment will be described. In this evaluation, an electroformed grinding wheel was manufactured in which abrasive grains were fixed by a binder made of Ni-Co alloy and containing a fluorine-based resin, and the mechanical properties of the electroformed grinding wheel and the processing quality when a workpiece was processed with the electroformed grinding wheel were evaluated.

[0067] In this evaluation, a washer-type electroformed grinding wheel (see Figure 1(B)) manufactured by electroplating (see Figure 7) was used. The dimensions of the electroformed grinding wheel were set to an outer diameter of 56 mm, an inner diameter of 40 mm, and a thickness of 0.05 mm. Granular diamond (average particle size 8 μm, concentration 45) was used as the grinding material, and granular PTFE (average particle size 0.3 μm) was used as the fluororesin.

[0068] First, nine types of electroformed grinding wheels with different Co content in the binder were manufactured. The Co content in the binder of each electroformed grinding wheel was 0 wt% (Ni plating layer), 3.1 wt%, 5 wt%, 8.1 wt%, 13.6 wt%, 20.3 wt%, 27.1 wt%, 30.2 wt%, and 35 wt%, respectively. In addition, the fluoropolymer (PTFE) content in the binder was standardized to 20 vol% for all electroformed grinding wheels.

[0069] The above Co content (wt%) corresponds to the ratio of the mass of Co in the binder to the total mass of the binder (sum of the masses of Ni and Co in the binder). The above fluororesin content (vol%) corresponds to the total volume of fluororesin in the binder to the total volume of the binder. The curvature, hardness, and rigidity were then measured for each of the nine types of electroformed grinding wheels.

[0070] Figure 9(A) is a graph showing the relationship between the Co content and the degree of warping of the electroformed grinding wheel. The degree of warping of the electroformed grinding wheel corresponds to the maximum difference in position between the center and the outer edge of the electroformed grinding wheel in the thickness direction. The greater the warping of the electroformed grinding wheel, the more likely it is to break or meander when cutting a workpiece with the electroformed grinding wheel.

[0071] As shown in Figure 9(A), using a binder containing Co (Ni-Co alloy plating layer) reduced the warping of the electroformed grinding wheel compared to using a binder without Co (Ni plating layer). In particular, when the Co content was between 5 wt% and 30.2 wt%, the magnitude of the warping of the electroformed grinding wheel was reduced to less than 1 / 3 of that when using a Ni plating layer, confirming that it is extremely effective in suppressing the warping of electroformed grinding wheels.

[0072] Figure 9(B) is a graph showing the relationship between the Co content and the hardness (Vickers hardness) of the electroformed grinding wheel. Figure 9(C) is a graph showing the relationship between the Co content and the rigidity of the electroformed grinding wheel. As shown in Figures 9(B) and 9(C), using a Ni-Co alloy plating layer improved the hardness and rigidity of the electroformed grinding wheel compared to using a Ni plating layer. In particular, when the Co content was between 8.1 wt% and 30.2 wt%, the increase in hardness was significant, confirming that it is extremely effective in improving the strength of the electroformed grinding wheel.

[0073] Next, eight types of electroformed grinding wheels were manufactured, each with a different fluoropolymer (PTFE) content in the binder. The fluoropolymer content in the binder for each electroformed grinding wheel was 0 vol% (no fluoropolymer), 5 vol%, 10 vol%, 20 vol%, 25 vol%, 30 vol%, 35 vol%, and 40 vol%, respectively. The Co content in the binder was standardized to 20 wt% for all electroformed grinding wheels. The stiffness of each of the eight types of electroformed grinding wheels was then measured.

[0074] Figure 10(A) is a graph showing the relationship between the fluororesin content and the stiffness (Vickers hardness) of the electroformed grinding wheel. As shown in Figure 10(A), when a Ni-Co alloy plating layer is used as the binder, the stiffness of the electroformed grinding wheel hardly changes even when fluororesin is included in the binder, confirming that the strength of the electroformed grinding wheel is not easily reduced by the inclusion of fluororesin. However, when the fluororesin content reached 40 vol%, the electroformed grinding wheel became brittle and broke. Therefore, it is preferable to keep the fluororesin content below 40 vol%, and more preferably below 35 vol%.

[0075] Next, we actually cut workpieces using seven types of electroformed grinding wheels with different fluororesin (PTFE) content in the binder. The fluororesin content in the binder of each electroformed grinding wheel was 0 vol% (no fluororesin), 3 vol%, 10 vol%, 20 vol%, 25 vol%, 30 vol%, and 35 vol%, respectively. The Co content in the binder was standardized to 20 wt% for all electroformed grinding wheels. After cutting the workpieces with each electroformed grinding wheel, the machining quality was evaluated by measuring the size of the chips (chips) that occurred in the workpieces.

[0076] The workpiece used was borosilicate glass measuring 100 mm in length, 100 mm in width, and 0.5 mm in thickness. A cutting device (see Figure 2) was used to cut the workpiece. The workpiece, held by a chuck table, was cut with an electroformed grinding wheel, dividing it into multiple chips.

[0077] Specifically, first, the electroformed grinding wheel was placed on the outside of the workpiece. The height of the electroformed grinding wheel was also adjusted so that its lower end was positioned below the bottom surface of the workpiece. Then, while rotating the electroformed grinding wheel (rotation speed: 15000 / min), the chuck table was moved along a direction roughly parallel to the length of the workpiece (machining feed rate: 10 mm / s), and the workpiece was cut along its length. After that, the electroformed grinding wheel was moved in 5 mm increments along the width of the workpiece, and the cutting of the workpiece was repeated using the same procedure.

[0078] Next, the chuck table was rotated 90° horizontally, and the workpiece was cut multiple times along its width under the same conditions. As a result, the workpiece was divided into multiple rectangular chips (5 mm long, 5 mm wide, and 0.5 mm thick).

[0079] Next, the underside of the divided workpiece (multiple chips) was observed, and the longest chip (maximum chip) that had progressed from the cut edge on the underside of the workpiece was identified. The length of the maximum chip was then measured and recorded as the maximum chip size. The above procedure was performed for each of the seven workpieces cut with seven different electroformed grinding wheels.

[0080] Figure 10(B) is a graph showing the relationship between the fluororesin content and the maximum chipping size. As shown in Figure 10(B), when the fluororesin content was 3 vol% or higher, the maximum chipping size was significantly reduced. In particular, when the fluororesin content was 20 vol% or higher, the reduction in the maximum chipping size was remarkable (8 μm or less), confirming that the processing quality was improved very effectively. It is presumed that this reduction in the maximum chipping size is due to the fluororesin promoting self-sharpening and maintaining the sharpness of the electroformed grinding wheel.

[0081] Based on the above evaluation results, it was confirmed that the electroformed grinding wheel according to this embodiment has high strength and is prone to spontaneous sharpening.

[0082] The structure, method, etc., according to this embodiment can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of Symbols]

[0083] 11 Electroformed grinding wheel 13 Base 13a surface 13b Back side 13c through hole 13d convex part 15. Grinding Wheel Section 21 Electroformed grinding wheel 23. Sharpening Stone Section 23a surface 23b Back side 23c through hole 31 Workpiece 41 abrasive grains 43. Bonding agent (adhesive) 45 Fluorine-based resins 51 Base 51a surface 51b back side 51c through hole 51d convex part 53 masks 55 Ni-Co alloy plating layer 61 base 63 masks 65 Ni-Co alloy plating layer 2 Cutting equipment 4 bases 6 Covers 6a front 8 cutting units 10 Housing 12 spindles 14 Mount 16 Flange section 16a surface 16b Convex part 18. Support shaft (boss section) 18a Threaded part 20 Fixing nuts 20a opening 22 Chuck table (holding table) 22a Holding surface 24 Cassette Elevator 26 cassettes 28 Display Unit (Display Device) 30 Control Unit (Control Device) 40 Manufacturing equipment 42 Plating Bathtub 44 Plating solution 46 Solution 48 electrode 50 DC power supply 52 switches 54 Fans 56 Rotary drive source

Claims

1. The grinding wheel comprises a grinding wheel portion including abrasive grains and a binder for fixing the abrasive grains, The binder is made of a Ni-Co alloy and contains a fluororesin. An electroformed grinding wheel characterized in that the Co content in the binder is 5 wt% or more and 30.2 wt% or less.

2. The electroformed grinding wheel according to claim 1, characterized in that the Co content in the binder is 8.1 wt% or more.

3. The electroformed grinding wheel according to claim 1 or 2, characterized in that the content of the fluororesin in the binder is 3 vol% or more and 35 vol% or less.

4. The average particle size of the abrasive grains is 1 μm or more and 80 μm or less. The electroformed grinding wheel according to any one of claims 1 to 3, characterized in that the average particle size of the fluororesin is 0.1 μm or more and 20 μm or less.

5. The electroformed grinding wheel according to any one of claims 1 to 4, characterized by comprising an annular base and an annular grinding wheel portion formed along the outer peripheral edge of the base.

6. The electroformed grinding wheel according to any one of claims 1 to 4, characterized in that it is composed of an annular grinding wheel portion.