grinding wheel

Abstract

To provide a grinding wheel which can properly supply a grinding fluid to a ground surface of each grind stone while preventing damage of the grind stones.SOLUTION: A grinding wheel grinds a workpiece and includes: a base; and grind stones each fixed to the base and having a grinding surface configured to contact with the workpiece. A recessed part is provided at the grinding surface side of the grind stone, and a reinforcement member which has fracture toughness lower than that of the grind stone and reinforces the grinding surface side of the grind stone is provided at the recessed part.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a grinding wheel for grinding a workpiece.

Background Art

[0002] Device chips having devices are manufactured by dividing a wafer on which a plurality of devices are formed into individual pieces. Further, a package substrate is formed by mounting a plurality of device chips on a predetermined substrate and coating and sealing the device chips with a resin layer (mold resin). By dividing this package substrate into individual pieces, a package device including a plurality of packaged device chips is manufactured. Device chips and package devices are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] In recent years, with the miniaturization of electronic devices, there has been a demand for thinning of device chips and package devices. Therefore, a process of grinding and thinning a wafer or a package substrate before division may be performed using a grinding apparatus. The grinding apparatus includes a chuck table for holding a workpiece and a grinding unit for performing grinding on the workpiece. The grinding unit includes a spindle, and an annular grinding wheel having a plurality of grinding wheels is mounted at the tip of the spindle. The workpiece is held by the chuck table, and the grinding surface of the grinding wheel is brought into contact with the workpiece while rotating the chuck table and the grinding wheel, whereby the workpiece is ground (see Patent Document 1).

[0004] When a workpiece is ground with a grinding wheel, the grinding wheel generates heat due to friction between the grinding surface of the grinding wheel and the workpiece, and the consumption of the grinding wheel is accelerated. Further, when chips (grinding chips) generated by the grinding process enter between the grinding surface of the grinding wheel and the workpiece, the grinding wheel is easily scraped by the grinding chips and consumed. Therefore, during the grinding process, a liquid such as pure water (grinding fluid) is supplied to the workpiece and the grinding wheel. Thereby, the workpiece and the grinding wheel are cooled, and the grinding chips are washed away.

[0005] However, during grinding of a workpiece, the entire grinding surface of the grinding wheel is in contact with the workpiece, making it difficult to supply grinding fluid between the grinding surface and the workpiece. Therefore, a grinding wheel has been proposed in which a recess is formed on the grinding surface side that functions as a flow path for the grinding fluid (see Patent Document 2). By forming a recess on the grinding surface side of the grinding wheel, the grinding fluid enters the recess during grinding of the workpiece, making it easier to supply grinding fluid to the grinding surface. As a result, the workpiece and the grinding wheel are efficiently cooled, and the grinding chips generated by grinding the workpiece are properly discharged. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2000-288881 [Patent Document 2] Japanese Patent Publication No. 2020-1123 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] As described above, providing recesses on the grinding surface side of the grinding wheel promotes the supply of grinding fluid to the grinding surface. However, when recesses are formed on the grinding wheel, the grinding surface side of the grinding wheel is divided into multiple protrusions (convex parts), reducing the strength of the grinding surface side of the grinding wheel. This increases the risk of the grinding surface side of the grinding wheel breaking during grinding of the workpiece, resulting in processing defects. Furthermore, depending on the extent of the damage to the grinding wheel, it may be necessary to replace the grinding wheel, leading to decreased processing efficiency and increased costs.

[0008] The present invention has been made in view of the above problems, and aims to provide a grinding wheel that can appropriately supply grinding fluid to the grinding surface of a grinding wheel while preventing damage to the grinding wheel. [Means for solving the problem]

[0009] According to one aspect of the present invention, a grinding wheel for grinding a workpiece comprises a base and a grinding wheel fixed to the base and having a grinding surface that contacts the workpiece, wherein a recess is provided on the grinding surface side of the grinding wheel, and a reinforcing member having lower fracture toughness than the grinding wheel and reinforcing the grinding surface side of the grinding wheel is provided in the recess. The grinding wheel is positioned such that the recess is aligned with the tangential direction of the rotation path of the grinding wheel. A grinding wheel is provided.

[0010] Preferably, the reinforcing member is made of resin. Preferably, the resin is a thermosetting resin. Preferably, the reinforcing member contains a filler. Preferably, the filler is silica particles or glass spheres. [Effects of the Invention]

[0011] A grinding wheel according to one aspect of the present invention comprises a grinding wheel with a recess on the grinding surface side, and the recess is provided with a reinforcing member that has lower fracture toughness than the grinding wheel and reinforces the grinding surface side of the grinding wheel. As a result, the grinding surface side of the grinding wheel with the recess is reinforced with the reinforcing member, and a flow path for grinding fluid can be formed on the grinding surface side of the grinding wheel by utilizing the wear of the reinforcing member. As a result, damage to the grinding wheel is prevented, and grinding fluid is more easily supplied to the grinding surface of the grinding wheel. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing a grinding machine. [Figure 2] This is a perspective view showing a grinding wheel. [Figure 3] This is a perspective view showing a grinding wheel. [Figure 4] This is a cross-sectional view showing a portion of a grinding wheel used to grind a workpiece. [Figure 5] This is a perspective view showing a first modified example of a grinding wheel. [Figure 6] This is a perspective view showing a second modified example of the grinding wheel. [Modes for carrying out the invention]

[0013] Hereinafter, an embodiment according to one aspect of the present invention will be described with reference to the attached drawings. First, an example of the configuration of a grinding apparatus capable of grinding a workpiece using a grinding wheel according to this embodiment will be described. Figure 1 is a perspective view showing a grinding apparatus 2 for grinding a workpiece 11. In Figure 1, the X-axis direction (first horizontal direction, front-back direction) and the Y-axis direction (second horizontal direction, left-right direction) are perpendicular to each other. Also, the Z-axis direction (height direction, vertical direction, up-down direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0014] For example, the workpiece 11 is a disc-shaped wafer made of a semiconductor material such as single-crystal silicon, and has a surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other. The workpiece 11 is divided into multiple rectangular regions by multiple streets (planned division lines) arranged in a grid pattern so as to intersect each other. Furthermore, devices (not shown) such as ICs (Integrated Circuits), LSIs (Large Scale Integrations), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed on the surface 11a side of each of the multiple regions divided by the streets.

[0015] By dividing the workpiece 11 along the street, multiple device chips, each containing a device, are manufactured. Various processing devices can be used to divide the workpiece 11, such as a cutting device that cuts the workpiece 11 with an annular cutting blade, or a laser processing device that processes the workpiece 11 by irradiating it with a laser beam. In addition, if the back surface 11b of the workpiece 11 is ground with a grinding device 2 before dividing the workpiece 11 to thin it, a thin device chip can be obtained.

[0016] However, there are no restrictions on the type, material, size, shape, structure, etc. of the workpiece 11. For example, the workpiece 11 may be a wafer (substrate) made of semiconductors other than silicon (such as GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. Also, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the devices, and the workpiece 11 may not have devices formed thereon.

[0017] The grinding device 2 includes a base 4 that supports or houses each component constituting the grinding device 2. On the upper surface side of the base 4, a rectangular opening 4a is provided whose longitudinal direction is along the X-axis direction. Also, on the upper surface side of the rear end portion of the base 4, a rectangular parallelepiped support structure 6 is provided along the Z-axis direction.

[0018] Inside the opening 4a, a chuck table (holding table) 8 for holding the workpiece 11 is provided. The upper surface of the chuck table 8 is a flat surface that is generally parallel to the horizontal plane (XY plane), and constitutes a holding surface 8a for holding the workpiece 11. The holding surface 8a 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 8.

[0019] The chuck table 8 is connected to an X-axis moving unit 10 that moves the chuck table 8 along the X-axis direction. The X-axis moving unit 10 is, for example, a ball screw type moving mechanism and is provided inside the opening 4a. Specifically, the X-axis moving unit 10 includes an X-axis ball screw (not shown) arranged along the X-axis direction and an X-axis pulse motor (not shown) that rotates the X-axis ball screw.

[0020] The X-axis movement unit 10 includes a flat table cover 12 that surrounds the chuck table 8. The front and rear of the table cover 12 are provided with bellows-shaped dustproof and waterproof covers 14 that can be extended and retracted along the X-axis direction. The table cover 12 and the dustproof and waterproof covers 14 are installed to cover the components of the X-axis movement unit 10 (X-axis ball screw, X-axis pulse motor, etc.) that are housed inside the opening 4a.

[0021] When the X-axis movement unit 10 is activated, the chuck table 8 moves along the X-axis direction together with the table cover 12 and is positioned at the front end (conveying position) or rear end (grinding position) of the opening 4a. The chuck table 8 is also connected to a rotational drive source (not shown), such as a motor, which rotates the chuck table 8 around a rotation axis that is approximately parallel to the Z-axis direction.

[0022] A Z-axis movement unit 16 is provided on the front side of the support structure 6. The Z-axis movement unit 16 comprises a pair of Z-axis guide rails 18 arranged along the Z-axis direction. A flat Z-axis movement plate 20 is mounted on the pair of Z-axis guide rails 18 so as to be slidable along the Z-axis guide rails 18.

[0023] A nut portion (not shown) is provided on the back side (rear side) of the Z-axis moving plate 20. A Z-axis ball screw 22, which is positioned along the Z-axis direction between a pair of Z-axis guide rails 18, is screwed into this nut portion. A Z-axis pulse motor 24, which rotates the Z-axis ball screw 22, is connected to the end of the Z-axis ball screw 22. When the Z-axis pulse motor 24 rotates the Z-axis ball screw 22, the Z-axis moving plate 20 moves (up and down) along the Z-axis guide rails 18 in the Z-axis direction.

[0024] A support member 26 is fixed to the front surface of the Z-axis moving plate 20. The support member 26 supports a grinding unit 28 that performs grinding on the workpiece 11. The grinding unit 28 includes a cylindrical housing 30 supported by the support member 26. The housing 30 houses a cylindrical spindle 32 arranged along the Z-axis direction. The tip (lower end) of the spindle 32 protrudes downward from the lower surface of the housing 30. A rotational drive source (not shown), such as a motor, is connected to the base (upper end) of the spindle 32.

[0025] A disc-shaped wheel mount 34 made of metal or the like is fixed to the tip of the spindle 32. An annular grinding wheel 36 for grinding the workpiece 11 is detachably mounted on the underside of the wheel mount 34. The grinding wheel 36 rotates around a rotation axis that is roughly parallel to the Z-axis direction by power transmitted from the rotation drive source via the spindle 32 and wheel mount 34. The configuration and function of the grinding wheel 36 will be described later (see Figure 2).

[0026] Furthermore, the grinding device 2 includes a control unit (control unit, control device) 38 that controls the grinding device 2. The control unit 38 is connected to each component of the grinding device 2 (chuck table 8, X-axis movement unit 10, Z-axis movement unit 16, grinding unit 28, etc.). The control unit 38 controls the operation of the grinding device 2 by outputting control signals to each component of the grinding device 2.

[0027] For example, the control unit 38 is comprised of a computer. Specifically, the control unit 38 includes a processing unit that performs calculations for operating the grinding machine 2, and a storage unit that stores various information (data, programs, etc.) used for operating the grinding machine 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).

[0028] When grinding the workpiece 11 with the grinding device 2, the workpiece 11 is first held by the chuck table 8. For example, the workpiece 11 is placed on the chuck table 8 such that its front surface 11a faces the holding surface 8a and its back surface 11b is exposed upwards. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 8a, the workpiece 11 is held by the chuck table 8. After that, the chuck table 8 is moved by the X-axis moving unit 10 and positioned below the grinding wheel 36 (grinding position).

[0029] Subsequently, while the chuck table 8 and spindle 32 are rotated in predetermined directions at predetermined speeds, the grinding wheel 36 is lowered at a predetermined speed by the Z-axis movement unit 16 and brought into contact with the workpiece 11. As a result, the back surface 11b of the workpiece 11 is removed, and the workpiece 11 is ground and thinned.

[0030] Next, an example of the configuration of the grinding wheel 36 mounted on the grinding unit 28 of the grinding device 2 will be described. Figure 2 is a perspective view showing the grinding wheel 36.

[0031] The grinding unit 28 comprises an annular base 40 and a plurality of grinding wheels 42 fixed to the base 40. For example, the grinding wheel 36 is fixed to the wheel mount 34 (see Figure 1) by fasteners such as fastening bolts (not shown). In this way, the grinding wheel 36 is mounted on the tip of the spindle 32 via the wheel mount 34.

[0032] For example, the base 40 is made of a metal such as an aluminum alloy and is formed to be approximately the same diameter as the wheel mount 34 (see Figure 1). The base 40 also has a first surface 40a and a second surface 40b that are approximately parallel to each other. The first surface 40a corresponds to a fixed end surface that is fixed to the wheel mount 34, and the second surface 40b corresponds to a free end surface that is not fixed to the wheel mount 34.

[0033] An opening 40c is provided in the center of the base 40, extending from the first surface 40a to the second surface 40b and penetrating the base 40 in the thickness direction. For example, the opening 40c is formed in the shape of a frustoconical pyramid, with its diameter increasing from the first surface 40a to the second surface 40b.

[0034] An annular groove 40d is provided on the second surface 40b of the base 40. The groove 40d is formed concentrically with the base 40, on the outer peripheral edge side of the base 40, beyond the opening 40c. Multiple grinding wheels 42 are fixed inside the groove 40d.

[0035] The grinding wheel 42 is composed of abrasive grains and a binder (bonding material) that fixes the abrasive grains. For example, a glassy vitrified bond mainly composed of SiO2 can be used as the binder. As abrasive grains, diamond, cBN (cubic boron nitride), etc., with an average particle size of 0.5 μm or more and 0.6 μm or less can be used. However, there are no restrictions on the material of the binder, the material of the abrasive grains, or the particle size of the abrasive grains.

[0036] Multiple grinding wheels 42 are formed, for example, in a rectangular parallelepiped shape and are arranged in a ring shape at roughly equal intervals along the groove 40d. The width of the grinding wheels 42 and the width of the groove 40d are roughly equal, and the grinding wheels 42 are positioned so that their length (longitudinal direction) is aligned with the tangential direction (circumferential direction) of the groove 40d. The grinding wheels 42 also have a rectangular grinding surface 42a that is exposed on the side opposite to the base 40. The grinding surface 42a is the surface that comes into contact with the workpiece 11 during grinding, and the workpiece 11 is ground by the grinding surface 42a.

[0037] Furthermore, the base 40 is provided with a plurality of grinding fluid supply passages 40e that penetrate the base 40 from the first surface 40a to the second surface 40b. One end of the grinding fluid supply passage 40e opens on the first surface 40a, and the other end of the grinding fluid supply passage 40e opens in the region between the opening 40c and the groove 40d on the second surface 40b. The multiple openings of the grinding fluid supply passages 40e exposed on the second surface 40b are arranged in a ring shape at roughly equal intervals along the circumferential direction of the base 40.

[0038] The grinding wheel 36 is mounted on a wheel mount 34 fixed to the tip of the spindle 32 (see Figure 1). When the spindle 32 is rotated in this state, the grinding wheel 36 rotates around a rotation axis that is roughly parallel to the Z-axis direction. As a result, each of the multiple grinding wheels 42 rotates (swirls) along an annular rotation path centered on the rotation axis of the grinding wheel 36. The workpiece 11 is then ground by bringing the grinding surface 42a of the rotating grinding wheels 42 into contact with the workpiece 11.

[0039] When grinding the workpiece 11 with the grinding wheel 36, a liquid such as pure water (grinding fluid) is supplied to one end of the grinding fluid supply passage 40e (the first surface 40a side of the base 40), and the grinding fluid is supplied to the workpiece 11 and the multiple grinding wheels 42 from the other end of the grinding fluid supply passage 40e. This cools the workpiece 11 and the grinding wheels 42, and washes away the debris (grinding debris) generated by grinding the workpiece 11.

[0040] However, during grinding of the workpiece 11, the entire grinding surface 42a of the grinding wheel 42 is in contact with the workpiece 11, making it difficult to supply grinding fluid to the grinding surface 42a. If the supply of grinding fluid to the grinding surface 42a is insufficient, the cooling of the grinding wheel 42 becomes inadequate. As a result, the grinding wheel 42 generates heat due to friction between the grinding surface 42a and the workpiece 11, and the grinding wheel 42 wears down quickly. In addition, grinding debris that gets trapped between the workpiece 11 and the grinding surface 42a is not properly discharged, and the grinding wheel 42 is easily worn down by being eroded by the debris.

[0041] Therefore, in this embodiment, a recess is provided on the grinding surface 42a side of the grinding wheel 42, and a reinforcing member that can reinforce the grinding surface 42a side of the grinding wheel 42 and has low fracture toughness is provided in the recess. This maintains the strength of the grinding wheel 42 and prevents damage to the grinding wheel 42, and also facilitates the supply of grinding fluid to the entire grinding surface 42a. The details of the grinding wheel 42 will be described below.

[0042] Figure 3 is a perspective view showing the grinding wheel 42. For example, the grinding wheel 42 is formed in the shape of a rectangular parallelepiped with different lengths and widths, and has a rectangular grinding surface 42a and a fixing surface 42b that are generally parallel to each other. The fixing surface 42b corresponds to a fixed end surface that is fixed inside a groove 40d (see Figure 2) provided in the base 40.

[0043] Furthermore, the grinding wheel 42 has sides 42c, 42d, 42e, and 42f that are generally perpendicular to the grinding surface 42a and the fixed surface 42b. The pair of sides 42c and 42d are arranged generally parallel to each other along the length direction (longitudinal direction) of the grinding wheel 42 and are connected to the long sides of the grinding surface 42a and the fixed surface 42b. On the other hand, the pair of sides 42e and 42f are arranged generally parallel to each other along the width direction (short direction) of the grinding wheel 42 and are connected to the short sides of the grinding surface 42a and the fixed surface 42b. However, there are no restrictions on the shape of the grinding wheel 42. For example, the grinding wheel 42 may be formed in a gentle arc shape so as to follow the groove 40d of the base 40.

[0044] The grinding surface 42a side of the grinding wheel 42 is provided with a plurality of recesses (grooves) 44 that are exposed on the grinding surface 42a. For example, the recesses 44 are formed in a straight line (strip shape) along the length direction of the grinding wheel 42 and are exposed on the side surfaces 42e and 42f. The plurality of recesses 44 are generally parallel to each other and are arranged at predetermined intervals in the width direction of the grinding wheel 42.

[0045] The depth of the recess 44 is less than the height of the grinding wheel 42 (distance from the grinding surface 42a to the fixed surface 42b). For example, the depth of the recess 44 is set to 1 mm or more, preferably 4 mm or more, and the width of the recess 44 is set to 120 μm or more. However, the number, dimensions, and spacing of the recess 44 can be appropriately set considering various processing conditions such as the material of the workpiece 11, the material of the grinding wheel 42, and the amount of grinding fluid supplied.

[0046] The recess 44 includes a pair of side walls 44a and 44b facing each other, and a bottom surface 44c connected to the lower ends of the side walls 44a and 44b. In addition, the area on the grinding surface 42a side of the grinding wheel 42 where the recess 44 is not formed constitutes a columnar grinding region (projection, convex portion) 46 that contributes to grinding the workpiece 11.

[0047] For the formation of the recess 44, a cutting device that cuts the object with an annular cutting blade is used, for example. The recess 44 is formed by rotating the cutting blade and cutting into the grinding surface 42a side of the grinding wheel 42. In this case, the width of the recess 44 is approximately the same as the width of the cutting blade. However, there are no restrictions on the method of forming the recess 44.

[0048] The grinding surface 42a side of the grinding wheel 42 is composed of alternately arranged recesses 44 and grinding areas 46, resulting in lower strength compared to a case where the recesses 44 are not formed. Therefore, in this embodiment, a reinforcing member (reinforcing layer) 48 is provided in the recesses 44 to reinforce the grinding surface 42a side of the grinding wheel 42.

[0049] The shape of the reinforcing member 48 is generally the same as the shape of the recess 44, and the reinforcing member 48 is formed to fill the recess 44 by contacting the side walls 44a, 44b and the bottom surface 44c of the recess 44. The surface of the reinforcing member 48 that is exposed on the grinding surface 42a side constitutes a contact surface 48a that comes into contact with the workpiece 11 together with the grinding surface 42a when the workpiece 11 is being ground.

[0050] By providing a reinforcing member 48 in the recess 44, the grinding area 46 is supported and reinforced by the reinforcing member 48, making it less likely for the grinding area 46 to deform (bend). As a result, the strength of the grinding surface 42a side of the grinding wheel 42 is improved, making the grinding wheel 42 less likely to break.

[0051] Furthermore, the reinforcing member 48 is made of a material with lower fracture toughness than the grinding wheel 42. Therefore, when the workpiece 11 is ground with the grinding wheel 42, the reinforcing member 48 wears out faster than the grinding area 46, and the contact surface 48a of the reinforcing member 48 is positioned further inside the grinding wheel 42 than the grinding surface 42a.

[0052] For example, the reinforcing member 48 is made of resin. In particular, it is preferable that the reinforcing member 48 is made of a thermosetting resin, because even if the reinforcing member 48 generates heat due to friction during grinding of the workpiece 11, the shape of the reinforcing member 48 is less likely to collapse. Specific examples of resins include phenolic resin and epoxy resin. After filling the recess 44 with resin, the reinforcing member 48 is formed in the recess 44 by curing the resin with heat treatment (for example, around 180°C). The reinforcing member 48 is then supported by the side walls 44a, 44b and the bottom surface 44c of the recess 44.

[0053] Furthermore, if the reinforcing member 48 is made of resin, it is preferable that the resin contains filler (aggregate). Adding filler to the resin increases the rigidity and brittleness of the resin. This makes wear more likely to occur on the contact surface 48a of the reinforcing member 48 when the workpiece 11 is ground with the grinding wheel 42. As filler, silica particles, glass spheres, etc., can be used. For example, the resin content in the reinforcing member 48 is 15 wt% to 25 wt%, and the filler content in the reinforcing member 48 is 75 wt% to 85 wt%. However, the material and content ratio of the resin and filler can be changed as appropriate.

[0054] Although the above example describes a case where the reinforcing member 48 is made of resin, there are no restrictions on the material of the reinforcing member 48 as long as its fracture toughness is lower than that of the grinding wheel 42. Furthermore, the reinforcing member 48 may be molded into a plate shape and then fixed inside the recess 44 via an adhesive or the like.

[0055] By applying adhesive to the fixing surface 42b of the grinding wheel 42 and inserting it into the groove 40d (see Figure 2) of the base 40, the grinding wheel 42 is fixed to the base 40, and a grinding wheel 36 is obtained. The grinding wheel 36 is then mounted on the wheel mount 34 (see Figure 1) of the grinding device 2 and grinds the workpiece 11.

[0056] Figure 4 is a cross-sectional view showing a portion of the grinding wheel 42 used to grind the workpiece 11. When grinding the workpiece 11 with the grinding wheel 42, the workpiece 11 is held in the chuck table 8, and the chuck table 8 and grinding wheel 36 are rotated to bring the grinding wheel 42 into contact with the workpiece 11. As a result, the grinding surfaces 42a of the multiple grinding wheels 42, which rotate along an annular rotation path, grind the back surface 11b of the workpiece 11, thereby thinning the workpiece 11. During grinding of the workpiece 11, grinding fluid is supplied to the workpiece 11 and the grinding wheel 42 from the grinding fluid supply passage 40e (see Figure 2).

[0057] As mentioned above, the reinforcing member 48 is made of a material with lower fracture toughness than the grinding wheel 42. Therefore, when the grinding surface 42a of the grinding wheel 42 and the contact surface 48a of the reinforcing member 48 come into contact with the back surface 11b of the workpiece 11, the contact surface 48a side of the reinforcing member 48 wears out faster than the grinding surface 42a side of the grinding wheel 42. As a result, a groove 50 is formed on the grinding surface 42a side of the grinding wheel 42. This groove 50 is a recess formed by the side surfaces of the leading edges of a pair of adjacent grinding regions 46 and the contact surface 48a of the reinforcing member 48, and corresponds to the gap between the workpiece 11 and the contact surface 48a of the reinforcing member 48.

[0058] The grinding fluid supplied during the grinding of the workpiece 11 flows into the groove 50 formed by the wear of the reinforcing member 48. In other words, the groove 50 functions as a channel through which the grinding fluid flows. This makes it easier for the grinding fluid to be supplied to the entire grinding surface 42a of the grinding wheel 42.

[0059] The grinding wheel 42 is fixed so that its length aligns with the tangential direction (circumferential direction) of the outer edge of the base 40 (see Figure 2). Therefore, two adjacent grinding wheels 42 are positioned so that the side surface 42e of one grinding wheel 42 faces the side surface 42f of the other grinding wheel 42. In addition, the recess 44 and reinforcing member 48 of each grinding wheel 42 are positioned along the tangential direction (circumferential direction) of the rotation path of the grinding wheel 42. This allows the grinding fluid supplied between adjacent grinding wheels 42 to be efficiently taken into the groove 50.

[0060] As described above, the grinding wheel 36 according to this embodiment includes a grinding wheel 42 with a recess 44 on the grinding surface 42a side, and the recess 44 is provided with a reinforcing member 48 that has lower fracture toughness than the grinding wheel 42 and reinforces the grinding surface 42a side of the grinding wheel 42. This allows the grinding surface 42a side of the grinding wheel 42 with the recess 44 to be reinforced by the reinforcing member 48, while utilizing the wear of the reinforcing member 48 to form a flow path for grinding fluid on the grinding surface 42a side of the grinding wheel 42. As a result, damage to the grinding wheel 42 is prevented, and grinding fluid is more easily supplied to the grinding surface 42a of the grinding wheel 42.

[0061] In the above embodiment, an example was described in which the recess 44 and the reinforcing member 48 are provided along the longitudinal direction of the grinding wheel 42 (see Figure 3), but the configuration of the recess 44 and the reinforcing member 48 is not limited thereto. Modified examples of the grinding wheel 42 are shown in Figures 5 and 6.

[0062] Figure 5 is a perspective view showing a grinding wheel 52 that corresponds to a first modified example of the grinding wheel 42. The grinding wheel 52 is formed, for example, in the shape of a rectangular parallelepiped and has a grinding surface 52a, a fixed surface 52b, and side surfaces 52c, 52d, 52e, and 52f. The grinding surface 52a, fixed surface 52b, and side surfaces 52c, 52d, 52e, and 52f correspond to the grinding surface 42a, fixed surface 42b, and side surfaces 42c, 42d, 42e, and 42f of the grinding wheel 42 (see Figure 3), respectively.

[0063] The grinding surface 52a side of the grinding wheel 52 is provided with a plurality of recesses (grooves) 54 that are exposed on the grinding surface 52a. Each recess 54 is formed in a straight line (strip shape) along the width direction (short side direction) of the grinding wheel 52 and is exposed on the side surfaces 52c and 52d. The plurality of recesses 54 are generally parallel to each other and are arranged at predetermined intervals along the length direction (long side direction) of the grinding wheel 52.

[0064] The recess 54 includes a pair of side walls 54a and 54b facing each other, and a bottom surface 54c connected to the lower ends of the side walls 54a and 54b. Furthermore, the area on the grinding surface 52a side of the grinding wheel 52 where the recess 54 is not formed constitutes a grinding area (projection, convex portion) 56 that contributes to grinding the workpiece 11. The dimensions of the recess 54 and the grinding area 56 can be set in the same way as the recess 44 and grinding area 46 of the grinding wheel 42 (see Figure 3).

[0065] A reinforcing member (reinforcing layer) 58 is provided in the recess 54 to reinforce the grinding surface 52a side of the grinding wheel 52. The reinforcing member 58 is made of a material with lower fracture toughness than the grinding wheel 52. The material, shape, function, etc. of the reinforcing member 58 are the same as those of the reinforcing member 48 provided on the grinding wheel 42 (see Figure 3).

[0066] The grinding wheel 52 is fixed so that its length is aligned with the tangential direction of the groove 40d of the base 40 (see Figure 2). As a result, the recess 54 and the reinforcing member 58 of the grinding wheel 52 are positioned along the normal direction (radial direction) of the rotation path of the grinding wheel 52.

[0067] Figure 6 is a perspective view showing a grinding wheel 60, which corresponds to a second modified example of the grinding wheel 42. The grinding wheel 60 is formed, for example, in the shape of a rectangular parallelepiped and has a grinding surface 60a, a fixed surface 60b, and side surfaces 60c, 60d, 60e, and 60f. The shapes of the grinding surface 60a, the fixed surface 60b, and the side surfaces 60c, 60d, 60e, and 60f are the same as the grinding surface 42a, the fixed surface 42b, and the side surfaces 42c, 42d, 42e, and 42f of the grinding wheel 42 (see Figure 3).

[0068] The grinding surface 60a side of the grinding wheel 60 is provided with a plurality of recesses (grooves) 62 that are exposed on the grinding surface 60a. Each recess 62 is formed in a straight line (strip shape) along the length direction (longitudinal direction) of the grinding wheel 60 and is exposed on the side surfaces 60e and 60f. The plurality of recesses 62 are generally parallel to each other and are arranged at predetermined intervals in the width direction (short direction) of the grinding wheel 60.

[0069] Furthermore, the grinding surface 60a side of the grinding wheel 60 is provided with a plurality of recesses (grooves) 64 that are exposed on the grinding surface 60a. Each recess 64 is formed in a straight line (strip shape) along the width direction (short side direction) of the grinding wheel 60 and is exposed on the side surfaces 60c and 60d. The plurality of recesses 64 are also generally parallel to each other and are arranged at predetermined intervals along the length direction (long side direction) of the grinding wheel 60.

[0070] Recess 62 includes a pair of side walls 62a and 62b facing each other, and a bottom surface 62c connected to the lower ends of side walls 62a and 62b. Recess 64 also includes a pair of side walls 64a and 64b facing each other, and a bottom surface 64c connected to the lower ends of side walls 64a and 64b. Recesses 62 and 64 are connected to each other at the intersection.

[0071] As described above, recesses 62 and 64 are formed in a grid pattern on the grinding surface 60a side of the grinding wheel 60 so as to intersect with each other. Furthermore, the area on the grinding surface 60a side of the grinding wheel 60 where recesses 62 and 64 are not formed constitutes a grinding region (projection, convex portion) 66 that contributes to grinding the workpiece 11. The dimensions of the recesses 62, 64 and the grinding region 66 can be set in the same way as the recesses 44 and grinding region 46 of the grinding wheel 42 (see Figure 3).

[0072] Reinforcement members (reinforcement layers) 68 are provided in recesses 62 and 64 to reinforce the grinding surface 60a side of the grinding wheel 60. The reinforcement members 68 are made of a material with lower fracture toughness than the grinding wheel 60. The material, shape, function, etc. of the reinforcement members 68 are the same as those of the reinforcement members 48 provided on the grinding wheel 42 (see Figure 3).

[0073] The grinding wheel 60 is fixed so that its length is aligned with the tangential direction of the groove 40d of the base 40 (see Figure 2) (see Figure 2). As a result, the recess 62 and the reinforcing member 68 formed in the recess 62 are aligned with the tangential direction (circumferential direction) of the rotation path of the grinding wheel 60, and the recess 64 and the reinforcing member 68 formed in the recess 64 are aligned with the normal direction (radial direction) of the rotation path of the grinding wheel 60.

[0074] When grinding the workpiece 11 with the grinding wheel 60, a frictional force acts on the grinding wheel 60 along its longitudinal direction. Therefore, it is preferable that the length of the grinding area 66 is greater than the width of the grinding area 66. This makes it less likely for the grinding area 66 to be damaged due to friction.

[0075] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the objectives of the present invention. [Explanation of symbols]

[0076] 11 Workpiece 11a Surface (first side) 11b Back side (2nd side) 2. Grinding device 4 base 4a aperture 6 Support structure 8. Chuck table (holding table) 8a Holding surface 10 X-axis movement unit 12 Table Covers 14 Dustproof and splashproof cover 16 Z-axis movement unit 18 Z-axis guide rail 20 Z-axis moving plate 22 Z-axis ball screw 24 Z-axis pulse motor 26 Support member 28 Grinding Unit 30 Housing 32 spindles 34 Wheel Mount 36 grinding wheels 38 Control Unit (Control Unit, Control Device) 40 bases 40a Page 1 40b 2nd side 40c aperture 40d groove 40e Grinding fluid supply channel 42 Grinding Wheels 42a Grinding surface 42b Fixed surface 42c, 42d, 42e, 42f side view 44 Recess (groove) 44a, 44b side walls 44c bottom 46 Grinding area (protrusions, convex parts) 48 Reinforcement member (reinforcement layer) 48a Contact surface 50 grooves 52 grinding wheels 52a Grinding surface 52b Fixed surface 52c,52d,52e,52f Side 54 Recess (groove) 54a,54b side wall 54c bottom 56 Grinding area (protrusions, convex parts) 58 Reinforcement member 60 grinding wheels 60a Grinding surface 60b fixed surface 60c,60d,60e,60f Side 62 Recess (groove) 62a,62b side wall 62c base 64 Recess (groove) 64a,64b side wall 64c bottom 66 Grinding area (protrusions, convex parts) 68 Reinforcement members

Claims

1. A grinding wheel for grinding a workpiece, The apparatus comprises a base and a grinding wheel fixed to the base and having a grinding surface that contacts the workpiece, A recess is provided on the grinding surface side of the grinding wheel. The recess is provided with a reinforcing member that has lower fracture toughness than the grinding wheel and reinforces the grinding surface side of the grinding wheel. The grinding wheel is characterized in that the recess is arranged along the tangential direction of the rotation path of the grinding wheel.

2. The grinding wheel according to claim 1, characterized in that the reinforcing member is made of resin.

3. The grinding wheel according to claim 2, characterized in that the resin is a thermosetting resin.

4. The grinding wheel according to claim 2 or 3, characterized in that the reinforcing member contains a filler.

5. The grinding wheel according to claim 4, characterized in that the filler is silica particles or glass spheres.

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