Dressing method for grinding wheel

Abstract

To provide a dressing method of a grinding wheel capable of suppressing remaining of machining chips adhered to the grinding wheel.SOLUTION: A method of dressing a grindstone includes a grinding step of grinding a workpiece with the grindstone while supplying a grinding liquid to the workpiece or a first region of the grindstone fixed to a base of a grinding wheel, and a dressing step of wearing the grindstone while supplying a liquid to a second region closer to the base than the first region.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for dressing a grinding wheel used for grinding a workpiece. [Background technology]

[0002] Device chips each including a device are manufactured by dividing a wafer on which a plurality of devices are formed into individual pieces. Furthermore, a package substrate is formed by mounting a plurality of device chips on a predetermined substrate and then covering and sealing the mounted device chips with a resin layer (mold resin). Package devices each including a plurality of packaged device chips are manufactured by dividing and dividing this package substrate. The 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 thinner device chips and package devices. Therefore, a process of grinding wafers and package substrates before separation into thin wafers or package substrates using a grinding device is sometimes performed. The grinding device includes a chuck table that holds the workpiece and a grinding unit that performs the grinding process on the workpiece. The grinding unit includes a spindle, the tip of which is attached with an annular grinding wheel with multiple grinding stones (grinding wheels).

[0004] A grinding wheel has an annular base and multiple grinding stones fixed to the base. The grinding stones are formed by fixing abrasive grains, such as diamond, with a bonding material. When the workpiece is held on a chuck table and the grinding surface of the grinding stone is brought into contact with the workpiece while the grinding wheel is rotated, the abrasive grains supported by the bonding material collide with the workpiece, grinding the workpiece.

[0005] When grinding a workpiece with a grinding wheel, if the abrasive grains of the grinding wheel are not adequately exposed from the binder, the grinding ability of the grinding wheel decreases, and the force (processing load) acting on the workpiece and the grinding wheel during grinding increases. This makes the workpiece more susceptible to processing defects such as chipping. Furthermore, if the grinding wheel is unevenly worn or has an irregular shape, the grinding wheel may not properly contact the workpiece, and the intended grinding process may not be achieved. Therefore, dressing is sometimes performed before, during, or after grinding the workpiece to intentionally wear down the grinding wheel and condition it.

[0006] For example, dressing of a grinding wheel is performed by bringing the grinding wheel into contact with a dressing member (dresser board) while rotating the grinding wheel (see Patent Document 1). This allows the abrasive grains of the grinding wheel to be appropriately exposed from the binder (sharpening), and also corrects the shape of the grinding surface of the grinding wheel (truing). Dressing is also sometimes performed by colliding fine particles with the grinding wheel to remove clogging of the grinding wheel (see Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-221360 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-179533 Summary of the Invention [Problem to be solved by the invention]

[0008] Dressing the grinding wheel's grinding stone involves wearing down the grinding stone and grinding the dresser board. Therefore, when dressing the grinding stone, debris (processing debris) such as broken pieces of the grinding stone and dresser board and dust is generated and scattered. Some of the processing debris remains attached to the base of the grinding wheel, the side of the grinding stone, etc.

[0009] Chips adhering to the grinding wheel may subsequently fall off when the workpiece is ground with the grinding wheel and adhere to the upper surface (grinding surface) of the workpiece held on the chuck table. In this case, the chips may get caught between the workpiece and the grinding wheel during grinding, potentially causing defects such as cracks in the workpiece. Even when the workpiece is not placed on the chuck table, chips that fall off the grinding wheel and adhere to the holding surface of the chuck table can prevent proper contact between the workpiece and the holding surface when the workpiece is subsequently held on the holding surface. Furthermore, chips that fall off the grinding wheel may unintentionally adhere to other components of the grinding device, potentially contaminating or causing malfunctions of the device. Thus, chips remaining on the grinding wheel may adversely affect the grinding process of the workpiece, the operation and maintenance of the grinding device, and other aspects of the grinding process.

[0010] The present invention has been made in view of the above problems, and has an object to provide a method for dressing a grinding wheel that can suppress the remaining machining chips adhering to the grinding wheel. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a method for dressing a grinding wheel, comprising: a grinding step in which a workpiece is ground with the grinding wheel while supplying grinding fluid to a first region of the grinding wheel fixed to the workpiece or the base of a grinding wheel; and a dressing step in which the grinding wheel is worn while supplying fluid to a second region that is closer to the base than the first region.

[0012] Preferably, in the dressing step, the grinding wheel is worn by grinding the dresser board with the grinding wheel, and at least a portion of the liquid is supplied to the contact area between the dresser board and the grinding wheel along the base. Also, preferably, the flow rate of the liquid supplied in the dressing step is greater than the flow rate of the grinding fluid supplied in the grinding step. Also, preferably, the grinding wheel dressing method further includes, after the dressing step, a cleaning step in which a cleaning liquid is supplied to the base while rotating the grinding wheel to clean the base, and in the dressing step, the grinding wheel is worn while rotating, and the rotation speed of the grinding wheel in the cleaning step is smaller than the rotation speed of the grinding wheel in the dressing step. [Effects of the Invention]

[0013] In one aspect of the method for dressing a grinding wheel, the second region to which a liquid is supplied when the grinding wheel is worn is located closer to the base of the grinding wheel than the first region to which a grinding fluid is supplied when the workpiece is ground. This allows for quick and efficient removal of chips that are generated during dressing of the grinding wheel and adhere to the grinding wheel, thereby preventing chips from remaining on the grinding wheel after dressing of the grinding wheel. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. [Figure 2] FIG. 2 is a cross-sectional view showing a chuck table. [Figure 3] 10 is a flowchart showing a method for dressing a grindstone. [Figure 4] FIG. 4 is a partial cross-sectional front view showing the grinding device in a grinding step. [Figure 5] FIG. 4 is a partial cross-sectional front view showing the grinding device in the dressing step. [Figure 6] FIG. 10 is a partial cross-sectional front view showing the grinding device in a dressing step according to a modified example. [Figure 7] FIG. 10 is a partial cross-sectional front view showing the grinding device in a cleaning step. [Figure 8] FIG. 10 is a partial cross-sectional front view showing a grinding device according to a first modified example. [Figure 9] FIG. 10 is a partial cross-sectional front view showing a grinding device according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment according to one aspect of the present invention will be described below with reference to the accompanying drawings. First, an example of the configuration of a grinding device that can be used to implement a grinding wheel dressing method according to one aspect of the present invention will be described. FIG. 1 is a perspective view showing a grinding device 2 that grinds a workpiece 11. In FIG. 1, the X-axis direction (first horizontal direction) and the Y-axis direction (second horizontal direction) are perpendicular to each other. Furthermore, the Z-axis direction (up-down direction, height direction, vertical direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0016] For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as single crystal silicon, and includes a front surface 11a and a back surface 11b that are generally parallel to each other. The workpiece 11 is divided into a plurality of rectangular regions by a plurality of streets (planned division lines) that are arranged in a grid pattern so as to intersect with each other. Devices (not shown), such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices, are formed on the front surface 11a side of each of the regions divided by the streets.

[0017] A plurality of device chips each including a device are manufactured by dividing the workpiece 11 along the streets. Furthermore, before dividing the workpiece 11, the back surface 11b side of the workpiece 11 is ground using the grinding device 2 to thin the workpiece 11, thereby obtaining thinned device chips.

[0018] However, there are no limitations on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a substrate made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass (quartz glass, borosilicate glass, etc.), ceramics, resin, metal, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of devices, and the workpiece 11 does not necessarily have to have any devices formed thereon.

[0019] The grinding device 2 includes a chuck table (holding table) 4 that holds a workpiece 11. The chuck table 4 includes a cylindrical frame (main body) 6 made of a metal such as SUS (stainless steel), glass, ceramics, resin, or the like. A cylindrical recess 6b is provided in the center of the upper surface 6a of the frame 6. A disk-shaped holding member 8 made of a porous material such as porous ceramics is fitted into the recess 6b of the frame 6. The holding member 8 includes a large number of pores that communicate from the upper surface to the lower surface of the holding member 8.

[0020] The upper surface of the holding member 8 forms a circular suction surface 8a that sucks the workpiece 11 when the workpiece 11 is held by the chuck table 4. The upper surface 6a of the frame 6 and the suction surface 8a of the holding member 8 form a holding surface 4a that holds the workpiece 11. The holding surface 4a (suction surface 8a) is connected to a suction source (not shown) such as an ejector via pores contained in the holding member 8, a flow path 6c (see FIG. 2) provided inside the frame 6, a valve (not shown), etc.

[0021] 2 is a cross-sectional view of the chuck table 4. The holding surface 4a of the chuck table 4 is formed in a conical shape with its apex at the center of the holding surface 4a and is slightly inclined relative to the radial direction of the holding surface 4a. The chuck table 4 is arranged in a slightly inclined state so that a holding area 4b, which corresponds to a part of the holding surface 4a and extends from the center to the outer periphery of the holding surface 4a, is generally parallel to the horizontal plane (XY plane). The area of ​​the workpiece 11 held in or near the holding area 4b is ground by the grinding unit 10, which will be described later.

[0022] 2, for ease of explanation, the inclination of the holding surface 4a is exaggerated, but the actual inclination of the holding surface 4a is small. For example, when the diameter of the holding surface 4a is approximately 290 mm or more and 310 mm or less, the difference in height between the center and the outer periphery of the holding surface 4a (corresponding to the height of the cone) is set to approximately 20 μm or more and 40 μm or less.

[0023] A rotation drive source (not shown), such as a motor, is connected to the chuck table 4 to rotate the chuck table 4 around the rotation axis 4c. The rotation axis 4c of the chuck table 4 is set along a direction perpendicular to the radial direction of the holding surface 4a and is slightly inclined with respect to the Z-axis direction. The rotation axis 4c intersects with the holding surface 4a so as to pass through the center (vertex) of the holding surface 4a. A tilt adjustment mechanism (not shown) may be connected to the chuck table 4 to adjust the tilt direction and tilt angle of the chuck table 4 and the rotation axis 4c.

[0024] A moving unit (not shown) that moves the chuck table 4 in the horizontal direction (XY plane direction) is connected to the chuck table 4. For example, the moving unit is configured by a ball screw type moving mechanism or a turntable.

[0025] 1, a grinding unit 10 that performs grinding on a workpiece 11 is provided above the chuck table 4. The grinding unit 10 includes a cylindrical spindle 12 that is disposed along the Z-axis direction. A rotation drive source (not shown), such as a motor, that rotates the spindle 12 is connected to the base end (upper end) of the spindle 12.

[0026] A disk-shaped wheel mount 14 made of metal or the like is fixed to the tip (lower end) of the spindle 12. A grinding wheel 16 for processing the workpiece 11 is detachably attached to the underside of the wheel mount 14. For example, the grinding wheel 16 is detachably fixed to the wheel mount 14 by a fastener such as a bolt.

[0027] The grinding wheel 16 includes an annular base 18. For example, the base 18 is an annular member made of a metal such as aluminum or stainless steel, and is formed to have roughly the same diameter as the wheel mount 14. The upper end side of the base 18 is fixed to the underside of the wheel mount 14.

[0028] A plurality of grinding wheels (grinding wheels) 20 are fixed to the lower end side of the base 18. For example, a plurality of grinding wheels 20 formed in a rectangular parallelepiped shape are arranged in a ring shape at approximately equal intervals around the periphery of the lower end side of the base 18 along the circumferential direction of the base 18. The lower surfaces of the plurality of grinding wheels 20 each form a grinding surface 20a that grinds the workpiece 11. The grinding wheels 20 include abrasive grains made of diamond, cBN (cubic boron nitride), or the like, and a bonding material (bond material) that fixes the abrasive grains, such as a metal bond, a resin bond, or a vitrified bond. However, there are no limitations on the material, shape, structure, size, etc. of the grinding wheels 20, and the number of grinding wheels 20 can be set as desired.

[0029] When a rotary drive source (not shown) connected to the spindle 12 is operated, the spindle 12, the wheel mount 14, and the grinding wheel 16 rotate around a rotation axis 10a that is generally parallel to the Z-axis direction. This causes each of the multiple grinding wheels 20 to revolve around the rotation axis 10a along a circular revolving path that is generally parallel to the horizontal plane (XY plane).

[0030] A moving unit (not shown) that moves (lifts and lowers) the grinding unit 10 along the Z-axis direction is connected to the grinding unit 10. For example, the moving unit is configured with a ball screw type moving mechanism. Specifically, the moving unit includes a ball screw arranged along the Z-axis direction, a pulse motor that rotates the ball screw, and a nut portion that is connected to the grinding unit 10 and into which the ball screw is screwed. When the moving unit moves the grinding unit 10 up and down, the grinding wheel 16 moves relative to the chuck table 4, and the holding surface 4a of the chuck table 4 and the grinding wheel 16 move toward and away from each other along the Z-axis direction.

[0031] The grinding apparatus 2 also includes a controller (control unit, control section, control device) 22 that controls the grinding apparatus 2. The controller 22 is connected to the components of the grinding apparatus 2 (the chuck table 4, the grinding unit 10, etc.), and generates control signals that control the operation of each component.

[0032] For example, the controller 22 is configured by a computer and includes a processing unit that executes processes such as calculations required for the operation of the grinding device 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the grinding device 2. The processing unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memories such as a ROM (Read Only Memory) and RAM (Random Access Memory).

[0033] When grinding the workpiece 11, the workpiece 11 is held by the chuck table 4. Then, the grinding unit 10 is lowered while rotating the chuck table 4 and the spindle 12 (grinding wheel 16). As a result, the multiple grinding wheels 20 come into contact with the workpiece 11 while rotating, and the workpiece 11 is ground and thinned by the grinding wheels 20.

[0034] Furthermore, before, during, or after grinding of the workpiece 11, dressing is performed, which is a process of intentionally wearing down the grinding stone 20 of the grinding wheel 16. Specifically, the condition of the grinding stone 20 is adjusted by wearing down the binder on the grinding surface 20a side of the grinding stone 20. For example, dressing of the grinding stone 20 is performed by bringing the grinding stone 20 into contact with a dresser board 21 while rotating it.

[0035] The dresser board 21 is a plate-like member that dresses the grinding wheel 20. For example, the dresser board 21 is formed in a circular shape similar to the workpiece 11, and has a first surface (upper surface) 21a and a second surface (lower surface) 21b that are generally parallel to each other. The first surface 21a corresponds to a contact surface that comes into contact with the grinding wheel 20, and the second surface 21b corresponds to a held surface that is held by the holding surface 4a of the chuck table 4.

[0036] The dresser board 21 includes abrasive grains made of white alundum (WA), green carborundum (GC), or the like, and a binder (bond material) for securing the abrasive grains. For example, the binder is made of a glass material such as silica (silicon dioxide, SiO2), or a resin such as phenolic resin, epoxy resin, or polyimide resin. In this case, a dresser board 21 containing a glass material or resin as its main component is obtained. However, the materials for the abrasive grains and the binder can be selected appropriately depending on the material of the grinding wheel 20, etc.

[0037] The dresser board 21 may be supported by a support member (not shown). For example, a rigid substrate, a sheet (tape), or the like capable of supporting the dresser board 21 is fixed to the second surface 21b of the dresser board 21.

[0038] When dressing the grinding wheels 20, the dresser board 21 is held by the chuck table 4. Then, the grinding unit 10 is lowered while rotating the chuck table 4 and the spindle 12 (grinding wheel 16). As a result, the multiple grinding wheels 20 come into contact with the dresser board 21 while rotating and grind the dresser board 21, causing wear on the grinding surfaces 20a of the grinding wheels 20. As a result, the abrasive grains of the grinding wheels 20 are appropriately exposed from the binder (dressing), the shapes of the grinding surfaces 20a of the multiple grinding wheels 20 are corrected (truing), and the condition of the grinding wheels 20 is adjusted.

[0039] Next, a specific example of a method for grinding the workpiece 11 and dressing the grinding wheel 20 using the grinding device 2 will be described. FIG. 3 is a flowchart showing a grinding wheel dressing method (a method for processing a workpiece). In the grinding wheel dressing method according to this embodiment, a grinding step S1 is performed in which the workpiece 11 is ground with the grinding wheel 20, and then a dressing step S2 is performed in which the grinding wheel 20 is worn. After the dressing step S2 is performed, a cleaning step S3 in which the grinding wheel 16 is cleaned may be performed as necessary. Each step will be described in detail below.

[0040] 4 is a partial cross-sectional front view showing the grinding device 2 in the grinding step S1. In the grinding step S1, the workpiece 11 is ground by the grinding wheel 20 while a grinding fluid is supplied to the workpiece 11 and the grinding wheel 20.

[0041] For simplicity, Fig. 4 shows only the cross-sectional shape of the grinding wheel 16 (the same applies to Fig. 5 and subsequent Figs.). The base 18 of the grinding wheel 16 is formed in an annular shape, and a substantially circular opening penetrating the base 18 in its central portion in the thickness direction is provided. The base 18 has an annular outer peripheral surface 18a facing radially outward of the base 18, and an annular inner peripheral surface 18b facing the center of the base 18. The inner peripheral surface 18b corresponds to the side surface (inner wall) exposed inside the opening of the base 18.

[0042] In the grinding step S1, first, the workpiece 11 is held by the chuck table 4. For example, the workpiece 11 is placed on the chuck table 4 so that the front surface 11a faces the holding surface 4a and the back surface 11b (surface to be ground) is exposed upward. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 4a, the workpiece 11 is sucked and held by the chuck table 4. Note that a protective sheet for protecting the workpiece 11 may be attached to the front surface 11a side of the workpiece 11.

[0043] Next, the positional relationship between the chuck table 4 and the grinding wheel 16 is adjusted. Specifically, the chuck table 4 is positioned below the grinding wheel 16 so that the center of the workpiece 11 and the rotation path of the grinding wheel 20 overlap in the Z-axis direction. The chuck table 4 is then rotated around the rotation axis 4c, and the grinding wheel 16 is rotated around the rotation axis 10a. For example, the rotation speed of the chuck table 4 is 100 rpm or more and 900 rpm or less, and the rotation speed of the grinding wheel 16 (the rotation speed of the spindle 12) is 1000 rpm or more and 7000 rpm or less.

[0044] Then, while rotating the chuck table 4 and the grinding wheel 16, the grinding wheel 16 is lowered along the Z-axis direction. As a result, the chuck table 4 and the grinding wheel 16 move relatively along a direction parallel to the rotation axis 10a (Z-axis direction), and the grinding wheel 20 approaches and contacts the workpiece 11 while rotating (processing feed). The relative movement speed of the chuck table 4 and the grinding wheel 16 in the Z-axis direction at this time corresponds to the processing feed speed. The processing feed speed is, for example, not less than 0.1 μm / s and not more than 10 μm / s.

[0045] When the grinding surface 20a of the grinding wheel 20 comes into contact with the back surface 11b of the workpiece 11, the grinding wheel 20 rotates so as to pass through the rotation axis of the chuck table 4, and grinds the entire back surface 11b side of the workpiece 11. As a result, the back surface 11b side of the workpiece 11 is scraped off, and the workpiece 11 is ground and thinned.

[0046] During grinding of the workpiece 11, a liquid (grinding fluid) is supplied to the workpiece 11 and the grinding wheel 20. For example, the grinding device 2 includes a supply unit 24 that supplies the grinding fluid 32.

[0047] The supply unit 24 includes a columnar support part 26 and a nozzle 30 connected to the support part 26 via a rotation mechanism 28. For example, the support part 26 is a cylindrical member that supports the rotation mechanism 28 and the nozzle 30, and is disposed adjacent to the chuck table 4 along the Z-axis direction. The rotation mechanism 28, which is constituted by a rotation actuator or the like, is attached to the upper end of the support part 26, and the nozzle 30 that supplies the grinding fluid 32 is attached to the rotation mechanism 28.

[0048] The nozzle 30 is provided to extend from the upper end (rotation mechanism 28) of the support part 26 toward the chuck table 4, and is positioned above the holding surface 4a of the chuck table 4. For example, the nozzle 30 is disposed at a position overlapping with the inside of the rotational path of the grinding wheel 20, and supplies the grinding fluid 32 from the inside to the outside of the grinding wheel 16.

[0049] The nozzle 30 has a supply port 30a at its tip for supplying the grinding fluid 32. A grinding fluid supply source (not shown) for supplying the grinding fluid 32 to the nozzle 30 is connected to the nozzle 30 via a valve (not shown) or the like. The grinding fluid 32 may be a liquid such as pure water, or a mixed fluid obtained by mixing a liquid (such as pure water) with a gas (such as air). When the grinding fluid 32 is supplied from the grinding fluid supply source to the nozzle 30, the grinding fluid 32 is supplied from the supply port 30a of the nozzle 30 onto the holding surface 4a of the chuck table 4.

[0050] Furthermore, the rotation mechanism 28 adjusts the orientation of the nozzle 30. Specifically, when a control signal is output from the controller 22 (see FIG. 1) to the rotation mechanism 28, the rotation mechanism 28 is activated and the nozzle 30 rotates around a rotation axis that is roughly parallel to the Y-axis direction. This adjusts the angle of the nozzle 30 relative to the support part 26 (the angle relative to the Z-axis direction), allowing the direction in which the supply port 30a of the nozzle 30 faces to be set as desired. However, the type, structure, etc. of the mechanism that changes the orientation of the nozzle 30 can be freely selected. Alternatively, the orientation of the nozzle 30 may be adjusted manually by an operator.

[0051] In the grinding step S1, a grinding fluid 32 is supplied from the nozzle 30 to the workpiece 11 and the grinding wheel 20. Specifically, the orientation of the nozzle 30 is set so that the grinding fluid 32 is supplied to a first region 34 including a predetermined region of the workpiece 11 and / or a predetermined region of the grinding wheel 16. That is, the first region 34 corresponds to a region to which the grinding fluid 32 sprayed from the nozzle 30 is directly supplied. For example, the first region 34 may be a region where the workpiece 11 and the grinding wheel 20 come into contact with each other (the processing point), a region of the back surface 11b of the workpiece 11 near the processing point, or the lower end of the grinding wheel 20. Then, during grinding of the workpiece 11, the grinding fluid 32 is sprayed from the nozzle 30 to the first region 34 at a predetermined flow rate. As a result, the grinding fluid 32 is supplied directly to the processing point or indirectly via the workpiece 11 or the grinding wheel 20.

[0052] The supply of grinding fluid 32 cools the workpiece 11 and the grinding wheel 20 while the workpiece 11 is being ground. In addition, chips (machining chips) generated when the workpiece 11 is ground with the grinding wheel 20 are washed away by the grinding fluid 32. The flow rate of the grinding fluid 32 is set appropriately depending on the material of the workpiece 11 and the grinding conditions, and is, for example, 1 L / min or more and 1.5 L / min or less.

[0053] Then, grinding continues until the workpiece 11 reaches a predetermined thickness, and then the grinding unit 10 rises and the grinding wheel 20 moves away from the workpiece 11. This stops the grinding of the workpiece 11 by the grinding wheel 20, and the grinding step S1 is completed.

[0054] Next, the grinding wheel 20 is dressed (dressing step S2). Fig. 5 is a partial cross-sectional front view showing the grinding apparatus 2 in the dressing step S2. In the dressing step S2, the grinding wheel 20 is worn by grinding the dresser board 21 with the grinding wheel 20.

[0055] Specifically, first, the dresser board 21 is held by the chuck table 4. After the workpiece 11 is transferred from the chuck table 4, the dresser board 21 may be held by that chuck table 4, or may be held by a chuck table 4 different from the chuck table 4 that holds the workpiece 11.

[0056] The dresser board 21 is placed on the chuck table 4 so that the first surface 21a is exposed upward and the second surface 21b faces the holding surface 4a. In this state, when a suction force (negative pressure) from a suction source is applied to the holding surface 4a, the dresser board 21 is sucked and held by the chuck table 4. As described above, a support member may be fixed to the second surface 21b side of the dresser board 21.

[0057] Next, the positional relationship between the chuck table 4 and the grinding wheel 16 is adjusted. Specifically, the chuck table 4 is positioned below the grinding wheel 16 so that the center of the dresser board 21 and the rotation path of the grinding wheel 20 overlap in the Z-axis direction. Then, while the chuck table 4 is rotated around the rotation axis 4c and the grinding wheel 16 is rotated around the rotation axis 10a, the grinding wheel 16 is lowered along the Z-axis direction to bring the grinding wheel 20 into contact with the first surface 21a of the dresser board 21. The rotation speed of the chuck table 4, the rotation speed of the grinding wheel 16, and the processing feed rate can be set, for example, in the same way as in the grinding step S1.

[0058] When the grinding wheel 20 comes into contact with the dresser board 21, the grinding wheel 20 rotates so as to pass through the rotation axis of the chuck table 4, grinding the entire first surface 21a side of the dresser board 21. At this time, the binder of the grinding wheel 20 collides with the abrasive grains contained in the dresser board 21, accelerating wear on the grinding surface 20a side of the grinding wheel 20. As a result, the abrasive grains contained in the grinding wheel 20 are appropriately exposed from the binder (sharpening). Furthermore, the grinding surface 20a of the grinding wheel 20 is shaped flat, and the height positions of the grinding surfaces 20a of the multiple grinding wheels 20 are made uniform (truing). This adjusts the condition of the grinding wheel 20. Then, when the grinding amount of the dresser board 21 reaches a predetermined value, the descent of the grinding unit 10 (grinding feed) is stopped, and the dressing step S2 is completed.

[0059] During dressing of the grinding wheel 20, a liquid 36 is supplied to the dresser board 21 and the grinding wheel 20, thereby cooling the workpiece 11 and the grinding wheel 20. In this embodiment, as an example, a case will be described in which the grinding fluid 32 supplied from the nozzle 30 is also used as the liquid 36. However, the liquid 36 may be a liquid different from the grinding fluid 32, or may be a liquid supplied from a source other than the nozzle 30.

[0060] When the dresser board 21 is ground with the grindstone 20, chips and dust from the dresser board 21 and grindstone 20 fly around as processing debris, some of which adhere to the base 18 of the grinding wheel 16 and the upper end of the grindstone 20. If the processing debris adhering to the grinding wheel 16 falls and adheres to the holding surface 4a of the chuck table 4 or the workpiece 11 to be ground in a subsequent process, this could cause problems in holding and processing the workpiece 11.

[0061] In particular, when dressing the grinding wheel 20, the grinding wheel 20 is intentionally worn, so chips are more likely to be generated than when the workpiece 11 is processed. Furthermore, the chips generated during dressing contain hard abrasive grains contained in the dresser board 21 and dressing particles 54 (see FIG. 9 ), which will be described later, and are therefore likely to be larger in size and greater in quantity than the chips generated when the workpiece 11 is processed. If such chips adhere to the base 18 of the grinding wheel 16 or its surroundings, they are likely to have a negative impact on the subsequent processing of the workpiece 11.

[0062] Therefore, in the dressing step S2, the grinding wheel 20 is worn while supplying the liquid 36 to the second region 38, which is closer to the base 18 than the first region 34 to which the grinding fluid 32 was supplied in the grinding step S1. As a result, the liquid 36 removes the machining debris adhering to the grinding wheel 16, making it less likely that the debris will remain on the grinding wheel 16.

[0063] Specifically, in the dressing step S2, the rotation mechanism 28 is operated to set the orientation of the nozzle 30 so that the liquid 36 (grinding fluid 32) is supplied to a second region 38 that is closer to the base 18 than the first region 34. That is, the second region 38 corresponds to a region to which the liquid 36 sprayed from the nozzle 30 is directly supplied in the dressing step S2. For example, the lower surface of the wheel mount 14, the base 18, and the connection region between the base 18 and the grinding wheel 20 are set as the second region 38. FIG. 5 illustrates, as an example, a case where the inner circumferential surface 18b of the base 18 is set as the second region 38. The liquid 36 is then directly supplied to the second region 38 from the supply port 30a of the nozzle 30.

[0064] When the nozzle 30 is oriented as described above, more liquid 36 is supplied to the base 18 side of the grinding wheel 16 than when it is supplied toward the first region 34. As a result, not only the machining chips present in the vicinity of the contact area (machining point) between the dresser board 21 and the grinding wheel 20, but also the machining chips adhering to the upper end of the grinding wheel 20 and the base 18 are washed away by the liquid 36. This allows the machining chips adhering to the grinding wheel 16 during dressing of the grinding wheel 20 to be quickly removed, making it less likely that they will remain adhered to the grinding wheel 16.

[0065] At least a portion of the liquid 36 supplied to the second region 38 also functions as a grinding fluid. Specifically, the liquid 36 supplied to the second region 38 flows along the base 18 and / or the grinding wheel 20, washing away machining debris while being supplied to the contact region between the dresser board 21 and the grinding wheel 20. This cools the dresser board 21 and the grinding wheel 20.

[0066] The flow rate of the liquid 36 is appropriately set so as to properly remove chips adhering to the grinding wheel 16 and cool the dresser board 21 and the grindstone 20. For example, the flow rate of the liquid 36 may be the same as the flow rate of the grinding fluid 32 (see FIG. 4) in the grinding step S1, or may be greater than the flow rate of the grinding fluid 32 in the grinding step S1.

[0067] The method of supplying the liquid 36 to the second region 38 is not limited to adjusting the angle of the nozzle 30. For example, the support part 26 may be connected to an elevation mechanism (not shown), such as a linear actuator, that moves (lifts and lowers) the support part 26 along the Z-axis direction. In this case, the height position (position in the Z-axis direction) of the nozzle 30 is adjusted by raising and lowering the support part 26 with the elevation mechanism. Then, by positioning the supply port 30a of the nozzle 30 above the grinding step S1 (at a position closer to the base 18 of the grinding wheel 16), the liquid 36 can be supplied to the second region 38.

[0068] Furthermore, a movement mechanism (not shown) that moves the support part 26 in the horizontal direction (XY plane direction) may be connected to the support part 26. In this case, by moving the support part 26 with the movement mechanism, the supply port 30a of the nozzle 30 can be brought closer to the second region 38 of the grinding wheel 16. This makes it easier to supply the liquid 36 to the second region 38.

[0069] Furthermore, in the dressing step S2, the liquid 36 may be supplied to the first region 34 and the second region 38. Fig. 6 is a partial cross-sectional front view showing the grinding apparatus 2 in the dressing step S2 according to a modified example.

[0070] For example, the flow rate of the liquid 36 supplied in the dressing step S2 is set to be greater than the flow rate of the grinding fluid 32 supplied in the grinding step S1. In this case, the liquid 36 sprayed from the supply port 30a of the nozzle 30 spreads over a wide area, expanding the range to which the liquid 36 is supplied. This allows the liquid 36 to be supplied to the second region 38 in addition to the first region 34.

[0071] The specific flow rate of the liquid 36 is set appropriately so that the supply destination of the liquid 36 is expanded to a desired range. For example, the flow rate of the liquid 36 in the dressing step S2 is at least twice, preferably at least three times, and more preferably at least four times the flow rate of the grinding fluid 32 in the grinding step S1. An example of the flow rate of the liquid 36 is 3.5 L / min to 4 L / min. Furthermore, the supply range of the liquid 36 sprayed from the supply port 30a of the nozzle 30 can be adjusted by changing the area and structure of the supply port 30a.

[0072] As described above, in the dressing step S2, the liquid 36 is supplied to the second region 38, which is closer to the base 18 of the grinding wheel 16 than the first region 34, so that grinding of the dresser board 21 and cleaning of the grinding wheel 16 are carried out simultaneously. As a result, even if chips generated during dressing of the grinding wheel 20 adhere to the grinding wheel 16, the chips are quickly removed from the grinding wheel 16 by the liquid 36, making it difficult for the chips to adhere to and remain on the grinding wheel 16.

[0073] The liquid 36 may be continuously supplied to the second region 38 from the start to the end of dressing of the grinding wheel 20 (grinding of the dresser board 21), or may be supplied to the second region 38 only for part of the period during which the grinding wheel 20 is dressed. However, in order to prevent new machining debris from being generated and adhering to the grinding wheel 16 after the supply of the liquid 36 to the second region 38 is stopped, it is preferable that the liquid 36 be supplied to the second region 38 at least until the end of dressing of the grinding wheel 20. For example, the liquid 36 may be supplied to the first region 34 for a predetermined period from the start of dressing of the grinding wheel 20, and then the liquid 36 may be supplied to the second region 38 until the end of dressing of the grinding wheel 20.

[0074] The dressing step S2 removes most of the machining debris adhering to the grinding wheel 16. However, depending on the amount of machining debris and the amount of liquid 36 supplied, some of the machining debris adhering to the grinding wheel 16 may remain after dressing of the grinding wheel 20 is completed. Therefore, after performing the dressing step S2, a cleaning step S3 may be performed, as necessary, to clean the grinding wheel 16.

[0075] 7 is a partial cross-sectional front view showing the grinding device 2 in the cleaning step S3. In the cleaning step S3, the grinding wheel 16 is cleaned by supplying a liquid (cleaning liquid) to the grinding wheel 16 while rotating the grinding wheel 16.

[0076] Specifically, after dressing of the grinding wheel 20 is completed, the grinding unit 10 rises and the grinding wheel 20 moves away from the dresser board 21. Then, while the grinding wheel 16 continues to rotate, a cleaning liquid 40 is supplied to the grinding wheel 16. As an example, the present embodiment will describe a case where the grinding liquid 32 (liquid 36) supplied from the nozzle 30 is also used as the cleaning liquid 40. However, the cleaning liquid 40 may be a liquid different from the grinding liquid 32 and the liquid 36, or may be a liquid supplied from a source other than the nozzle 30.

[0077] After the grinding wheel 20 is separated from the dresser board 21, the upward movement of the grinding unit 10 is temporarily stopped. Then, the cleaning liquid 40 is supplied from the supply port 30a of the nozzle 30 to a predetermined area of ​​the grinding wheel 16. For example, the angle and position of the nozzle 30, the flow rate of the cleaning liquid 40, etc. are adjusted so that the cleaning liquid 40 is supplied directly from the supply port 30a of the nozzle 30 to the inner circumferential surface 18b of the base 18. As a result, the cleaning liquid 40 is supplied around the entire inner circumferential surface 18b of the base 18 and is also supplied along the base 18 to the multiple grinding wheels 20. As a result, the cleaning liquid 40 removes machining debris adhering to the base 18 and the grinding wheels 20.

[0078] However, the destination of the supply of the cleaning liquid 40 is not limited to the base 18 of the grinding wheel 16. For example, if multiple grinding wheels 20 need to be cleaned intensively, the cleaning liquid 40 may be supplied directly to the grinding wheels 20 from the nozzle 30. In this case, the multiple grinding wheels 20 are cleaned in sequence by the cleaning liquid 40 as the grinding wheel 16 rotates. Furthermore, the cleaning liquid 40 may be supplied to a location other than the grinding wheel 16. For example, the cleaning liquid 40 may be supplied to the underside of the wheel mount 14 and flow along the base 18 and the grinding wheels 20 to remove processing debris.

[0079] The rotation speed of the grinding wheel 16 (the rotation speed of the spindle 12) in the cleaning step S3 can be set appropriately so that machining debris adhering to the grinding wheel 16 is properly cleaned. However, if the rotation speed of the grinding wheel 16 is reduced, the cleaning liquid 40 supplied to the grinding wheel 16 is less likely to be repelled, which makes it easier to contribute to the removal of the machining liquid. Therefore, it is preferable that the rotation speed of the grinding wheel 16 in the cleaning step S3 be lower than the rotation speed of the grinding wheel 16 in the dressing step S2.

[0080] For example, the rotation speed of the grinding wheel 16 in the cleaning step S3 is set to 1 / 2 or less, preferably 1 / 3 or less, more preferably 1 / 10 or less, and even more preferably 1 / 100 or less of the rotation speed of the grinding wheel 16 in the dressing step S2. A specific rotation speed of the grinding wheel 16 in the cleaning step S3 is, for example, 3000 rpm or less, preferably 1000 rpm or less, more preferably 100 rpm or less, and even more preferably 60 rpm or less.

[0081] Furthermore, the time for supplying the cleaning liquid 40 to the grinding wheel 16 in the cleaning step S3 is also set appropriately depending on the expected size of the machining debris, the amount of adhesion, etc. For example, the time for supplying the cleaning liquid 40 to the grinding wheel 16 can be set to 1 minute or less, 30 seconds or less, or 15 seconds or less.

[0082] It should be noted that the rotation speed of the grinding wheel 16 does not need to be maintained at a strictly constant value while the cleaning liquid 40 is being supplied to the grinding wheel 16, but may be maintained within a predetermined range. For example, the rotation speed of the grinding wheel 16 in the cleaning step S3 is controlled so that the minimum value is 90% or more, preferably 95% or more, of the maximum value.

[0083] The flow rate of the liquid 36 can be set in the same manner as in the grinding step S1 or the dressing step S2. However, the specific value of the flow rate of the liquid 36 can be adjusted as appropriate depending on the rotation speed of the grinding wheel 16, the amount and size of machining chips expected to adhere to the grinding wheel 16, etc. Also, the supply range of the liquid 36 may be adjusted so that the liquid 36 is supplied directly to both the base 18 and the grinding wheel 20 (see FIG. 6).

[0084] The cleaning step S3 can also be performed after the descent (grinding feed) of the grinding unit 10 is stopped in the dressing step S2 and before the grinding unit 10 is raised. In this case, although the cleaning liquid 40 is supplied to the grinding wheel 16 while the grinding wheel 20 is in contact with the dresser board 21, new machining chips are unlikely to be generated because the grinding feed is stopped. However, in order to clean the grinding wheel 16 while reliably avoiding the generation of new machining chips in the cleaning step S3, it is preferable to supply the cleaning liquid 40 to the grinding wheel 16 while the grinding wheel 20 is separated from the dresser board 21 (see FIG. 7).

[0085] As described above, by performing the grinding step S1 to the cleaning step S3 in order, the grinding wheel 16 can be efficiently cleaned while dressing the grinding wheel 20 used to grind the workpiece 11 and adjusting the condition of the grinding wheel 20. Note that in this embodiment, a case has been described in which the grinding wheel 20 is dressed and the grinding wheel 16 is cleaned (dressing step S2 and cleaning step S3) after the workpiece 11 is ground (grinding step S1), but the grinding step S1 may be performed after the dressing step S2 and cleaning step S3. Furthermore, each of the grinding step S1 to cleaning step S3 may be performed multiple times.

[0086] As described above, in the grinding wheel dressing method according to this embodiment, the second region 38, to which the liquid 36 is supplied when the grinding wheel 20 is worn, is set closer to the base 18 of the grinding wheel 16 than the first region 34, to which the grinding fluid 32 is supplied when the workpiece 11 is ground. This allows for quick and efficient removal of chips that are generated during dressing of the grinding wheel 20 and adhere to the grinding wheel 16, and prevents chips from remaining on the grinding wheel 16 after dressing of the grinding wheel 20.

[0087] In the above embodiment, the grinding device 2 is described in which the grinding fluid 32 (liquid 36, cleaning fluid 40) is supplied from the nozzle 30 provided at a position overlapping the grinding wheel 16 (see FIGS. 4 to 7). However, the means for supplying the grinding fluid 32, the liquid 36, and the cleaning fluid 40 is not limited to the nozzle 30.

[0088] 8 is a partial cross-sectional front view showing a grinding apparatus 2A corresponding to a first modified example of the grinding apparatus 2. The configuration and functions of the grinding apparatus 2A are the same as those of the grinding apparatus 2, except for the points described below.

[0089] The grinding apparatus 2A includes a supply unit 24A instead of the supply unit 24 (see FIG. 4, etc.) of the grinding apparatus 2. The supply unit 24A includes a support portion 26A, a rotation mechanism 28A, and a nozzle 30A. The configurations and functions of the support portion 26A, the rotation mechanism 28A, and the nozzle 30A are similar to those of the support portion 26, the rotation mechanism 28, and the nozzle 30 of the supply unit 24, respectively.

[0090] However, the supply unit 24A is installed outside the grinding wheel 16. Specifically, the support part 26A is disposed radially outward of the grinding wheel 16 and adjacent to the chuck table 4. Furthermore, the nozzle 30A is disposed radially outward of the grinding wheel 16 and facing the grinding wheel 16, and supplies the grinding fluid 32 (liquid 36, cleaning fluid 40) toward the holding surface 4a of the chuck table 4 or the grinding wheel 16. Furthermore, the support part 26A, the rotation mechanism 28A, and the nozzle 30A do not overlap with the grinding wheel 16 in the Z-axis direction when the grinding wheel 16 grinds the workpiece 11 or the dresser board 21.

[0091] In the grinding step S1, a grinding fluid 32 is supplied to the workpiece 11 and the grinding wheel 20 from a nozzle 30A provided on the outside of the grinding wheel 16. In addition, in the dressing step S2 and the cleaning step S3, a liquid 36 or a cleaning fluid 40 is supplied from the nozzle 30A to the outer peripheral surface side of the grinding wheel 16 (for example, the outer peripheral surface 18a of the base 18). This allows for intensive removal of processing debris adhering to the outer peripheral surface side of the grinding wheel 16.

[0092] The grinding device 2A may include both a supply unit 24 (see FIG. 4, etc.) provided inside the grinding wheel 16 and a supply unit 24A provided outside the grinding wheel 16. In this case, the grinding fluid 32 (liquid 36, cleaning fluid 40) can be supplied from both the inside and outside of the grinding wheel 16.

[0093] In the above embodiment, the grinding wheel 20 is dressed by grinding the dresser board 21 with the grinding wheel 20 of the grinding wheel 16 (see FIGS. 5 and 6). However, the method of dressing the grinding wheel 20 is not limited to grinding the dresser board 21. For example, in the dressing step S2, the grinding wheel 20 can also be dressed by spraying particles or a fluid onto the grinding wheel 20 or by irradiating it with a laser beam.

[0094] 9 is a partial cross-sectional front view showing a grinding apparatus 2B corresponding to a second modified example of the grinding apparatus 2. The configuration and functions of the grinding apparatus 2B are the same as those of the grinding apparatus 2, except for the points described below.

[0095] The grinding apparatus 2B includes a dressing unit 50 that dresses the grinding wheel 20. For example, the dressing unit 50 includes an injector 52 that injects particles 54 for dressing the grinding wheel 20 together with a fluid.

[0096] The particles 54 may be, for example, abrasive grains made of aluminum oxide (Al2O3), silicon carbide (SiC), or the like, resin microparticles made of plastic such as nylon (polyamide), or water-soluble microparticles made of baking soda (sodium bicarbonate), ice particles, or the like. The average particle size of the particles 54 is selected depending on the material of the grinding wheel 20, and is, for example, 5 μm or more and 100 μm or less. The fluid to be sprayed together with the particles 54 may be a liquid such as pressurized water (high-pressure water), a gas such as pressurized air (high-pressure air), a mixture of these liquids and gases, or the like.

[0097] When the grinding step S1 (see FIG. 4) is completed, the grinding unit 10 is raised and the grinding wheel 20 is moved away from the workpiece 11. The injector 52 is positioned directly below the rotation path of the grinding wheel 20 (at a position overlapping the rotation path in the Z-axis direction). The angle and position of the nozzle 30, the flow rate of the liquid 36, etc. are adjusted so that the liquid 36 is supplied to the second region 38 of the grinding wheel 16.

[0098] Then, in the dressing step S2, particles 54 are sprayed from the injector 52 together with the fluid onto the grinding surface 20a of the grinding wheel 20 while the grinding wheel 16 continues to rotate. This causes the particles 54 to collide sequentially with the grinding surfaces 20a of the multiple grinding wheels 20. As a result, the binder of the grinding wheels 20 is worn away, and processing chips adhering to the grinding surface 20a of the grinding wheels 20 are removed, thereby dressing the grinding wheels 20.

[0099] Furthermore, in the dressing step S2, the liquid 36 is supplied from the nozzle 30 to the second region 38. As a result, even if processing debris (fragments of the grinding wheel 20, dust, particles 54, etc.) generated by dressing the grinding wheel 20 adheres to the grinding wheel 16, the liquid 36 quickly washes the processing debris away from the grinding wheel 16.

[0100] As described above, in the dressing step S2, the grinding wheel 20 can also be dressed by a method other than grinding the dresser board 21. The injector 52 may dress the grinding wheel 20 by injecting a fluid such as high-pressure water or high-pressure air onto the grinding surface 20a of the grinding wheel 20, rather than injecting particles 54. The dressing unit 50 may also be equipped with a laser irradiation unit that irradiates a laser beam, instead of the injector 52. In this case, the grinding wheel 20 can be dressed by irradiating the grinding surface 20a side of the grinding wheel 20 with a laser beam from the laser irradiation unit.

[0101] In addition, the structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0102] 11 Workpiece 11a surface 11b Back side 21 Dresser Board 21a 1st side (top side) 21b 2nd side (bottom side) 2 Grinding equipment 4 Chuck table (holding table) 4a Holding surface 4b Holding area 4c Rotation axis 6 Frame (main body) 6a Top side 6b Recess 6c Flow path 8 Retaining member 8a Suction surface 10 Grinding unit 10a Rotation axis 12 spindles 14 Wheel mount 16 Grinding Wheel 18 Foundation 18a Outer surface 18b Inner surface 20 Grinding wheel 20a grinding surface 22 Controller (control unit, control unit, control device) 24,24A supply unit 26,26A Support part 28,28A Rotation mechanism 30,30A nozzle 30a Supply port 32 Grinding fluid 34 First area 36 liquid 38 Second area 40 Cleaning Solution 50 Dress Unit 52 Injector 54 particles

Claims

1. A method for dressing a grinding wheel, comprising: a grinding step of grinding the workpiece with the grinding wheel while supplying a grinding fluid to a first region of the grinding wheel fixed to the workpiece or a base of the grinding wheel; a dressing step of abrading the grinding wheel while supplying a liquid to a second region that is closer to the base than the first region.

2. In the dressing step, the grinding wheel is worn by grinding the dresser board with the grinding wheel; 2. The method for dressing a grinding wheel according to claim 1, wherein at least a portion of the liquid is supplied to the contact area between the dresser board and the grinding wheel through the base.

3. 3. The method for dressing a grinding wheel according to claim 1, wherein the flow rate of the liquid supplied in the dressing step is greater than the flow rate of the grinding liquid supplied in the grinding step.

4. a cleaning step of supplying a cleaning liquid to the base while rotating the grinding wheel to clean the base after the dressing step; In the dressing step, the grinding stone is worn while rotating the grinding wheel; 3. The method for dressing a grinding wheel according to claim 1, wherein the rotation speed of the grinding wheel in the cleaning step is smaller than the rotation speed of the grinding wheel in the dressing step.

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