JP7547019B2 - Method for grinding a workpiece - Google Patents

Description

The present invention relates to a method for grinding a workpiece using a grinding device.

In the device chip manufacturing process, a wafer is used in which devices are formed in multiple areas partitioned by multiple intersecting streets (planned division lines). By dividing this wafer along the streets, multiple device chips, each equipped with a device, are obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

In recent years, with the miniaturization of electronic devices, there is a demand for device chips to be made thinner as well. Therefore, before dividing the wafer, a process of grinding the wafer to thin it using a grinding device is sometimes carried out. The grinding device includes a chuck table having a holding surface for holding the workpiece, and a grinding unit for grinding the workpiece, and a grinding wheel including a grinding stone is attached to the grinding unit. The grinding unit then rotates the grinding wheel to bring the grinding stone into contact with the workpiece, thereby grinding the workpiece.

When grinding a workpiece such as a wafer using a grinding device, the relative positions of the chuck table and grinding unit are adjusted so that the center of the workpiece held by the chuck table overlaps with the trajectory of the grinding wheel. Then, while the chuck table and grinding wheel are both rotating, the grinding wheel is lowered toward the holding surface of the chuck table, causing the bottom surface of the grinding wheel to come into contact with the top surface of the workpiece, grinding the workpiece. This type of grinding method is called in-feed grinding.

On the other hand, a grinding method called creep feed grinding is sometimes used to grind the workpiece. In creep feed grinding, the positional relationship between the chuck table and the grinding unit is adjusted so that the grinding wheel is positioned outside the workpiece and the bottom surface of the grinding wheel is positioned below the top surface of the workpiece. Then, without rotating the chuck table and while rotating the grinding wheel, the chuck table is moved in a direction parallel to the holding surface (horizontal direction) so that the side and bottom surfaces of the grinding wheel come into contact with the top surface of the workpiece, grinding the workpiece (see Patent Document 1).

JP 2005-28550 A

The grinding stones contained in grinding wheels are formed by fixing abrasive grains made of diamonds and the like with a bonding material. The abrasive grains protruding from the bonding material of the grinding stone collide with the workpiece, thereby grinding the workpiece. Furthermore, as grinding of the workpiece with the grinding stone continues, the bonding material wears away, causing the exposed abrasive grains to fall off and new abrasive grains embedded inside the bonding material to become exposed. This phenomenon is called self-sharpening, and the grinding ability of the grinding stone is maintained by the self-sharpening.

In creep feed grinding, the grinding wheel grinds the workpiece by colliding with it from the side toward the inside. This means that the side of the grinding wheel is prone to wear, but the bottom side of the wheel is less prone to wear. As a result, the bottom side of the grinding wheel does not generate self-sharpening edges with sufficient frequency, which can reduce the grinding ability of the grinding wheel. In addition, debris (grinding debris) generated by the grinding process can accumulate on the bottom side of the grinding wheel, causing the abrasive grains to protrude insufficiently (clogging).

As mentioned above, if the condition of the grinding wheel deteriorates during creep feed grinding, machining defects are likely to occur. For this reason, a dressing process is sometimes carried out during creep feed grinding, in which the grinding wheel is collided with a specified component to intentionally wear down the grinding wheel. However, dressing the grinding wheel interrupts the processing of the workpiece, reducing the processing efficiency.

The present invention was made in consideration of such problems, and aims to provide a method for grinding a workpiece that can improve the condition of the grinding wheel while minimizing the decline in processing efficiency.

According to one aspect of the present invention, there is provided a method for grinding a workpiece using a grinding device, the grinding device comprising: a chuck table having a holding surface for holding the workpiece and having a rotation axis set along a direction perpendicular to the holding surface; and a grinding unit having a grinding wheel including a grinding stone attached thereto and for grinding the workpiece with the grinding stone, the method including a first preparation step of adjusting a positional relationship between the chuck table and the grinding unit so that the grinding stone is positioned outside the workpiece held by the chuck table and the lower surface of the grinding stone is positioned a predetermined distance below the upper surface of the workpiece held by the chuck table; and a second preparation step of rotating the grinding wheel to rotate the grinding stone. a first grinding step of relatively moving the chuck table and the grinding unit along a direction parallel to the holding surface without rotating the chuck table, and grinding the workpiece from one end to the other end with the grinding wheel; a second preparation step of adjusting a positional relationship between the chuck table and the grinding unit after the first grinding step is performed so that a rotation axis of the chuck table and a track of the grinding wheel overlap; and a second grinding step of relatively moving the chuck table and the grinding unit along a direction perpendicular to the holding surface, while rotating the chuck table and the grinding wheel, and grinding the workpiece with the grinding wheel after the second preparation step is performed.

Preferably, in the method for grinding a workpiece, the first preparation step, the first grinding step, the second preparation step, and the second grinding step are performed in sequence two or more times.

In one aspect of the present invention, a method for grinding a workpiece includes a first grinding step in which the chuck table and the grinding unit are moved relatively in a direction parallel to the holding surface, followed by a second grinding step in which the chuck table and the grinding unit are moved relatively in a direction perpendicular to the holding surface. This promotes wear on the underside of the grinding wheel, improving the condition of the grinding wheel. In addition, in the second grinding step, the underside of the grinding wheel is dressed simultaneously with the grinding of the workpiece. Therefore, grinding of the workpiece continues even during dressing of the grinding wheel, improving processing efficiency.

FIG. 2 is a partial cross-sectional side view showing the grinding device. FIG. 2 is a perspective view showing a chuck table and a grinding unit. FIG. 3A is a side view showing the chuck table and the grinding unit in the first preparation step, and FIG. 3B is a side view showing the chuck table and the grinding unit in the first grinding step. FIG. 4A is a side view showing the chuck table and the grinding unit in the second preparation step, and FIG. 4B is a side view showing the chuck table and the grinding unit in the second grinding step.

An embodiment according to one aspect of the present invention will be described below with reference to the attached drawings. First, an example of the configuration of a grinding device that can be used in the method for grinding a workpiece according to this embodiment will be described. FIG. 1 is a partially cross-sectional side view showing a grinding device 2. In FIG. 1, the X-axis direction (first processing feed 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 (second processing feed direction, vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

The grinding device 2 includes a base 4 that supports or houses each of the components that make up the grinding device 2. A rectangular parallelepiped opening 4a is provided on the top side of the base 4. Inside the opening 4a, a chuck table (holding table) 6 is provided to hold the workpiece 11 to be machined by the grinding device 2. The top surface of the chuck table 6 is a flat surface that is roughly parallel to the X-axis and Y-axis directions, and forms a holding surface 6a that holds the workpiece 11.

A moving mechanism (moving unit) 8 is provided inside the base 4. The moving mechanism 8 is connected to the chuck table 6 and moves the chuck table 6 along the X-axis direction. Specifically, the moving mechanism 8 includes a ball screw 10 arranged along the X-axis direction. The ball screw 10 is screwed into a nut portion (not shown) connected to the chuck table 6. A pulse motor 12 that rotates the ball screw 10 is connected to an end of the ball screw 10. When the ball screw 10 is rotated by the pulse motor 12, the chuck table 6 moves along the X-axis direction.

The chuck table 6 is also connected to a rotational drive source (not shown) such as a motor. This rotational drive source rotates the chuck table 6 around a rotational axis (a rotational axis roughly parallel to the Z-axis direction) roughly perpendicular to the holding surface 6a. In other words, the rotational axis of the chuck table 6 is set along a direction perpendicular to the holding surface 6a.

A rectangular parallelepiped support structure (column) 14 is provided behind the chuck table 6 and the moving mechanism 8 (on the right side of the paper in FIG. 1). A moving mechanism (moving unit) 16 is provided on the surface side (front side) of the support structure 14. The moving mechanism 16 moves the chuck table 6 and the grinding unit 28 (described below) closer to and farther apart in a direction perpendicular to the holding surface 6a of the chuck table 6 (Z-axis direction).

Specifically, the moving mechanism 16 includes a pair of guide rails 18 fixed to the front surface side of the support structure 14. The pair of guide rails 18 are arranged along the Z axis direction while being spaced apart from each other in the Y axis direction. In addition, a flat moving plate 20 is attached to the pair of guide rails 18 in a state in which it can slide along the guide rails 18.

A nut portion 22 is provided on the back side (rear side) of the moving plate 20. A ball screw 24 is provided between the pair of guide rails 18 along the Z-axis direction, and the ball screw 24 is screwed into the nut portion 22. A pulse motor 26 that rotates the ball screw 24 is connected to the end of the ball screw 24. When the ball screw 24 is rotated by the pulse motor 26, the moving plate 20 moves (rises and falls) along the guide rails 18 in the Z-axis direction.

A grinding unit 28 that grinds the workpiece 11 is attached to the surface side (front side) of the moving plate 20. The grinding unit 28 has a hollow, cylindrical support member 30 fixed to the surface side of the moving plate 20. A cylindrical housing 32 is housed in the support member 30. The lower side of the housing 32 is supported by the bottom surface of the support member 30 via a buffer member 34 made of rubber or the like.

The housing 32 contains a cylindrical spindle 36 arranged along the Z-axis direction. The tip (lower end) of the spindle 36 is exposed from the housing 32 and protrudes downward from the lower surface of the support member 30 through an opening provided in the bottom of the support member 30. A rotational drive source (not shown), such as a motor, that rotates the spindle 36 is connected to the base (upper end) of the spindle 36.

A disk-shaped mount 38 made of metal or the like is fixed to the tip of the spindle 36. An annular grinding wheel 40 for grinding the workpiece 11 is attached to the underside of the mount 38. For example, the grinding wheel 40 is fixed to the mount 38 by a fastener such as a bolt.

The grinding wheel 40 is made of a metal such as aluminum or stainless steel and has an annular base 42 formed to have approximately the same diameter as the mount 38. The upper surface side of the base 42 is fixed to the lower surface side of the mount 38. In addition, a plurality of grinding wheels 44 are fixed to the lower surface side of the base 42. For example, the plurality of grinding wheels 44 are formed in a rectangular parallelepiped shape and are arranged in a ring shape at approximately equal intervals along the circumferential direction of the base 42.

The grinding wheel 44 is formed by fixing abrasive grains made of diamond, cBN (cubic boron nitride), etc., with a bonding material (bond material) such as metal bond, resin bond, vitrified bond, etc. However, there are no restrictions on the material, shape, structure, size, etc. of the grinding wheel 44. The number of grinding wheels 44 can also be set as desired.

The grinding wheel 40 rotates around a rotation axis (rotation axis roughly parallel to the Z-axis direction) roughly perpendicular to the holding surface 6a of the chuck table 6 by power transmitted from a rotation drive source connected to the base end of the spindle 36 via the spindle 36 and the mount 38. In other words, the rotation axis of the grinding wheel 40 is set along a direction perpendicular to the holding surface 6a. When the rotating grinding wheel 44 is brought into contact with the top surface of the workpiece 11 held by the chuck table 6, the top surface of the workpiece 11 is scraped off. This causes the workpiece 11 to be ground, resulting in a thinner workpiece 11.

Each component of the grinding device 2 (chuck table 6, moving mechanism 8, moving mechanism 16, grinding unit 28, etc.) is connected to a control unit (control unit, control device) 46 that controls the grinding device 2. The control unit 46 generates control signals that control the operation of the components of the grinding device 2, and controls the operation of the grinding device 2.

For example, the control unit 46 is configured by a computer and includes a calculation section that performs calculations necessary for the operation of the grinding device 2, and a storage section that stores various information (data, programs, etc.) used in the operation of the grinding device 2. The calculation section includes a processor such as a CPU (Central Processing Unit). The storage section includes various memories that function as a main storage device, an auxiliary storage device, etc.

The workpiece 11 is ground by the grinding unit 28 while being held by the chuck table 6. Figure 2 is a perspective view showing the chuck table 6 and the grinding unit 28.

The chuck table 6 has a cylindrical frame (main body) 48 made of metal such as SUS (stainless steel), glass, ceramics, resin, etc. A cylindrical recess 48b is provided in the center of the upper surface 48a of the frame 48. A disk-shaped holding member 50 made of a porous material such as porous ceramics is fitted into the recess 48b. The holding member 50 includes holes (flow paths) inside that communicate from the upper surface to the lower surface of the holding member 50. The upper surface 50a of the holding member 50 corresponds to a suction surface that sucks the workpiece 11 when the workpiece 11 is held by the chuck table 6.

The depth of the recess 48b and the thickness of the holding member 50 are set to be approximately the same, and the upper surface 48a of the frame 48 and the upper surface 50a of the holding member 50 are arranged on approximately the same plane. The upper surface 48a of the frame 48 and the upper surface 50a of the holding member 50 form the holding surface 6a of the chuck table 6. The holding surface 6a is connected to a suction source (not shown) such as an ejector via holes included in the holding member 50, flow paths (not shown) formed inside the frame 48, valves (not shown), etc.

The workpiece 11 is placed on the holding surface 6a of the chuck table 6. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and includes a front surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other.

The workpiece 11 is divided into a number of rectangular regions by a number of streets (planned division lines) arranged in a grid pattern so as to intersect with one another. 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 surface 11a side of each of the multiple regions divided by the streets.

By dividing the workpiece 11 along the streets, multiple device chips each equipped with a device are obtained. In addition, before dividing the workpiece 11, the back surface 11b side of the workpiece 11 is ground by the grinding device 2 to thin the workpiece 11, thereby obtaining thin device chips.

However, there are no limitations on the type, material, size, shape, structure, etc. of the workpiece 11. For example, the workpiece 11 may be a disk-shaped wafer (substrate) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. Furthermore, the workpiece 11 may be a package substrate such as a CSP (Chip Size Package) substrate or a QFN (Quad Flat Non-leaded package) substrate.

For example, the workpiece 11 is placed on the chuck table 6 so that the front surface 11a faces the holding surface 6a and the back surface 11b is exposed upward. When the suction force (negative pressure) of the suction source is applied to the holding surface 6a in this state, the workpiece 11 is sucked and held by the chuck table 6. A protective sheet made of resin or the like that protects the front surface 11a side (device) of the workpiece 11 may be attached to the front surface 11a side of the workpiece 11. In this case, the workpiece 11 is held by the holding surface 6a of the chuck table 6 via the protective sheet.

The workpiece 11 held by the chuck table 6 is ground and thinned by the grinding wheel 44 included in the grinding wheel 40. A grinding fluid supply passage (not shown) for supplying a liquid (grinding fluid) such as pure water is provided inside or near the grinding unit 28. When the workpiece 11 is ground by the grinding wheel 44, the grinding fluid is supplied to the workpiece 11 and the grinding wheel 44. This cools the workpiece 11 and the grinding wheel 44, and washes away any debris (grinding debris) generated by the grinding process.

In this embodiment, the workpiece 11 is thinned by performing creep feed grinding, in which the chuck table 6 and the grinding wheel 40 are moved relatively along a direction parallel to the holding surface 6a to grind the workpiece 11, and in-feed grinding, in which the chuck table 6 and the grinding wheel 40 are moved relatively along a direction perpendicular to the holding surface 6a to grind the workpiece 11. A specific example of a method for grinding a workpiece using the grinding device 2 is described below.

First, the positional relationship between the chuck table 6 and the grinding unit 28 is adjusted (first preparation step). FIG. 3(A) is a side view showing the chuck table 6 and the grinding unit 28 in the first preparation step. In the first preparation step, the positions of the chuck table 6 and the grinding unit 28 are adjusted so that the grinding wheel 44 is positioned outside the workpiece 11 held by the chuck table 6, and the bottom surface of the grinding wheel 44 is positioned a predetermined distance below the top surface (back surface 11b) of the workpiece 11 held by the chuck table 6.

Specifically, the position of the chuck table 6 in the X-axis direction is controlled by the movement mechanism 8 (see FIG. 1) so that the workpiece 11 is positioned in front of the grinding wheel 40 (left side of the paper in FIG. 3(A)) without overlapping with the grinding wheel 40. The position of the grinding unit 28 in the Z-axis direction is controlled by the movement mechanism 16 (see FIG. 1) so that the bottom surface of the grinding wheel 44 is positioned lower than the back surface 11b of the workpiece 11. The difference ΔH in the height positions (positions in the Z-axis direction) between the back surface 11b of the workpiece 11 and the bottom surface of the grinding wheel 44 at this time corresponds to the target value for the grinding amount of the workpiece 11 in the next first grinding step (the difference in thickness of the workpiece 11 before and after grinding).

Next, while rotating the grinding wheel 40, the chuck table 6 and the grinding unit 28 are moved relatively in a direction parallel to the holding surface 6a, and the workpiece 11 is ground from one end to the other end with the grinding wheel 44 (first grinding step). Figure 3 (B) is a side view showing the chuck table 6 and the grinding unit 28 in the first grinding step.

In the first grinding step, the workpiece 11 is ground by creep feed grinding. Specifically, the spindle 36 is first rotated to rotate the grinding wheel 40 around a rotation axis that is approximately perpendicular to the holding surface 6a of the chuck table 6. For example, the rotation speed of the grinding wheel 40 is set to 1000 rpm or more and 3000 rpm or less.

Then, while the grinding wheel 40 is rotated, the chuck table 6 is moved toward the grinding wheel 40 along the X-axis direction without rotating (first processing feed). As a result, the chuck table 6 and the grinding wheel 40 approach each other along a direction parallel to the holding surface 6a of the chuck table 6. The movement speed of the chuck table 6 (processing feed speed) is set to, for example, 1 mm/s or more and 20 mm/s or less.

When the chuck table 6 moves and one end of the workpiece 11 (the front end in the direction of movement of the workpiece 11, the right end of the paper in FIG. 3(B)) reaches the trajectory of the grinding wheel 44, the one end of the workpiece 11 is ground off by the grinding wheel 44. The chuck table 6 then moves along the X-axis direction until the other end of the workpiece 11 (the rear end in the direction of movement of the workpiece 11, the left end of the paper in FIG. 3(B)) is positioned so that it overlaps with the trajectory of the grinding wheel 44. As a result, the workpiece 11 is ground from one end to the other end, and the entire workpiece 11 is thinned.

In the above creep feed grinding, the grinding wheel 44 collides from the side of the workpiece 11 toward the inside to grind the workpiece, so the side of the grinding wheel 44 is prone to wear, but the bottom of the grinding wheel 44 is less likely to wear. In other words, the position of the bottom of the grinding wheel 44 in the Z-axis direction is less likely to fluctuate during grinding. As a result, errors in the amount of grinding of the workpiece 11 are reduced.

After grinding, arc-shaped scratches (grinding marks, saw marks) formed along the trajectory of the grinding wheel 44 remain on the back surface 11b of the workpiece 11. In creep feed grinding, the workpiece 11 is ground without the chuck table 6 rotating, so multiple grinding marks are formed roughly parallel to each other on the back surface 11b of the workpiece 11 after grinding. In this way, by aligning the direction of the grinding marks, the anisotropy of the strength of the workpiece 11 after grinding can be controlled.

However, as described above, wear is less likely to occur on the underside of the grinding wheel 44 during creep feed grinding, and so self-sharpening is less likely to occur on the underside of the grinding wheel 44. In addition, grinding debris is likely to accumulate on the underside of the grinding wheel 44, which can cause the abrasive grains of the grinding wheel 44 to protrude insufficiently (clogging). Therefore, if creep feed grinding is performed alone for a long period of time, the grinding ability of the grinding wheel 44 may decrease.

Therefore, in this embodiment, after creep feed grinding is performed, the workpiece 11 is ground by infeed grinding. This promotes wear on the underside of the grinding wheel 44, and keeps the condition of the grinding wheel 44 good.

First, after the first grinding step is performed, the positional relationship between the chuck table 6 and the grinding unit 28 is adjusted (second preparation step). FIG. 4(A) is a side view showing the chuck table 6 and the grinding unit 28 in the second preparation step. In the second preparation step, the positional relationship between the chuck table 6 and the grinding unit 28 is adjusted so that the rotation axis of the chuck table 6 and the trajectory of the grinding wheel 44 overlap. The trajectory of the grinding wheel 44 corresponds to the circular path (movement path, rotation path) through which each of the multiple grinding wheels 44 passes when the grinding wheel 40 is rotated.

Specifically, first, the grinding unit 28 is raised by the moving mechanism 16 (see FIG. 1) to move the grinding wheel 44 away from the workpiece 11. Then, the position of the chuck table 6 in the X-axis direction is controlled by the moving mechanism 8 (see FIG. 1) so that the rotation axis of the chuck table 6 overlaps with the trajectory of the grinding wheel 44. For example, the position of the chuck table 6 is adjusted so that the center of the holding surface 6a and the center of the workpiece 11 overlap with the grinding wheel 44, which is located at the front end of the grinding wheel 40 (the left end of the paper in FIG. 4(A)).

Next, while rotating the chuck table 6 and the grinding unit 28, the chuck table 6 and the grinding unit 28 are moved relative to each other in a direction perpendicular to the holding surface 6a, and the workpiece 11 is ground by the grinding wheel 44 (second grinding step). Figure 4(B) is a side view showing the chuck table 6 and the grinding unit 28 in the second grinding step.

In the second grinding step, in-feed grinding is performed on the workpiece 11. Specifically, while the chuck table 6 and the grinding wheel 40 are rotated, the grinding unit 28 is lowered along the Z-axis direction by the moving mechanism 16 (see FIG. 1) (second processing feed). This causes the chuck table 6 and the grinding wheel 40 to approach each other in a direction perpendicular to the holding surface 6a of the chuck table 6.

When the bottom surface of the grinding wheel 44 comes into contact with the top surface (back surface 11b) of the workpiece 11, the back surface 11b side of the workpiece 11 is removed by the grinding wheel 44, thinning the workpiece 11. Grinding of the workpiece 11 continues until the thickness of the workpiece 11 reaches a predetermined thickness.

In the second grinding step, wear occurs on the underside of the grinding wheel 44 that comes into contact with the workpiece 11, promoting self-sharpening and eliminating clogging. In other words, the underside of the grinding wheel 44 is dressed at the same time as the workpiece 11 is ground. As a result, the condition of the grinding wheel 44 is improved and the grinding ability of the grinding wheel 44 is restored.

The processing conditions for the workpiece 11 in the second grinding step are set so that appropriate dressing is applied to the underside of the grinding wheel 44. For example, the amount of grinding of the workpiece 11 is set to 10 μm or more and 100 μm or less, preferably 20 μm or more and 40 μm or less. The rotation speed of the chuck table 6 is set to, for example, 100 rpm or more and 300 rpm or less. Furthermore, the lowering speed (processing feed rate) of the grinding unit 28 is set to, for example, 0.2 μm/s or more and 1 μm/s or less.

In the second grinding step, it is preferable to set the rotation speed of the grinding wheel 40 to a lower speed than when performing normal in-feed grinding, the main purpose of which is to thin the workpiece 11. This promotes wear on the underside of the grinding wheel 44, and the condition of the grinding wheel 44 improves in a short period of time. Specifically, it is preferable that the rotation speed of the grinding wheel 40 is, for example, 2000 rpm or more and 3000 rpm or less.

After that, a third preparation step, which is the same as the first preparation step (see FIG. 3(A)), and a third grinding step, which is the same as the first grinding step (see FIG. 3(B)), are carried out in sequence, and creep feed grinding is resumed. In the third grinding step, the workpiece 11 is ground with the grinding wheel 44, the condition of which has been improved by carrying out the second grinding step. This improves the processing quality and suppresses the occurrence of processing defects. Then, when the workpiece 11 is thinned until its thickness reaches a predetermined target value (finishing thickness), the grinding of the workpiece 11 is completed.

Grinding of the workpiece 11 by the grinding device 2 is realized by controlling the operation of each component of the grinding device 2 with the control unit 46 (see FIG. 1). Specifically, the memory unit of the control unit 46 stores a program that describes a series of operations of each component of the grinding device 2 required to perform the first preparation step, the first grinding step, the second preparation step, the second grinding step, the third preparation step, and the third grinding step. When grinding the workpiece 11, the control unit 46 reads out the program from the memory unit, executes it, and outputs a control signal to each component of the grinding device 2. This controls the operation of the grinding device 2, and the grinding method of the workpiece according to this embodiment is automatically performed.

As described above, in the method for grinding a workpiece according to this embodiment, after a first grinding step (creep feed grinding) is performed in which the chuck table 6 and the grinding unit 28 are moved relatively along a direction parallel to the holding surface 6a, a second grinding step (in-feed grinding) is performed in which the chuck table 6 and the grinding unit 28 are moved relatively along a direction perpendicular to the holding surface 6a. This promotes wear on the underside of the grinding wheel 44, improving the condition of the grinding wheel 44.

In addition, in the second grinding step (in-feed grinding), the underside of the grinding wheel 44 is dressed simultaneously with the grinding of the workpiece 11. Therefore, grinding of the workpiece 11 continues even while the grinding wheel 44 is being dressed, improving processing efficiency.

In the grinding method of the workpiece according to this embodiment, the number of times creep feed grinding (first preparation step and first grinding step) is performed and the number of times in-feed grinding (second preparation step and second grinding step) is performed can be set appropriately according to the material of the workpiece 11, the amount of grinding, etc. In other words, the first preparation step, first grinding step, second preparation step, and second grinding step may each be performed two or more times.

For example, creep feed grinding (first preparation step and first grinding step) is performed once or twice or more times in succession, and then in-feed grinding (second preparation step and second grinding step) is performed once to improve the condition of the grinding wheel 44. Thereafter, creep feed grinding and in-feed grinding are similarly repeated in sequence to thin the workpiece 11. This allows the workpiece 11 to be thinned to the desired thickness while maintaining the condition of the grinding wheel 44 in good condition.

However, it is preferable that the final grinding process performed on the workpiece 11 is creep feed grinding (third grinding step). This reduces the variation in thickness of the workpiece 11 after grinding and controls the anisotropy of the strength of the workpiece 11 after grinding.

In addition, the structures, methods, etc. according to the above embodiments can be modified as appropriate without departing from the scope of the purpose of the present invention.

11 Workpiece 11a Surface (first surface)
11b Back side (second side)
2 Grinding device 4 Base 4a Opening 6 Chuck table (holding table)
6a Holding surface 8 Moving mechanism (moving unit)
10 ball screw 12 pulse motor 14 support structure (column)
16 Moving mechanism (moving unit)
REFERENCE SIGNS LIST 18 Guide rail 20 Moving plate 22 Nut portion 24 Ball screw 26 Pulse motor 28 Grinding unit 30 Support member 32 Housing 34 Cushioning member 36 Spindle 38 Mount 40 Grinding wheel 42 Base 44 Grinding stone 46 Control unit (control unit, control device)
48 Frame (main body)
48a Upper surface 48b Recessed portion 50 Holding member 50a Upper surface

Claims (2)

A method for grinding a workpiece using a grinding device, comprising the steps of:
The grinding device comprises:
a chuck table having a holding surface for holding the workpiece and having a rotation axis set along a direction perpendicular to the holding surface;
a grinding unit to which a grinding wheel including a grinding stone is attached and which grinds the workpiece with the grinding stone;
a first preparation step of adjusting a positional relationship between the chuck table and the grinding unit so that the grinding wheel is positioned outside the workpiece held by the chuck table and the lower surface of the grinding wheel is positioned a predetermined distance below the upper surface of the workpiece held by the chuck table;
a first grinding step in which, after the first preparation step is performed, the grinding wheel is rotated while the chuck table and the grinding unit are moved relatively in a direction parallel to the holding surface without rotating the chuck table, and the workpiece is ground from one end side to the other end side with the grinding wheel;
a second preparation step of adjusting a positional relationship between the chuck table and the grinding unit so that a rotation axis of the chuck table and a track of the grinding wheel overlap each other after the first grinding step is performed;
a second grinding step of, after carrying out the second preparation step, moving the chuck table and the grinding unit relatively along a direction perpendicular to the holding surface while rotating the chuck table and the grinding wheel, and grinding the workpiece with the grinding wheel. 2. The method for grinding a workpiece according to claim 1, wherein the first preparation step, the first grinding step, the second preparation step, and the second grinding step are carried out in sequence two or more times.

Images