TW202230504A - Grinding method for workpiece capable of suppressing reduction of processing efficiency and improving condition of grindstone - Google Patents

Abstract

The invention relates to a grinding method for workpiece, which may suppress the reduction of processing efficiency and improve the condition of grindstone. The grinding method for workpiece of the invention utilizes a grinding device to grind the workpiece. The grinding device comprises a chuck table having a holding surface for holding a workpiece and configured with a rotating shaft along a direction perpendicular to the holding surface; and, a grinding unit mounted with a grinding wheel with grindstone and using the grindstone to grind the workpiece. The grinding method for workpiece includes a first grinding step for moving the chuck table and the grinding unit relative to each other along a direction parallel to the holding surface while rotating the grinding wheel, and grinding the workpiece from one end to the other end by the grinding wheel; and, a second grinding step for moving the chuck table and the grinding unit relative to each other along a direction perpendicular to the holding surface while rotating the chuck table and the grinding wheel, and grinding the workpiece with the grindstone.

Description

Grinding method of workpiece

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

In the manufacturing process of the device wafer, a wafer in which devices are formed in a plurality of regions divided by a plurality of dicing lines (planning lines) intersecting with each other is used. By dividing the wafer along the scribe lines, a plurality of device wafers each having devices can be obtained. Component chips are assembled into various electronic devices such as mobile phones and personal computers.

In recent years, along with the miniaturization of electronic devices, thinning is also required for element wafers. Therefore, before dividing the wafer, a step of grinding and thinning the wafer using a grinding apparatus may be performed. The grinding device includes: a chuck table having a holding surface for holding a workpiece; and a grinding unit that grinds the workpiece, and the grinding unit is provided with a grinding wheel including a grinding stone. Furthermore, the grinding unit grinds the workpiece by rotating the grinding wheel and bringing the grinding stone into contact with the workpiece.

When grinding a workpiece such as a wafer with a grinding device, the positional relationship between the chuck table and the grinding unit is adjusted so that the center of the workpiece held by the chuck table overlaps the track of the grinding stone. Then, when the grinding wheel is lowered toward the holding surface of the chuck table while the chuck table and the grinding wheel are respectively rotated, the lower surface of the grinding stone contacts the upper surface side of the workpiece to grind the workpiece. This type of grinding is called feed grinding.

On the other hand, in the grinding of the workpiece, a grinding method called deep feed grinding is sometimes used. In deep feed grinding, the positions of the chuck table and the grinding unit are adjusted so that the grinding stone is positioned outside the workpiece and the lower surface of the grinding stone is positioned below the upper surface of the workpiece. relation. Then, without rotating the chuck table and rotating the grinding wheel, the chuck table is moved in a direction parallel to the holding surface (horizontal direction), thereby bringing the side and lower surface of the grinding stone into contact with the workpiece to be machined The workpiece is ground on the upper surface side of the workpiece (refer to Patent Document 1). [Previously known technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2005-28550

[Problems to be solved by the invention] The grinding stone included in the grinding wheel is formed by fixing abrasive grains made of diamond or the like with a bonding material (adhesive material). Then, grinding is performed on the workpiece by colliding the abrasive grains protruding from the bonding material of the grinding stone against the workpiece. In addition, if the grinding of the workpiece by the grinding stone is continued, the bonding material will be worn away, the exposed abrasive grains will fall off, and the abrasive grains buried in the bonding material will be newly exposed. This phenomenon is called self-sharpening, and the grinding ability of the grinding stone is maintained by the self-sharpening.

Here, in the deep feed grinding, the grinding stone collides inward from the side surface of the workpiece to grind the workpiece. Therefore, although abrasion is likely to occur on the side surface of the grinding stone, abrasion is less likely to occur on the lower surface side of the grinding stone. As a result, self-sharpening does not occur at an appropriate frequency on the lower surface side of the grinding stone, and the grinding ability of the grinding stone may be lowered. In addition, chips (grinding chips) generated by the grinding process may accumulate on the lower surface side of the grinding stone, and the protrusion of the abrasive grains may become insufficient (clogging of pores).

As described above, when the state of the grinding stone is deteriorated during deep feed grinding, machining defects are likely to occur. Therefore, in the middle of deep feed grinding, a dressing step of intentionally abrading the grinding stone by striking the grinding stone against a predetermined member may be performed. However, when dressing the grinding stone is performed, the processing of the workpiece is interrupted, and the processing efficiency is reduced.

The present invention was made in view of the above-mentioned problems, and an object of the present invention is to provide a method for grinding a workpiece capable of suppressing a decrease in machining efficiency and improving the state of a grinding stone.

[Technical means to solve the problem] According to one aspect of the present invention, there is provided a method for grinding a workpiece, which uses a grinding device to grind the workpiece, the grinding device including: a chuck table having a holding surface for holding the workpiece, and extending along the same direction as the workpiece. A rotation axis is set in the vertical direction of the holding surface; and a grinding unit is provided with a grinding wheel including a grinding stone, and the workpiece is ground with the grinding stone, and the grinding method of the workpiece includes: : The first preparation step, in which the grinding stone is positioned on the outside of the workpiece held by the chuck table, and the lower surface of the grinding stone is positioned at a distance from the workpiece held by the chuck table. The positional relationship between the chuck table and the grinding unit is adjusted by a predetermined distance below the upper surface of the upper surface; in the first grinding step, after the first preparation step is performed, the grinding wheel is rotated while the chuck is rotated. The table and the grinding unit are relatively moved along a direction parallel to the holding surface, and the workpiece is ground from one end side to the other end side with the grinding stone; the second preparation step is to perform the first grinding After the step, adjust the positional relationship between the chuck table and the grinding unit in such a way that the rotation axis of the chuck table overlaps the orbit of the grinding stone; and a second grinding step, which is performed after the second preparation step is performed , while rotating the chuck table and the grinding wheel, the chuck table and the grinding unit are moved relatively in a direction perpendicular to the holding surface, and the workpiece is ground with the grinding stone.

Moreover, in the grinding method of the workpiece, preferably, the first preparation step, the first grinding step, the second preparation step, and the second grinding step are each carried out twice or more.

[Inventive effect] In the method for grinding a workpiece according to an aspect of the present invention, after the first grinding step of relatively moving the chuck table and the grinding unit in a direction parallel to the holding surface is performed, the chuck table and the grinding unit are subjected to grinding. A second grinding step in which the unit moves relatively in a direction perpendicular to the holding surface. Thereby, abrasion of the lower surface side of a grinding stone is accelerated, and the state of a grinding stone is improved. Furthermore, in the second grinding step, the dressing of the lower surface side of the grinding stone and the grinding of the workpiece are simultaneously performed. Therefore, the grinding of the workpiece is continued even in the dressing of the grinding stone, and the processing efficiency is improved.

Hereinafter, embodiments of one aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of a grinding apparatus that can utilize the method for grinding a workpiece of the present embodiment will be described. FIG. 1 is a partial cross-sectional side view showing the grinding apparatus 2 . In addition, in FIG. 1, the X-axis direction (the first machining feed direction, the first horizontal direction, the front-rear direction) and the Y-axis direction (the second horizontal direction, the left-right direction) are mutually perpendicular directions. In addition, the Z-axis direction (second machining feed direction, vertical direction, vertical direction, height direction) is a direction perpendicular to the X-axis direction and the Y-axis direction.

The grinding apparatus 2 is provided with the base 4 which supports or accommodates each component which comprises the grinding apparatus 2 . A rectangular parallelepiped-shaped opening 4 a is provided on the upper surface side of the base 4 . Further, a chuck table (holding table) 6 for holding the workpiece 11 to be processed by the grinding device 2 is provided inside the opening 4 a. The upper surface of the chuck table 6 is a flat surface substantially parallel to the X-axis direction and the Y-axis direction, and constitutes a holding surface 6 a for holding the workpiece 11 .

Furthermore, a moving mechanism (moving means) 8 is provided inside the base 4 . The moving mechanism 8 is connected to the chuck table 6 and moves the chuck table 6 in 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 to a nut portion (not shown) connected to the chuck table 6 . In addition, a pulse motor 12 for rotating the ball screw 10 is connected to the end of the ball screw 10 . When the ball screw 10 is rotated by the pulse motor 12, the chuck table 6 moves in the X-axis direction.

In addition, a rotational drive source (not shown) such as a motor is connected to the chuck table 6 . This rotational drive source rotates the chuck table 6 about a rotation axis (a rotation axis substantially parallel to the Z-axis direction) substantially perpendicular to the holding surface 6a. That is, the rotation axis of the chuck table 6 is set along the direction perpendicular to the holding surface 6a.

A rectangular parallelepiped-shaped support structure (column body) 14 is provided behind the chuck table 6 and the moving mechanism 8 (on the right side of the drawing in FIG. 1 ). Furthermore, a moving mechanism (moving unit) 16 is provided on the front side (front surface side) of the support structure 14 . The moving mechanism 16 approaches and separates the chuck table 6 and the grinding unit 28 described later in a direction (Z-axis direction) perpendicular to the holding surface 6 a of the chuck table 6 .

Specifically, the moving mechanism 16 includes a pair of guide rails 18 fixed to the front side of the support structure 14 . The pair of guide rails 18 are arranged along the Z-axis direction in a state of being separated from each other in the Y-axis direction. In addition, the plate-shaped moving plate 20 is attached to the pair of guide rails 18 in a state slidable along the guide rails 18 .

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

A grinding unit 28 for grinding the workpiece 11 is mounted on the front side (front surface side) of the moving plate 20 . The grinding unit 28 includes a hollow cylindrical support member 30 fixed to the front side of the moving plate 20 . A cylindrical case 32 is accommodated in the support member 30 . The lower surface side of the casing 32 is supported by the lower surface of the support member 30 via a buffer member 34 made of rubber or the like.

A cylindrical main shaft 36 arranged along the Z-axis direction is accommodated in the housing 32 . The front end (lower end) of the main shaft 36 is exposed from the casing 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 . In addition, a rotational drive source (not shown) such as a motor for rotating the main shaft 36 is connected to the base end (upper end) of the main shaft 36 .

A disk-shaped mount 38 made of metal or the like is fixed to the front end of the main shaft 36 . Furthermore, an annular grinding wheel 40 for grinding the workpiece 11 is mounted on the lower surface side of the mount 38 . For example, the grinding wheel 40 is fixed to the mount 38 by a fixing tool such as a bolt.

The grinding wheel 40 includes an annular base 42 made of metal such as aluminum or stainless steel and formed to have substantially 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 stones 44 are fixed to the lower surface side of the base 42 . For example, the plurality of grinding stones 44 are formed in a rectangular parallelepiped shape, and are arranged in a ring shape at substantially equal intervals along the circumferential direction of the base 42 .

The grinding stone 44 is formed by fixing abrasive grains made of diamond, cBN (cubic Boron Nitride, cubic boron nitride) or the like with a bonding material (adhesive material) such as a metal bond, a resin bond, or a vitrified bond. However, the material, shape, structure, size, etc. of the grinding stone 44 are not limited. In addition, the number of grinding stones 44 may be arbitrarily set.

The grinding wheel 40 is driven by the power transmitted from the rotational drive source connected to the base end portion of the main shaft 36 through the main shaft 36 and the mounting member 38 , and revolves around a rotation axis (which is substantially perpendicular to the holding surface 6 a of the chuck table 6 ). The Z axis direction is roughly parallel to the rotation axis) to rotate. That is, the rotation axis of the grinding wheel 40 is set along the direction perpendicular to the holding surface 6a. Then, when the rotating grinding stone 44 is brought into contact with the upper surface side of the workpiece 11 held by the chuck table 6, the upper surface side of the workpiece 11 is scraped off. Thereby, the grinding process is performed on the workpiece 11, and the workpiece 11 is thinned.

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

For example, the control unit 46 is constituted by a computer, and includes: a calculation unit that performs calculations required for the operation of the grinding device 2 ; and a memory unit that stores various information (data, programs, etc.) used for the operation of the grinding device 2 Wait). The arithmetic unit is constituted by including a processor such as a CPU (Central Processing Unit, central processing unit). In addition, the memory unit is configured to include various types of memory that function as a main memory device, an auxiliary memory device, and the like.

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

The chuck table 6 includes a cylindrical frame body (main body portion) 48 made of metal such as SUS (stainless steel), glass, ceramics, resin, or the like. A columnar recessed portion 48b is provided in the center portion on the upper surface 48a side of the frame body 48 . In addition, a disc-shaped holding member 50 made of a porous member such as porous ceramics is fitted into the recessed portion 48b. The holding member 50 internally includes a hole (flow path) that communicates from the upper surface to the lower surface of the holding member 50 . The upper surface 50 a of the holding member 50 corresponds to a suction surface that attracts the workpiece 11 when the workpiece 11 is held by the chuck table 6 .

The depth of the recessed portion 48b and the thickness of the holding member 50 are set to be substantially the same, and the upper surface 48a of the frame body 48 and the upper surface 50a of the holding member 50 are arranged on substantially the same plane. Furthermore, the holding surface 6 a of the chuck table 6 is constituted by the upper surface 48 a of the frame body 48 and the upper surface 50 a of the holding member 50 . The holding surface 6a is connected to a suction source (not shown) such as an ejector through a hole included in the holding member 50, a flow path (not shown) formed inside the frame 48, a valve (not shown), etc. .

The workpiece 11 is arranged on the holding surface 6 a 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 substantially parallel to each other.

The workpiece 11 is divided into a plurality of rectangular regions by a plurality of scribe lanes (planned dividing lines) arranged in a grid shape so as to intersect with each other. In addition, IC (Integrated Circuit, integrated circuit), LSI (Large Scale Integration, large-scale integrated circuit), LED (Light Emitting Diode, light-emitting) are formed on the front surface 11a side of the plurality of regions divided by the scribe lines, respectively. Diodes), MEMS (Micro Electro Mechanical Systems, Micro Electro Mechanical Systems) components and other components (not shown).

By dividing the workpiece 11 along the scribe lines, a plurality of element wafers each including elements can be obtained. Furthermore, before dividing the workpiece 11, the workpiece 11 is thinned by grinding the back surface 11b side of the workpiece 11 by the grinding device 2, whereby a thinned element wafer can be obtained.

However, the type, material, size, shape, structure, etc. of the workpiece 11 are not limited. For example, the workpiece 11 may be a disk-shaped wafer (substrate) made of semiconductors other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, or the like. In addition, the workpiece 11 may be a package substrate such as a CSP (Chip Size Package) substrate and a QFN (Quad Flat Non-leaded package) substrate.

For example, the workpiece 11 is arranged on the chuck table 6 so that the front surface 11a side faces the holding surface 6a and the back surface 11b side is exposed upward. When the suction force (negative pressure) of the suction source is applied to the holding surface 6 a in this state, the workpiece 11 is sucked and held by the chuck table 6 . In addition, the protection sheet which is made of resin etc. and which protects the front surface 11a side (element) of the workpiece 11 may be pasted on the front surface 11a side of the workpiece 11 . In this case, the workpiece 11 is held on 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 stone 44 included in the grinding wheel 40 . In addition, a grinding fluid supply path (not shown) for supplying a liquid (grinding fluid) such as pure water is provided in or near the grinding unit 28 . When the workpiece 11 is ground by the grinding stone 44 , the grinding fluid is supplied to the workpiece 11 and the grinding stone 44 . Thereby, the workpiece 11 and the grinding stone 44 are cooled, and chips (grinding chips) generated by the grinding process are washed away.

In the present embodiment, the workpiece 11 is thinned by performing deep-feed grinding and feed grinding in which the chuck table 6 and the grinding wheel 40 are aligned with the holding surface 6a. The workpiece 11 is ground by moving relatively in a parallel direction, and the feed grinding is performed by moving the chuck table 6 and the grinding wheel 40 relatively in a direction perpendicular to the holding surface 6 a to grind the workpiece 11 . Hereinafter, a specific example of the grinding method of the workpiece using the grinding device 2 will be described.

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 grinding stone 44 is positioned outside the workpiece 11 held by the chuck table 6 , and the lower surface of the grinding stone 44 is positioned at a distance from the workpiece 11 held by the chuck table 6 . The positions of the chuck table 6 and the grinding unit 28 are adjusted so that the upper surface (back surface 11b) of the upper surface (back surface 11b) is below a predetermined distance.

Specifically, the chuck is controlled by the moving mechanism 8 (refer to FIG. 1 ) so that the workpiece 11 is disposed in front of the grinding wheel 40 (the left side of the drawing in FIG. 3(A) ) without overlapping the grinding wheel 40 . The position of the stage 6 in the X-axis direction. Then, the position of the grinding unit 28 in the Z-axis direction is controlled by the moving mechanism 16 (refer to FIG. 1 ) so that the lower surface of the grinding stone 44 is positioned below the back surface 11 b of the workpiece 11 . The difference ΔH between the height position (position in the Z-axis direction) of the back surface 11 b of the workpiece 11 and the lower surface of the grinding stone 44 at this time corresponds to the subsequent grinding of the workpiece 11 in the first grinding step The target value of the amount (difference in the 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 relatively moved in a direction parallel to the holding surface 6a, and the workpiece 11 is ground from one end side to the other end by the grinding stone 44 side (first grinding step). FIG. 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 deep feed grinding. Specifically, first, by rotating the main shaft 36 , the grinding wheel 40 is rotated about a rotation axis substantially perpendicular to the holding surface 6 a of the chuck table 6 . For example, the rotational speed of the grinding wheel 40 is set to 1000 rpm or more and 3000 rpm or less.

Then, in a state where the grinding wheel 40 is rotated, the chuck table 6 is moved to the grinding wheel 40 side in the X-axis direction without rotating (first machining feed). Thereby, the chuck table 6 and the grinding wheel 40 approach each other in a direction parallel to the holding surface 6 a of the chuck table 6 . In addition, the moving speed (processing feed speed) of the chuck table 6 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 moving direction of the workpiece 11 , the right end on the paper surface in FIG. 3(B) ) reaches the track of the grinding stone 44 , the grinding stone 44 One end of the workpiece 11 is shaved off. Then, the chuck table 6 is moved along the X-axis direction until the other end of the workpiece 11 (the rear end in the moving direction of the workpiece 11 , the left end on the paper surface in FIG. 3(B) ) is arranged on the grinding stone 44 up to the position where the tracks overlap. As a result, the workpiece 11 is ground from one end side to the other end side, and the entire workpiece 11 is thinned.

In the above-mentioned deep feed grinding, since the grinding stone 44 strikes the workpiece from the side surface of the workpiece 11 toward the inside to grind the workpiece, abrasion is likely to occur on the side surface of the grinding stone 44 . The lower surface side is less prone to wear. That is, during grinding, the position of the lower surface of the grinding stone 44 in the Z-axis direction is less likely to fluctuate. As a result, the error of the grinding amount of the workpiece 11 is reduced.

In addition, arc-shaped flaws (grinding marks, saw marks) formed along the trajectory of the grinding stone 44 remain on the back surface 11 b side of the workpiece 11 after grinding. Furthermore, in the deep feed grinding, since the workpiece 11 is ground without the chuck table 6 rotating, a plurality of grinding marks are formed on the back surface 11b side of the workpiece 11 after grinding. In this way, the anisotropy of the strength of the workpiece 11 after grinding can be controlled by aligning the directions of the grinding marks.

However, as described above, in the deep feed grinding, self-sharpening is less likely to occur on the lower surface side of the grinding stone 44 because abrasion is less likely to occur on the lower surface side of the grinding stone 44 . In addition, grinding debris tends to accumulate on the lower surface side of the grinding stone 44, and the protrusion of the abrasive grains of the grinding stone 44 may become insufficient (clogging of pores). Therefore, if only deep feed grinding is performed for a long time, the grinding ability of the grinding stone 44 may be lowered.

Therefore, in the present embodiment, after the deep feed grinding is performed, the workpiece 11 is ground by the feed grinding. Thereby, abrasion of the lower surface side of the grinding stone 44 is accelerated, and the state of the grinding stone 44 is maintained favorably.

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 orbit of the grinding stone 44 overlap. In addition, the orbit of the grinding stone 44 corresponds to an annular path (movement path, rotation path) through which each of the plurality of grinding stones 44 passes when the grinding wheel 40 is rotated.

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

Next, while rotating the chuck table 6 and the grinding unit 28, the chuck table 6 and the grinding unit 28 are relatively moved in the direction perpendicular to the holding surface 6a, and the workpiece 11 is ground by the grinding stone 44 (No. two grinding steps). FIG. 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, feed grinding is performed on the workpiece 11 . Specifically, in a state in which the chuck table 6 and the grinding wheel 40 are rotated, the grinding unit 28 is lowered in the Z-axis direction by the moving mechanism 16 (see FIG. 1 ) (second machining feed). Thereby, the chuck table 6 and the grinding wheel 40 approach each other in a direction perpendicular to the holding surface 6 a of the chuck table 6 .

When the lower surface of the grinding stone 44 contacts the upper surface (back surface 11 b ) of the workpiece 11 , the back surface 11 b side of the workpiece 11 is shaved by the grinding stone 44 to thin the workpiece 11 . Then, the grinding of the workpiece 11 is continued until the thickness of the workpiece 11 becomes a predetermined thickness.

In the above-described second grinding step, abrasion occurs on the lower surface side of the grinding stone 44 in contact with the workpiece 11, self-sharpening is promoted, and pore clogging is solved. That is, the dressing of the lower surface side of the grinding stone 44 is performed simultaneously with the grinding of the workpiece 11 . As a result, the state of the grinding stone 44 is improved, and the grinding ability of the grinding stone 44 is restored.

The processing conditions of the workpiece 11 in the second grinding step are set so that appropriate dressing is performed on the lower surface side of the grinding stone 44 . For example, the grinding amount 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. In addition, the rotational speed of the chuck table 6 is set to, for example, 100 rpm or more and 300 rpm or less. In addition, the descending speed (processing feed speed) of the grinding unit 28 is set to, for example, 0.2 μm/s or more and 1 μm/s or less.

In addition, in the second grinding step, it is preferable to set the rotational speed of the grinding wheel 40 to a low speed compared to the case of performing general feed grinding for the main purpose of thinning the workpiece 11 . Thereby, the abrasion of the lower surface side of the grinding stone 44 is promoted, and the state of the grinding stone 44 is improved in a short time. Specifically, the rotational speed of the grinding wheel 40 is preferably 2000 rpm or more and 3000 rpm or less, for example.

After that, the third preparation step having the same contents as the first preparation step (refer to FIG. 3(A) ) and the third grinding step having the same contents as the first grinding step (refer to FIG. 3(B) ) are sequentially performed, and again Start deep feed and slow feed grinding. In addition, in the third grinding step, the workpiece 11 is ground with the grinding stone 44 whose state has been improved by implementing the second grinding step. Thereby, processing quality is improved, and generation|occurrence|production of a processing defect is suppressed. Then, when the workpiece 11 is thinned until the thickness of the workpiece 11 becomes a predetermined target value (finished thickness), the grinding process of the workpiece 11 is completed.

The above-described grinding of the workpiece 11 by the grinding device 2 is realized by controlling the operations of the respective components of the grinding device 2 by the control unit 46 (see FIG. 1 ). Specifically, a program is stored in the memory unit of the control unit 46, and the program describes the steps 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. A series of operations of each component of the grinding device 2 is required. Then, when the grinding of the workpiece 11 is performed, the control unit 46 reads and executes the program from the memory unit, and outputs control signals to the respective components of the grinding device 2 . Thereby, the operation of the grinding apparatus 2 is controlled, and the grinding method of the workpiece of the present embodiment is automatically implemented.

As described above, in the method for grinding a workpiece according to the present embodiment, the first grinding step (deep feed grinding) in which the chuck table 6 and the grinding unit 28 are relatively moved in a direction parallel to the holding surface 6a is carried out. ), a second grinding step (feed grinding) in which the chuck table 6 and the grinding unit 28 are relatively moved in a direction perpendicular to the holding surface 6 a is carried out. Thereby, abrasion on the lower surface side of the grinding stone 44 is promoted, and the state of the grinding stone 44 is improved.

In addition, in the second grinding step (feed grinding), the dressing of the lower surface side of the grinding stone 44 is carried out simultaneously with the grinding of the workpiece 11 . Therefore, the grinding of the workpiece 11 is continued even during the dressing of the grinding stone 44, and the machining efficiency is improved.

Further, in the method for grinding a workpiece according to the present embodiment, the number of times of performing deep feed grinding (the first preparation step and the first grinding step) and the number of times of the feed grinding (the second preparation step and the second grinding step) The number of times of execution can be appropriately set according to the material of the workpiece 11, the amount of grinding, and the like. That is, each of the first preparation step, the first grinding step, the second preparation step, and the second grinding step may be implemented twice or more.

For example, after the deep feed grinding (the first preparation step and the first grinding step) is performed one or more times in a row, the first feed grinding (the second preparation step and the second grinding step) is performed to improve the grinding stone. 44 status. Thereafter, the workpiece 11 is thinned by sequentially repeating the deep feed grinding and feed grinding in the same manner. Thereby, the state of the grinding stone 44 can be maintained favorably, and the workpiece 11 can be thinned to a desired thickness.

However, the final grinding operation performed on the workpiece 11 is preferably deep feed grinding (third grinding step). Thereby, the variation in the thickness of the workpiece 11 after the grinding process is reduced, and the anisotropy of the strength of the workpiece 11 after the grinding process is controlled.

In addition, the structure, method, etc. of the above-mentioned embodiment can be suitably changed and implemented in the range which does not deviate from the objective of this invention.

11: Processed objects 11a: Front (first side) 11b: Back (Second Side) 2: Grinding device 4: Abutment 4a: Opening 6: Chuck table (holding table) 6a: Keep Face 8: Moving mechanism (moving unit) 10: Ball screw 12: Pulse motor 14: Support structure (column) 16: Mobile mechanism (mobile unit) 18: Rails 20: Mobile board 22: Nut part 24: Ball screw 26: Pulse motor 28: Grinding unit 30: Support member 32: Shell 34: Buffer member 36: Spindle 38: Mounting pieces 40: Grinding wheel 42: Abutment 44: Grinding Stone 46: Control unit (control unit, control device) 48: Frame (body part) 48a: upper surface 48b: Recess 50: Keeping Components 50a: upper surface

FIG. 1 is a partial cross-sectional side view showing a grinding apparatus. FIG. 2 is a perspective view showing a chuck table and a grinding unit. FIG. 3(A) is a side view showing the chuck table and the grinding unit in the first preparation step, and FIG. 3(B) is a side view showing the chuck table and the grinding unit in the first grinding step. 4(A) is a side view showing the chuck table and the grinding unit in the second preparation step, and FIG. 4(B) is a side view showing the chuck table and the grinding unit in the second grinding step.

2: Grinding device

4: Abutment

4a: Opening

6: Chuck table (holding table)

6a: Keep Face

8: Moving mechanism (moving unit)

10: Ball screw

11: Processed objects

12: Pulse motor

14: Support structure (column)

16: Moving mechanism (moving unit)

18: Rails

20: Mobile board

22: Nut part

24: Ball screw

26: Pulse motor

28: Grinding unit

30: Support member

32: Shell

34: Buffer member

36: Spindle

38: Mounting pieces

40: Grinding wheel

42: Abutment

44: Grinding Stone

46: Control unit (control unit, control device)

Claims (2)

A method for grinding a workpiece, which uses a grinding device to grind the workpiece, and is characterized in that: The grinding device has: a chuck table having a holding surface for holding the workpiece, and a rotation axis is set along a direction perpendicular to the holding surface; and A grinding unit equipped with a grinding wheel including a grinding stone, and grinding the workpiece with the grinding stone, The grinding method of the workpiece includes: In the first preparation step, the grinding stone is positioned on the outside of the workpiece held by the chuck table, and the lower surface of the grinding stone is positioned at a distance from the workpiece held by the chuck table. Adjust the positional relationship between the chuck table and the grinding unit by means of a predetermined distance below the upper surface; The first grinding step, after the first preparation step is carried out, while rotating the grinding wheel, the chuck table and the grinding unit are relatively moved in a direction parallel to the holding surface, and the grinding is performed with the grinding wheel. The stone grinds the workpiece from one end side to the other end side; A second preparation step, which, after the first grinding step is performed, adjusts the positional relationship between the chuck table and the grinding unit in such a way that the rotation axis of the chuck table overlaps the orbit of the grinding stone; and In the second grinding step, after the second preparation step is performed, the chuck table and the grinding unit are relatively moved in a direction perpendicular to the holding surface while the chuck table and the grinding wheel are rotated, The workpiece is ground with the grinding stone. The grinding method of the workpiece as claimed in claim 1, wherein, The first preparation step, the first grinding step, the second preparation step, and the second grinding step are each implemented twice or more.

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