Holding pad and conveying device

Abstract

To provide a holding pad which is excellent in retainability for a workpiece having irregularities on an upper surface and a workpiece having a small thickness, and to provide a transport device.SOLUTION: A holding pad (40) suctions and holds an upper surface of a workpiece (W) and includes: a suction plate (41) having a suction surface (44) which suctions and holds the upper surface of the workpiece; a suction passage (45) which is formed within the suction plate and allows the suction surface to communicate with a suction source (46); and a plate-like ring elastic plate (70) which is disposed at an outer peripheral edge of the suction plate in a ring shape spreading toward its bottom; and a ring nozzle (60) which is disposed at the outer side of the ring elastic plate in a horizontal direction and supplies water to the ring shape.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a holding pad for holding a workpiece and a transfer device including the holding pad.

Background Art

[0002] A grinding device for grinding a wafer (workpiece) held on the holding surface of a chuck table with a grinding wheel includes a loading mechanism for loading the wafer onto the chuck table and an unloading mechanism for unloading the ground wafer from the chuck table. The loading mechanism and the unloading mechanism include a holding pad for sucking and holding the upper surface of the wafer. In addition, the grinding device may include a transfer mechanism that performs loading and unloading with a single holding pad. Hereinafter, the general term for such a loading mechanism, unloading mechanism, and transfer mechanism is referred to as a transfer device.

[0003] In a conventional transfer device, when there are irregularities on the upper surface of the wafer, air leaks at the irregularities, resulting in a problem that the suction force by the holding pad weakens. As a solution to this problem, there is a device that includes an annular (ring-shaped) elastic body on the suction surface side of the holding pad and communicates the portion surrounded by the elastic body with a suction source to suppress the leakage of the suction force (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described in Patent Document 1, when an annular elastic body protruding from the suction surface of the holding pad is provided, when a wafer (workpiece) that has been thinned by grinding is sucked up, the wafer is pressed down at the location of the elastic body, resulting in partial stress on the wafer, which may cause the wafer to deform or be damaged. In addition, Patent Document 1 uses an O-ring as the elastic body, and if there are irregularities on the upper surface of the wafer (workpiece), a gap may form between the elastic body and the wafer, making it impossible to suck up and hold the wafer.

[0006] The present invention has been made in view of the above, and aims to provide a holding pad and a conveying device that have excellent holding properties for workpieces with uneven upper surfaces or workpieces with small thickness. [Means for solving the problem]

[0007] One aspect of the present invention is a holding pad for suction holding the upper surface of a workpiece, comprising: a suction plate having a suction surface for suction holding the upper surface of the workpiece; a suction passage formed inside the suction plate and communicating the suction surface to a suction source; and a ring-shaped, flared arrangement around the outer edge of the suction plate. The lower end is brought into contact with the upper surface of the workpiece. It comprises a plate-shaped ring elastic plate material and a ring nozzle positioned horizontally on the outside of the ring elastic plate material to supply water in a ring shape. The ring elastic plate material comprises a cylindrical main body and a lip portion provided on the lower end side of the main body, the lower end of which contacts the upper surface of the workpiece, and the ring nozzle supplies the water to the lower end of the lip portion. It is characterized by the following.

[0008] One aspect of the present invention is a conveying device for attaching the above-mentioned holding pad and conveying a workpiece from a first position to a second position, comprising a moving mechanism for moving the holding pad from the first position to the second position and a control unit, wherein the control unit brings the suction surface into contact with the upper surface of the workpiece at the first position and the ring elastic plate material The lip portion The lower end is pressed against the upper surface of the outer circumference of the workpiece, and the ring nozzle is used to... At the lower end of the lip portion A holding control unit that supplies water to connect the suction surface to a suction source and holds the workpiece by suction on the suction surface, and before moving the holding pad from the first position to the second position, from the ring nozzle At the lower end of the lip portion The system includes a water supply control unit that stops the supply of water, and a movement control unit that moves the retaining pad from the first position to the second position. [Effects of the Invention]

[0009] According to the holding pad of the present invention, a ring-shaped elastic plate material is arranged in a ring-like, flared shape around the outer edge of the suction plate, and a ring nozzle is arranged outside the ring-shaped elastic plate material to supply water in a ring shape, thereby efficiently suppressing leakage of suction force and improving the holding performance for workpieces with uneven surfaces or thin workpieces.

[0010] Furthermore, according to the conveying device of the present invention, in addition to the effects of the holding pad described above, water supply from the ring nozzle is stopped when moving the holding pad from the first position to the second position, thus saving water consumption. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing a part of the grinding apparatus of this embodiment. [Figure 2] This is a cross-sectional view showing the state of the workpiece held on the holding table before it is transported by the transport device of the grinding machine. [Figure 3] This is a cross-sectional view showing the state in which the holding pad of the conveying device has descended and is in contact with the workpiece. [Figure 4] This is a cross-sectional view showing the state in which the holding pad, which is holding the workpiece by suction, is raised. [Figure 5] This is a magnified cross-sectional view showing the holding pad detached from the workpiece. [Figure 6] This is an enlarged cross-sectional view showing the holding pad in contact with the workpiece. [Figure 7] This block diagram shows the hardware configuration of the grinding apparatus according to this embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, with reference to the accompanying drawings, the holding pad and the transfer device according to the present embodiment will be described. FIGS. 1 to 6 are cross-sectional views showing a part of a grinding device including the holding pad and the transfer device according to the present embodiment, and FIG. 7 is a block diagram conceptually showing the hardware configuration of the grinding device.

[0013] The grinding device 1 shown in FIGS. 1 to 4 and FIG. 7 is a processing device that grinds a plate-shaped workpiece W that is a workpiece. When performing grinding on the grinding device 1, the surface facing upward is defined as the upper surface of the workpiece W, and the opposite surface is defined as the lower surface of the workpiece W.

[0014] The grinding device 1 includes a holding table 2 that holds the lower surface of the workpiece W, a grinding mechanism 3 (FIG. 1) that grinds the upper surface of the workpiece W held by the holding table 2, a transfer device 4 (FIGS. 2 to 4) that sucks and holds the upper surface of the workpiece W and transfers the workpiece W, a workpiece supply unit 5 (FIG. 7) that supplies the workpiece W to the grinding device 1, and a spinner cleaning unit 6 (FIG. 7) that cleans the workpiece W.

[0015] The operation of transporting the workpiece W before grinding to the holding table 2 is referred to as loading, and the operation of transporting the workpiece W ground by the grinding mechanism 3 out from above the holding table 2 is referred to as unloading. Transfer is a concept including at least one of loading and unloading. The transfer device 4 of the present embodiment can be used for both loading and unloading the workpiece W to and from the holding table 2.

[0016] In the grinding device 1, the workpiece W supplied from the workpiece supply unit 5 is placed (loaded) on the holding table 2 using the transfer device 4, the upper surface of the workpiece W is ground using the grinding mechanism 3, and the workpiece W after grinding is unloaded from above the holding table 2 using the transfer device 4. Such a series of operations is controlled by a control unit 80 (FIG. 7) that overall controls the grinding device 1. The control unit 80 is composed of a processor that executes various processes and a storage unit (memory) that stores various parameters, programs, and the like. Regarding the operations of each part described below, when the subject of control is not specified, it is assumed that the operation is controlled by a control signal sent from the control unit 80.

[0017] Figure 1 shows a state in which a workpiece W held on a holding table 2 is being ground by a grinding mechanism 3. Figures 2 to 4 show the flow of the operation of transporting (unloading) the workpiece W held on the holding table 2 by a transfer device 4. The holding table 2 is movable in the horizontal direction and can be moved to a region (Figure 1) corresponding to the grinding of the workpiece W by the grinding mechanism 3 and a region (Figures 2 to 4) corresponding to the transfer of the workpiece W by the transfer device 4.

[0018] The holding table 2 has a holding portion 22 formed of a porous member within a recess 21 provided on the upper surface side of a frame body 20. The frame body 20 and the holding portion 22 are in a disc shape. The upper surface side of the holding portion 22 serves as a holding surface 23 for sucking and holding the workpiece W. A flow path 24 is formed inside the frame body 20. The flow path 24 branches into a plurality and opens to the bottom surface side of the recess 21. The flow path 24 is connected to a suction source 25, an air supply source 26, and a water supply source 27 via opening and closing valves 251, 261, and 271.

[0019] When the opening and closing valve 251 is opened to operate the suction source 25, the air on the holding portion 22 side is sucked through the flow path 24, and the workpiece W can be sucked and held from below by the suction force acting on the holding surface 23.

[0020] When the opening and closing valve 261 is opened to operate the air supply source 26, the air supplied through the flow path 24 jets out from the holding surface 23. When the opening and closing valve 271 is opened to operate the water supply source 27, the water supplied through the flow path 24 jets out from the holding surface 23. It is also possible to operate the air supply source 26 and the water supply source 27 simultaneously to jet out a mixed fluid of air and water from the holding surface 23.

[0021] As shown in Figure 1, the grinding mechanism 3 includes a spindle 30, a disc-shaped grinding wheel 32 mounted to the lower part of the spindle 30 via a mount 31, and a grindstone 33 fixedly provided in an annular shape below the grinding wheel 32.

[0022] The spindle 30 is supported by a support part (not shown) in such a way that it can move vertically and rotate around a vertical axis extending in the vertical direction. The spindle 30 is rotated by the spindle drive motor 34 (Figure 7), and the spindle 30 is moved up and down by the lifting mechanism 35 (Figure 7). The grinding wheel 33 is brought into contact with the upper surface of the workpiece W, and the spindle 30 is rotated, allowing the workpiece W to be ground while being pressed by the grinding wheel 33.

[0023] As shown in Figures 2 to 4, a holding pad 40 is attached to the conveying device 4. Figures 5 and 6 are enlarged views of the holding pad 40 and a portion of the holding table 2.

[0024] The retaining pad 40 has a disc-shaped suction plate 41, and a recess 42 is formed on the lower surface side of the suction plate 41. As shown in Figures 5 and 6, the recess 42 has a cylindrical internal space surrounded by an inner circumferential surface 421 and a bottom surface 422. The recess 42 opens downward, and a retaining part 43 is held inside the recess 42. The outer circumferential surface of the retaining part 43 fits into the inner circumferential surface 421 of the recess 42 and is held in place. The lower surface of the retaining part 43 constitutes a suction surface 44 that sucks and holds the workpiece W.

[0025] The holding portion 43 is configured to exert a suction force on the suction surface 44. For example, the holding portion 43 is formed from a porous material. Alternatively, the holding portion 43 is constructed by forming multiple suction ports and suction grooves in a plate made of a material such as ceramics or resin.

[0026] A flow path 45 (suction passage) is formed inside the suction plate 41, connecting the suction surface 44 to the suction source 46 and the air supply source 47. The flow path 45 is composed of the space between the bottom surface 422 of the recess 42 and the upper surface of the holding portion 43, and a hole extending upward from this space. The flow path 45 is connected to the suction source 46 via an on / off valve 461 and to the air supply source 47 via an on / off valve 471.

[0027] The conveying device 4 is equipped with a moving mechanism 50 that moves the holding pad 40. The movement of the holding pad 40 by the moving mechanism 50 includes at least vertical movement. The moving mechanism 50 can further cause the holding pad 40 to perform rotational movements around a vertical axis extending in the vertical direction. For example, rotational movements by the moving mechanism 50 can move the holding pad 40 between a position above the holding table 2 and a position above the spinner cleaning unit 6.

[0028] The moving mechanism 50 includes an arm 51 that supports the retaining pad 40. The arm 51 extends horizontally, and multiple through holes 511 that penetrate vertically are formed at the tip of the arm 51. For example, three through holes 511 are provided at approximately equal intervals in the circumferential direction around a vertical axis passing through the center of the retaining pad 40. A slide shaft 52 passes through each through hole 511, and the lower end of the slide shaft 52 is connected to the upper surface of the suction plate 41. The upper end of the slide shaft 52 has a head 521 with a large diameter, and the head 521 abuts against the upper surface of the arm 51.

[0029] A cylindrical coil spring 53 is positioned between the upper surface of the suction plate 41 and the lower surface of the arm 51, surrounding each slide shaft 52. Each coil spring 53 biases the suction plate 41 downward relative to the arm 51, pressing the head 521 of the slide shaft 52 against the upper surface of the arm 51. This holds the retaining pad 40 in a fixed position in the vertical direction relative to the arm 51. Furthermore, when the retaining pad 40 receives downward pressure, it is possible for the retaining pad 40 to move closer to the arm 51 (upward) while increasing the deflection (compression) of the coil spring 53.

[0030] An arm support section 54, which extends vertically, is connected to the opposite end of the arm 51. The arm support section 54 is moved vertically by a lifting drive unit. The lifting drive unit comprises a guide section 55, a ball screw 56, a motor 57, and an encoder 58.

[0031] The guided portion 541 of the arm support portion 54 is supported so as to be movable in the vertical direction with respect to the guide portion 55 which extends in the vertical direction. The threaded portion 542 of the arm support portion 54 is screwed onto a ball screw 56 which extends in the vertical direction. The ball screw 56 rotates when driven by a motor 57 connected to one end of the ball screw 56. When the ball screw 56 rotates and force is applied to the threaded portion 542, the arm support portion 54 moves vertically along the guide portion 55.

[0032] The driving direction and amount of the motor 57 are detected via the encoder 58. The detection signal from the encoder 58 is input to the control unit 80.

[0033] A ring nozzle 60 is provided on the outer periphery of the retaining pad 40. The ring nozzle 60 supplies water in a ring shape to the outer periphery of the retaining pad 40. As shown in Figures 5 and 6, the ring nozzle 60 comprises an annular housing 61, an annular supply port 62 opening on the lower side of the housing 61, and an annular supply passage 63 formed inside the housing 61 and communicating with the supply port 62. A portion of the supply passage 63 is a communication section 631 that communicates with the upper side of the housing 61, and the communication section 631 is connected to a connection section 64. The communication section 631 is provided only at specific locations in the circumferential direction, and in other parts, the supply passage 63 does not communicate with the upper side of the housing 61. The connection section 64 is connected to a water supply source 65 via an on / off valve 66.

[0034] A plate-shaped ring-shaped elastic plate material 70 is further provided on the outer edge of the retaining pad 40. The ring-shaped elastic plate material 70 is positioned so as to be sandwiched between the suction plate 41 and the ring nozzle 60 in the radial direction of the retaining pad 40. In other words, the ring nozzle 60 is positioned outside the ring-shaped elastic plate material 70 in the horizontal direction.

[0035] The detailed structure of the ring elastic plate material 70 and its surroundings will be described primarily with reference to Figures 5 and 6. Unless otherwise specified, the cross-sectional structure shown in Figures 5 and 6 is assumed to be continuous throughout the entire circumferential direction of the retaining pad 40.

[0036] The suction plate 41 has a cylindrical outer periphery 411 that surrounds the outer periphery of the recess 42, and an outward projection 412 that protrudes outward is provided at the lower end of the outer periphery 411. The upper surface of the outward projection 412 is a tapered surface 413 that slopes downward as it moves towards the outer periphery. In other words, the tapered surface 413 has a shape like the side of a truncated cone with a vertical axis passing through the center of the retaining pad 40.

[0037] An annular recess 414 is formed on the upper surface near the outer periphery of the suction plate 41, including the outer peripheral portion 411, and is lower than the upper surface of the suction plate 41. The annular recess 414 is a recess that is continuous in the circumferential direction.

[0038] The housing 61 of the ring nozzle 60 has an annular outer periphery 611 that surrounds the outside of the outer periphery 411 of the suction plate 41, and an inward projection 612 that protrudes inward from the upper end of the outer periphery 611. The inward projection 612 is formed continuously in the circumferential direction. The supply port 62 and supply passage 63 described above are formed in the outer periphery 611. The supply port 62 opens on the lower side of the outer periphery 611. As described above, the communication portion 631 and connection portion 64 are provided only at specific locations in the circumferential direction.

[0039] The inward projection 612 is supported so as to fit into the annular recess 414 from above, thereby determining the position of the housing 61 relative to the suction plate 41. In this state, there is a housing portion S, which is a radial gap of the retaining pad 40, between the outer periphery 411 of the suction plate 41 and the outer periphery 611 of the housing 61. The housing portion S is an annular space that is continuous in the circumferential direction, with the upper end of the housing portion S being closed by the inward projection 612 of the ring nozzle 60 and the lower end of the housing portion S being open. The ring elastic plate material 70 is supported inside this housing portion S.

[0040] The ring elastic plate material 70 is made of a material that is elastically deformable and non-permeable to water. Specifically, the ring elastic plate material 70 is made of rubber or the like. The ring elastic plate material 70 comprises a cylindrical main body portion 71 that fits into the housing portion S, and a lip portion 72 provided on the lower end side of the main body portion 71. Both the main body portion 71 and the lip portion 72 are formed continuously in the circumferential direction.

[0041] The main body portion 71 has dimensions that allow it to be held within the housing portion S while being compressed, and the force attempting to restore it from compression causes it to adhere tightly to the inner surface of the housing portion S. As a result, the ring elastic plate material 70 is held stably without falling out of the housing portion S.

[0042] The lip portion 72 protrudes from the inner end of the main body portion 71 toward the outer circumference, and has a shape that curves downward as it extends toward the outer circumference. In other words, the lip portion 72 is arranged in a ring shape that widens toward the outer edge of the suction plate 41. Furthermore, the thickness of the lip portion 72 decreases as it moves from the base end that connects to the main body portion 71 toward the outer circumference (tip end). A V-shaped groove portion 73 is formed between the main body portion 71 and the lip portion 72, and the base end of the lip portion 72 connects to the main body portion 71 in the narrow area on the inner circumference side of the groove portion 73.

[0043] This structure makes the lip portion 72 more flexible and elastically deformable than the main body portion 71. In particular, the lip portion 72 is easily deformed in a way that changes the cantilevered tip in the vertical direction. On the other hand, the main body portion 71 has a larger wall thickness than the lip portion 72 and is less prone to excessive deformation, so it can be stably fitted and supported in the housing portion S. Furthermore, since most of the space between the main body portion 71 and the lip portion 72 is separated by the groove portion 73, both the stability of support in the main body portion 71 and the ease of deformation of the lip portion 72 are achieved.

[0044] The base end of the lip portion 72 is supported along the tapered surface 413 of the outward projection 412. By extending along the inclination direction of the tapered surface 413, the lip portion 72 has a stable, flared shape with little variation in vertical position throughout its entire circumferential direction.

[0045] As shown in Figure 5, in the initial state when the lip portion 72 is not deformed by external force, the area near the tip of the lip portion 72 is located below the suction surface 44 of the holding pad 40. Here, the amount of downward protrusion of the lip portion 72 relative to the suction surface 44 is set to about half the maximum depth of the irregularities on the upper surface of the workpiece W (for example, the irregularities of grinding marks by the grinding mechanism 3). Also, the area near the tip of the lip portion 72 is located below the supply port 62.

[0046] The transport of the workpiece W in the transport device 4 of the grinding apparatus 1 with the above configuration will now be explained. The position where the workpiece W is held on the holding surface 23 of the holding table 2 is the first position of the workpiece W, and the position away from the holding surface 23 of the holding table 2 is the second position of the workpiece W.

[0047] When grinding the workpiece W using the grinding mechanism 3, the on / off valve 251 is opened, the suction source 25 communicates with the flow path 24, and a suction force acts on the holding surface 23 of the holding table 2. This suction force causes the workpiece W to be held in place by suction on the holding surface 23 (see Figure 1). In other words, the workpiece W is held in the first position.

[0048] Once the grinding of the workpiece W by the grinding mechanism 3 is complete, the holding pad 40 is positioned above the holding table 2, as shown in Figure 2. Then, the motor 57 of the moving mechanism 50 is driven to rotate the ball screw 56, moving the arm 51 and the arm support 54 downward. This movement causes the holding pad 40 to descend toward the upper surface of the workpiece W (workpiece W in the first position) on the holding table 2.

[0049] As the holding pad 40 descends, the suction surface 44 of the holding pad 40 comes into contact with the upper surface of the workpiece W, as shown in Figure 3. The motor 57 is stopped when the suction surface 44 comes into contact with the upper surface of the workpiece W. The amount of movement of the holding pad 40 until the suction surface 44 comes into contact with the upper surface of the workpiece W is managed by detecting and controlling the amount of drive of the motor 57 based on a signal from the encoder 58.

[0050] Alternatively, from the moment the suction surface 44 contacts the upper surface of the workpiece W (when the holding pad 40 stops moving downwards), the arm 51 and arm support 54 may be moved further downwards by the moving mechanism 50, thereby compressing the coil spring 53 and pressing the workpiece W against the holding surface 23 of the holding table 2 with the holding pad 40. Figure 3 shows this state, where the arm 51 moves downward along the slide axis 52, reducing the gap between the lower surface of the arm 51 and the upper surface of the suction plate 41, and compressing the coil spring 53.

[0051] As shown in Figure 5, before the suction surface 44 of the holding pad 40 contacts the upper surface of the workpiece W, the tip of the lip portion 72 of the ring elastic plate material 70 is located below the suction surface 44. As shown in Figure 6, when the suction surface 44 of the holding pad 40 contacts the upper surface of the workpiece W, the tip of the lip portion 72 contacts and presses against the upper surface of the outer circumference of the workpiece W. This pressing causes the lip portion 72 to elastically deform by pushing its tip slightly upward, and the lip portion 72 comes into close contact with the upper surface of the workpiece W.

[0052] When the suction surface 44 of the retaining pad 40 contacts the upper surface of the workpiece W and the descent of the retaining pad 40 stops, the water supply source 65 is activated and the on / off valve 66 is opened, supplying water to the supply passage 63 of the ring nozzle 60. As shown in Figure 6, water L is then discharged from the annular supply port 62 and supplied to the outer circumference of the retaining pad 40.

[0053] Furthermore, when the suction surface 44 of the holding pad 40 comes into contact with the upper surface of the workpiece W and the downward movement of the holding pad 40 stops, the suction source 46 is activated and the on / off valve 461 is opened. As a result, air is drawn in from the holding part 43 side through the flow path 45, a suction force acts on the suction surface 44, and the upper surface of the workpiece W is drawn towards the holding pad 40 side.

[0054] The operations described above—bringing the suction surface 44 of the holding pad 40 into contact with the upper surface of the workpiece W and pressing the lip portion 72 of the ring elastic plate material 70 against the upper surface of the outer circumference of the workpiece W, supplying water L from the ring nozzle 60, and connecting the suction surface 44 to the suction source 46 to hold the workpiece W in suction with the suction surface 44—are controlled by the holding control unit 81 (Figure 7), which is a functional block of the control unit 80.

[0055] Once the workpiece W is held by the holding pad 40 under the control of the holding control unit 81, the on / off valve 251 is closed, disconnecting it from the suction source 25, and preventing any suction force from acting on the workpiece W from the holding surface 23 of the holding table 2.

[0056] Then, the air supply source 26 is activated and the on / off valve 261 is opened to supply air from the holding surface 23 of the holding table 2 toward the underside of the workpiece W.

[0057] Alternatively, the water supply source 27 may be activated and the on / off valve 271 opened to supply water from the holding surface 23 of the holding table 2 toward the underside of the workpiece W. This causes the pressure of the mixed fluid of air and water from the holding surface 23 to push up the holding pad 40 that holds the workpiece W, separating the workpiece W from the holding surface 23.

[0058] When air or water is ejected from the holding surface 23 toward the lower surface of the workpiece W, grinding debris that had entered the holding part 22 during the previous grinding process is ejected from the holding surface 23 along with the air or water. At this time, the upper surface of the workpiece W is sealed by the lip portion 72 of the ring elastic plate material 70 and the water supplied from the ring nozzle 60, so that grinding debris ejected from the holding part 22 does not adhere to the upper surface of the workpiece W.

[0059] Next, as shown in Figure 4, the motor 57 of the moving mechanism 50 is driven to rotate the ball screw 56, moving the arm 51 and the arm support 54 upward. This movement causes the holding pad 40, which is holding the workpiece W by suction, to rise, and the workpiece W is separated from the mixed fluid on the holding surface 23 of the holding table 2.

[0060] Next, once the workpiece W is separated from the mixed fluid, the operation of the water supply source 65 is stopped and the on / off valve 66 is closed, ending the supply of water to the supply passage 63 of the ring nozzle 60. This stops the water supply from the supply port 62 of the ring nozzle 60. This stopping of the water supply from the ring nozzle 60 is controlled by the water supply control unit 82 (Figure 7), which is a functional block of the control unit 80.

[0061] The conveying device 4 moves the holding pad 40, which is holding the workpiece W by suction, above the holding table 2, and then moves the holding pad 40 to the area of ​​the spinner cleaning unit 6 by rotating the moving mechanism 50. This movement is performed with the water supply from the ring nozzle 60 stopped.

[0062] When the holding pad 40 reaches the area of ​​the spinner cleaning unit 6, the motor 57 of the moving mechanism 50 is driven to rotate the ball screw 56, moving the arm 51 and the arm support part 54 downward. Then, the lower surface of the workpiece W, which is held by suction of the holding pad 40, is supported on the spinner table (not shown) of the spinner cleaning unit 6.

[0063] Once the transport of the workpiece W by the transport device 4 is complete and it is time to release the suction holding of the workpiece W by the holding pad 40, the operation of the suction source 46 is stopped or the on / off valve 461 is closed so that no suction force acts on the suction surface 44. Next, the air supply source 47 is activated and the on / off valve 471 is opened to supply air from the suction surface 44 toward the upper surface of the workpiece W. As a result, the air pressure from the suction surface 44 makes it easier for the workpiece W to separate from the holding pad 40.

[0064] In this way, the workpiece W after grinding is moved from a first position to a second position on the holding table 2. The second position is, for example, the spinner cleaning unit 6. Note that the second position may be other than the spinner cleaning unit 6. This movement of the workpiece W from the first position to the second position is controlled by the movement control unit 83 (Figure 7), which is a functional block of the control unit 80.

[0065] As described above, the transport device 4 moves the workpiece W from a first position on the holding table 2 to a second position away from the holding table 2 and then transports it out, through the control of the holding control unit 81, the water supply control unit 82, and the movement control unit 83 of the control unit 80. Note that the holding control unit 81, the water supply control unit 82, and the movement control unit 83 in the control unit 80 are conceptual functional blocks corresponding to each process in transporting the workpiece W, and this does not mean that each control unit 81, 82, and 83 exists structurally separately. The functions of each control unit 81, 82, and 83 are realized by the operation of the processor, memory, etc. that make up the control unit 80.

[0066] In the conveying of the workpiece W by the conveying device 4 described above, the lip portion 72 of the ring elastic plate material 70 contacts the upper surface of the outer circumference of the workpiece W, making it difficult for air to leak between the workpiece W and the suction surface 44, thereby suppressing leakage of suction force acting on the workpiece W from the holding pad 40. In particular, even if there are irregularities on the upper surface of the workpiece W, the elastically deformable lip portion 72 deforms to conform to the irregularities on the outer circumference of the workpiece W, thus increasing the effect of suppressing suction force leakage caused by the irregularities.

[0067] The lip portion 72 of the ring elastic plate material 70 protrudes downward from the suction surface 44 when the holding pad 40 is not yet holding the workpiece W (when the suction surface 44 is not in contact with the workpiece W). Therefore, when the workpiece W is held by the suction surface 44, the lip portion 72 can reliably make contact with the entire outer circumference of the workpiece W.

[0068] Furthermore, the amount of downward protrusion of the lip portion 72 relative to the suction surface 44 is set to approximately half the maximum depth of the irregularities on the upper surface of the workpiece W formed by grinding or the like. This has the advantage that when the holding pad 40 holds the workpiece W, the force exerted by the ring elastic plate material 70 on the workpiece W is kept small, and excessive stress is not placed on the workpiece W. Therefore, localized loads are less likely to be applied to the workpiece W that has been thinned by grinding, and even thin workpieces W can be held stably.

[0069] By providing a ring-shaped elastic plate material 70 on the outer edge of the suction plate 41, a lip portion 72 that contacts the workpiece W with appropriate force can be formed. Unlike this embodiment, if the elastic portion for preventing leaks is provided in a form that protrudes on the suction surface 44 (inward from the outer edge of the suction plate 41), the elastic portion may press the workpiece W too hard, or a gap may easily form between the suction surface 44 and the upper surface of the workpiece W, which may damage the workpiece W or reduce the suction holding performance of the workpiece W.

[0070] The fact that the base end of the lip portion 72 is supported on the tapered surface 413 of the outward projection 412 of the suction plate 41 also contributes to preventing the lip portion 72 from excessively pushing down the workpiece W.

[0071] Furthermore, when the holding pad 40 holds the workpiece W, water is supplied from a ring nozzle 60 located near the ring elastic plate material 70, causing a small amount of water to penetrate the inside of the lip portion 72, forming a water seal at the part of the lip portion 72 that contacts the workpiece W. This water seal further improves the effect of suppressing suction force leakage in the holding pad 40.

[0072] Water is supplied from the ring nozzle 60 only when the holding pad 40 is holding the workpiece W, and the water supply from the ring nozzle 60 is stopped when the workpiece W is moved from the first position to the second position. Because the water seal formed around the lip portion 72 of the ring elastic plate material 70 by the water supply from the ring nozzle 60 that was performed earlier continues to suppress the leakage of suction force, the holding pad 40 can reliably continue to hold the workpiece W even without the continuous supply of water from the ring nozzle 60 when moving from the first position to the second position. Furthermore, a water-saving effect is obtained by stopping the water supply from the ring nozzle 60 during transport.

[0073] The above describes the case where the ground workpiece W is removed from the holding table 2, but the conveying device 4 and holding pad 40 of this embodiment are also useful when loading the workpiece W into the holding table 2.

[0074] For example, a known method involves irradiating an ingot such as silicon carbide (SiC) with a laser to form a laser-processed layer parallel to the end face, and then peeling it off along the laser-processed layer to form a wafer. In this case, since the wafer has irregularities in the peeled portion along the laser-processed layer, using the transport device 4 and holding pad 40 of this embodiment when loading such a wafer into a grinding machine provides superior holding performance compared to existing holding pads.

[0075] The conveying device 4 and holding pad 40 described above are examples, and the shape and structure of the details are not limited thereto. For example, in this embodiment, the ring elastic plate material 70 separates the main body portion 71 and the lip portion 72 with a groove portion 73, thereby providing stable support by increasing the thickness of the main body portion 71, while also making the lip portion 72 more easily deformable. In contrast, if the thickness of the portion corresponding to the main body portion 71 is small, or if the thickness of the portion corresponding to the main body portion 71 is stepped, it is also possible to configure the lip portion to protrude directly from the lower end surface of the main body portion without providing a shape like the groove portion 73.

[0076] The holding pad and conveying device of the present invention are not limited to application to grinding machines, but can also be applied to processing machines other than grinding machines. Specifically, the invention may consist of a holding pad that suction-holds a workpiece and a conveying device that moves the holding pad to transport the workpiece.

[0077] Furthermore, the embodiments of the present invention are not limited to those described above, and may be modified, substituted, or transformed in various ways without departing from the spirit of the technical idea of ​​the present invention. Moreover, if the technical idea of ​​the present invention can be realized in a different way by advances in the art or by other derived arts, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial applicability]

[0078] As described above, the holding pad and conveying device of the present invention have the effect of having excellent holding properties for workpieces with uneven surfaces on the upper surface or workpieces with a small thickness, and are particularly useful in processing equipment such as grinding machines that often handle such workpieces. [Explanation of Symbols]

[0079] 1: Grinding device 2: Holding Table 3: Grinding mechanism 4: Conveying device 5: Work Supply Department 6: Spinner cleaning unit 20:Frame body 22: Holding part 23: Holding surface 24: Flow path 25: Suction source 26: Air supply source 27: Water supply source 30: Spindle 32: Grinding Wheel 33: Sharpening stone 34: Spindle drive motor 35: Lifting mechanism 40: Retaining pad 41: Suction plate 43: Holding part 44: Suction surface 45: Flow path (suction path) 46: Suction source 47: Air supply source 50: Movement mechanism 51: Arm 54: Arm support section 55: Guide section 56: Ball screw 57: Motor 60: Ring nozzle 61: Housing 62: Supply port 63: Supply route 65: Water supply source 66: Shut-off valve 70: Ring elastic plate material 71: Main body 72: Lip part 73: Groove 80: Control Unit 81: Holding control unit 82: Water supply control unit 83: Movement Control Unit W: Work

Claims

1. A retaining pad that holds the upper surface of a workpiece by suction, The device comprises a suction plate having a suction surface for holding the upper surface of a workpiece by suction, a suction passage formed inside the suction plate and connecting the suction surface to a suction source, a plate-shaped ring elastic plate material arranged in a ring-like, widening shape on the outer edge of the suction plate with its lower end in contact with the upper surface of the workpiece, and a ring nozzle arranged horizontally outside the ring elastic plate material to supply water in a ring shape. The ring elastic plate material comprises a cylindrical main body and a lip portion provided on the lower end side of the main body, the lower end of which contacts the upper surface of the workpiece. The ring nozzle is a retaining pad that supplies water to the lower end of the lip portion.

2. The retaining pad according to claim 1, wherein the suction plate has a ring-shaped outward projection that supports the lip portion, with the lower part of the outer circumference protruding outwards and the upper surface becoming lower as it moves outwards.

3. A conveying device that attaches a holding pad according to claim 1 or 2 and conveys a workpiece from a first position to a second position, The device comprises a moving mechanism for moving the retaining pad from the first position to the second position, and a control unit. The control unit includes a holding control unit which brings the suction surface into contact with the upper surface of the workpiece at the first position, presses the lower end of the lip portion of the ring elastic plate material against the upper surface of the outer circumference of the workpiece, supplies water from the ring nozzle to the lower end of the lip portion, connects the suction surface to a suction source, and holds the workpiece by suction with the suction surface, A conveying device comprising: a water supply control unit that stops the supply of water from the ring nozzle to the lower end of the lip portion before moving the retaining pad from the first position to the second position; and a movement control unit that moves the retaining pad from the first position to the second position.

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