Chuck table and half-cutting method

Abstract

To provide a chuck table capable of suction-holding the whole undersurface of a warped workpiece.SOLUTION: Chuck tables (16 and 80) for suction-holding a plate-like workpiece (11) by a holding surface comprise: a base (51) which has a top surface provided with the holding surface; a plurality of suction holes (60) which are arranged on the holding surface and which can communicate with a suction source (63) through an undersurface; and elastic elastomer members (70 and 82) which are arranged with a predetermined thickness on the whole holding surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a chuck table for holding a plate-shaped workpiece, and a half-cutting method for half-cutting a plate-shaped workpiece. [Background technology]

[0002] As disclosed in Patent Documents 1 and 2, when cutting a plate-shaped workpiece, the underside of the workpiece is held by suction on the holding surface of a chuck table, and a cutting blade is cut into the workpiece from the top side to form a cutting groove (machined groove). In cutting, for example, a half cut is performed to form a cutting groove that is less deep than the thickness of the workpiece. However, if the entire underside of the workpiece is not in contact with the holding surface of the chuck table due to warping of the workpiece, the workpiece may not be sufficiently held by suction on the holding surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2015-082627 [Patent Document 2] Japanese Patent Publication No. 2020-062722 Summary of the Invention [Problem to be solved by the invention]

[0004] If the workpiece cannot be sufficiently sucked and held on the holding surface of the chuck table, the workpiece may shift during cutting, which can cause problems such as damage to the cutting blade.

[0005] Therefore, there is a problem to be solved in a processing device that performs processing such as cutting on a workpiece, namely, to provide a chuck table that can suction and hold the entire lower surface of a warped workpiece.

[0006] Furthermore, when cutting a warped workpiece, if the cutting is performed without taking into account the effect of the warp of the workpiece, there is a risk that the depth of the cut grooves formed by the cutting will vary.

[0007] Therefore, when cutting a warped workpiece, a cutting device has to form a cutting groove with high precision that is less than the thickness of the workpiece. [Means for solving the problem]

[0008] One aspect of the present invention is a chuck table that suction-holds a plate-shaped workpiece with a holding surface, and comprises a base having the holding surface on its upper surface, a plurality of suction holes arranged on the holding surface that penetrate to the lower surface and can communicate with a suction source, and an elastomer elastic member arranged to a predetermined thickness over the entire holding surface.

[0009] The elastic member preferably has a dynamic viscoelasticity of 0.1 tan δ or more and 0.4 tan δ or less at a temperature of 20°C to 30°C.

[0010] The elastic member is preferably made of, for example, a thermoplastic elastomer or a foamed elastomer.

[0011] This is particularly useful when the plate-like workpiece has bumps on one surface and is held by contacting the bumps with the elastic member.

[0012] One aspect of the present invention is a half-cut method for forming a cutting groove in a plate-shaped workpiece held on the above-mentioned chuck table with a cutting blade, the cutting groove having a depth less than the thickness of the plate-shaped workpiece, and includes the following steps: a holding step for suction-holding the plate-shaped workpiece on the chuck table; a work top surface height measuring step for moving the plate-shaped workpiece held in the holding step in a cutting feed direction and measuring the top surface height of the plate-shaped workpiece at multiple positions in the cutting feed direction relative to the cutting blade; and a cutting step for forming the cutting groove by raising and lowering the cutting blade while moving the plate-shaped workpiece in the cutting feed direction based on the multiple top surface heights measured in the top surface height measuring step so that the cutting groove is of a predetermined depth from the top surface. [Effects of the Invention]

[0013] According to the chuck table of the present invention, the elastic member made of elastomer is disposed on the entire holding surface of the base, so that the entire lower surface of a warped workpiece can be sucked and held.

[0014] According to the half-cut method of the present invention, the entire underside of a warped workpiece is suction-held by a chuck table, and the cutting process is performed by raising and lowering the cutting blade based on the top surface heights of multiple positions measured in the top surface height measurement process of the workpiece, thereby making it possible to form cutting grooves in the warped workpiece with a depth that is less than the thickness of the workpiece with high precision. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a cutting device equipped with a chuck table. [Figure 2] FIG. [Figure 3] FIG. 2 is a cross-sectional view of the chuck table. [Figure 4] 1A and 1B are diagrams showing the structure of a workpiece and the state of warping. [Figure 5] 1A and 1B are diagrams showing the structure of a workpiece and the state of warping. [Figure 6] 10A and 10B are cross-sectional views showing an upper surface height measuring step in the half-cut method. [Figure 7] 10A to 10C are cross-sectional views showing a cutting step in a half-cut method. [Figure 8] FIG. 10 is a perspective view of a chuck table according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0016] The chuck table and half-cutting method according to this embodiment will be described below with reference to the accompanying drawings. This embodiment is applied to a chuck table 16 provided in a cutting device 10 shown in Fig. 1. The X-axis and Y-axis directions of the cutting device 10 are horizontal directions, and are perpendicular to each other. The Z-axis direction is the up-down direction, with the +Z direction being upward and the -Z direction being downward.

[0017] The cutting device 10 is a processing device that cuts a plate-shaped workpiece 11 (plate-shaped workpiece) that is a workpiece. The cutting device 10 has a pair (two) cutting units 12 arranged opposite each other in the Y-axis direction, and cuts the workpiece 11 using each cutting unit 12. The number of cutting units is not limited to two, and may be one or three or more cutting units.

[0018] 6 and 7, the cutting unit 12 has an annular cutting blade 38 attached to the tip side of a spindle 37, which is a rotation shaft extending in the Y-axis direction. The spindle 37 is rotated by a spindle motor (not shown), and the cutting blade 38, which rotates together with the spindle 37, cuts into the workpiece 11 to perform cutting processing.

[0019] The cutting device 10 is controlled by a control unit 90. The control unit 90 has a processing unit 91 (processor) that generates signals for controlling each part of the cutting device 10, and a storage unit 92 (memory) that stores various information used by the processing unit 91. The processing unit 91 controls the operation of each part of the cutting device 10, which will be described later, by reading and executing a program stored in the storage unit 92. Therefore, when describing the operation of each part of the cutting device 10, unless a controlling entity is specified, it is assumed that the operation is performed under the control of the control unit 90.

[0020] An opening 14 extending in the X-axis direction is formed on a base 13 of the cutting device 10. A movable plate 15 is supported inside the opening 14, and a chuck table 16 is provided on the movable plate 15. Bellows 17 are connected to both sides of the movable plate 15 in the X-axis direction, and the opening 14 is covered by the movable plate 15 and the bellows 17.

[0021] The chuck table 16 is a table that holds the workpiece 11 by suction when the workpiece 11 is cut using the cutting unit 12. The chuck table 16 will be described in detail later.

[0022] The movable plate 15 and the chuck table 16 are moved in the X-axis direction by a table feed mechanism 18 provided inside the opening 14 below the movable plate 15. The X-axis direction is a cutting feed direction in which, during cutting, the workpiece 11 held on the chuck table 16 is cut while being moved relative to the cutting unit 12. The table feed mechanism 18 includes a guide rail and a ball screw, each of which extends in the X-axis direction, and a base (not shown) that supports the movable plate 15 and the chuck table 16 is supported by the guide rail so as to be movable in the X-axis direction. A ball screw is threadedly engaged with the base, and when the ball screw is rotated by a motor, the base moves in the X-axis direction.

[0023] Furthermore, the chuck table 16 can be rotated by a table rotation mechanism 19 around an axis that faces the Z-axis direction relative to the base portion.

[0024] The chuck table 16 is moved in the X-axis direction by a table feed mechanism 18, and can be positioned in a mounting / dismounting area on the +X direction side and a processing area on the -X direction side. In the mounting / dismounting area, the workpiece 11 is mounted on or removed from the chuck table 16. In the processing area, the chuck table 16 is positioned below the cutting unit 12, and the workpiece 11 held on the chuck table 16 can be cut by the cutting unit 12.

[0025] A gate-shaped column 20 is provided on the base 13, spanning the opening 14 in the Y-axis direction. A pair of guide rails 21 extending in the Y-axis direction are attached to the side surface of the column 20 facing the +X direction. A ball screw 22 and a ball screw 23, each extending in the Y-axis direction, are disposed between the pair of guide rails 21. The ball screw 22 is rotationally driven by a motor 24, and the ball screw 23 is rotationally driven by a motor (not shown).

[0026] Y-axis moving table 26 and Y-axis moving table 27 are supported movably in the Y-axis direction via a pair of guide rails 21. A ball screw 22 is threadedly engaged with a screw hole (not shown) provided in Y-axis moving table 26, and when ball screw 22 rotates, Y-axis moving table 26 moves in the Y-axis direction. A ball screw 23 is threadedly engaged with a screw hole (not shown) provided in Y-axis moving table 27, and when ball screw 23 rotates, Y-axis moving table 27 moves in the Y-axis direction.

[0027] A pair of guide rails 28 extending in the Z-axis direction are attached to the +X-direction side surface of the Y-axis moving table 26. A ball screw 29 extending in the Z-axis direction is disposed between the pair of guide rails 28. The ball screw 29 is rotationally driven by a motor 30. A Z-axis moving table 31 is supported via the pair of guide rails 28 so as to be movable in the Z-axis direction. The ball screw 29 is threadedly engaged with a screw hole (not shown) provided in the Z-axis moving table 31, and when the ball screw 29 rotates, the Z-axis moving table 31 moves in the Z-axis direction.

[0028] A pair of guide rails 32 extending in the Z-axis direction are attached to the +X-direction side surface of the Y-axis moving table 27. A ball screw 33 extending in the Z-axis direction is disposed between the pair of guide rails 32. The ball screw 33 is rotationally driven by a motor 34. A Z-axis moving table 35 is supported via the pair of guide rails 32 so as to be movable in the Z-axis direction. The ball screw 33 is threadedly engaged with a screw hole (not shown) provided in the Z-axis moving table 35, and when the ball screw 33 rotates, the Z-axis moving table 35 moves in the Z-axis direction.

[0029] One cutting unit 12 is supported at the lower end of the Z-axis moving table 31, and the other cutting unit 12 is supported at the lower end of the Z-axis moving table 35. By moving the Y-axis moving table 26 in the Y-axis direction, the position of one cutting unit 12 changes in the Y-axis direction, and by moving the Z-axis moving table 31 in the Z-axis direction, the position of one cutting unit 12 changes in the Z-axis direction. By moving the Y-axis moving table 27 in the Y-axis direction, the position of the other cutting unit 12 changes in the Y-axis direction, and by moving the Z-axis moving table 35 in the Z-axis direction, the position of the other cutting unit 12 changes in the Z-axis direction. In this way, the pair of cutting units 12 can be moved individually in the Y-axis and Z-axis directions.

[0030] An upper surface height measuring device 36 is provided near one of the cutting units 12 located on the +Y direction side. The upper surface height measuring device 36 moves in the Y-axis direction and the Z-axis direction together with this one of the cutting units 12. Note that the upper surface height measuring device 36 may be supported so as to move independently of the cutting unit 12.

[0031] The top surface height measuring device 36 is a height sensor capable of non-contact measurement of the height of the workpiece 11 held on the chuck table 16. One example of a height sensor is equipped with an imaging unit capable of imaging downward, and measures the height position of the workpiece 11 by imaging the workpiece 11 with the imaging unit and focusing the imaging unit using a contrast detection method or the like. Another example of a height sensor is one that projects measurement light toward the workpiece 11, receives the light reflected from the top surface of the workpiece 11, and measures the height position of the workpiece 11 based on the time between light projection and reception. Another example of a height sensor is one that emits ultrasonic waves toward the workpiece 11, receives the light reflected from the top surface of the workpiece 11, and measures the height position of the workpiece 11 based on the time between emission and reception.

[0032] The workpiece 11 to be cut by the cutting device 10 is, for example, a package substrate. The package substrate is formed by mounting a device chip in each of a plurality of device regions of a mounting substrate and sealing the device chip with a sealing material.

[0033] As shown in Figures 4 and 5, the workpiece 11 has a substrate 40 that is rectangular in plan view, and the substrate 40 has a plurality of device regions that are partitioned by grid-like planned division lines 41. On one surface of the substrate 40, a plurality of bumps 42, which are metal protruding electrodes, are provided at positions corresponding to each of the plurality of device regions. On the other surface of the substrate 40, a device chip 43 is disposed in each of the plurality of device regions. The device chips 43 in each device region are connected to the bumps 42 in the same device region. The plurality of device chips 43 are covered and sealed with a resin layer 44 (mold resin).

[0034] A workpiece 11 having such a configuration is prone to warping in the device region where the device chips 43 are formed. Fig. 4 shows, as an example of the workpiece 11, a workpiece 11 having a configuration in which the device region is provided continuously over the entire surface except for the outer periphery. Fig. 5 shows, as a different example of the workpiece 11, a workpiece 11 having a configuration in which the device region is provided in two separate island-like portions separated in the longitudinal direction of the substrate 40.

[0035] 4 and 5 show the workpiece 11 as seen obliquely and from the side, respectively, and the state of warpage of the workpiece 11 as seen from the side is indicated by a curve P. Note that the illustrated curve P exaggerates the magnitude of the warpage and differs from the actual magnitude of the warpage of the workpiece 11. As can be seen from FIGS. 4 and 5, the workpiece 11 is warped so that one surface on which the bumps 42 are provided is convex and the other surface on which the device chip 43 is provided is concave. The shape of the warpage of the workpiece 11 differs depending on the arrangement of the device region on the workpiece 11.

[0036] The workpiece 11 is placed with one surface on which the bumps 42 are provided on the holding surface of the chuck table 16, and is suction-held on the chuck table 16. In other words, the workpiece 11 is suction-held on the chuck table 16 with the one surface on which the bumps 42 are provided facing downward.

[0037] When holding the workpiece 11 on the holding surface of a conventional chuck table different from the chuck table 16 of this embodiment, if the entire underside of the workpiece 11 does not contact the holding surface of the chuck table due to warpage of the workpiece 11, the workpiece 11 may not be sufficiently suction-held on the holding surface. In particular, in the case of a workpiece 11 with warpage as shown in FIGS. 4 and 5, the outer periphery of the workpiece 11 does not adhere to the holding surface of the chuck table and becomes raised, which is likely to cause a leakage of suction force around the outer periphery of the workpiece 11. Furthermore, as shown in FIGS. 4 and 5, the workpiece 11 may have various types of warpage, making it difficult to prepare a chuck table with a holding surface shape that can accommodate various types of warpage. Furthermore, the uneven shape of the underside of the workpiece 11, which has bumps 42, also causes the entire underside of the workpiece 11 not to contact the holding surface of the chuck table.

[0038] If the entire underside of the workpiece 11 cannot be suction-held on the holding surface of the chuck table, the workpiece 11 will shift position during cutting, which will result in problems such as not being able to perform high-precision cutting on the workpiece 11, or the cutting blade 38 of the cutting unit 12 being subjected to excessive load due to vibration of the workpiece 11, causing it to break.

[0039] To prevent such problems, the chuck table 16 of this embodiment is configured to be able to suction and hold the entire lower surface of the warped workpiece 11. The chuck table 16 will be described in detail with reference to Figs. 2 and 3.

[0040] The chuck table 16 includes a lower pedestal 50 and a base 51 that is detachable from the upper part of the lower pedestal 50. The lower pedestal 50 is attached to a rotating plate 52 that constitutes the table rotation mechanism 19. When the table rotation mechanism 19 rotates the rotating plate 52, the chuck table 16 rotates together with the rotating plate 52.

[0041] The lower base 50 is a plate-like member that is approximately rectangular in plan view. The lower base 50 is made of a metal such as stainless steel. Four screw holes 53 are formed near the four corners of the lower base 50. A frame-shaped outer peripheral region 54 near the outer edge of the lower base 50 has no holes other than the screw holes 53, and the upper surface of the outer peripheral region 54 is flat except for the areas where the screw holes 53 are formed. A large number of suction holes 56 are formed at predetermined intervals in an inner region 55 that is surrounded by the outer peripheral region 54. As shown in FIG. 3 , each suction hole 56 opens to the upper surface of the lower base 50, and the lower ends of the suction holes 56 are connected to a suction path 62.

[0042] The outer peripheral region 54 and the inner region 55 conceptually represent the region where the suction holes 56 are provided and the region where they are not provided, and it is not essential to provide a clear boundary line between the outer peripheral region 54 and the inner region 55. However, in order to prevent air leakage between the suction holes 56 and the through holes 57 of the base 51 (described later), it is also possible to configure the inner region 55 to protrude upward relative to the outer peripheral region 54, thereby ensuring close contact between the inner region 55 and the base 51.

[0043] The base 51 is a plate-like member that is substantially rectangular in plan view and has substantially the same size as the lower pedestal 50. The base 51 is made of a metal such as stainless steel. Four through holes 57 are formed near the four corners of the base 51. The four through holes 57 are arranged in a positional relationship corresponding to the four screw holes 53 of the lower pedestal 50. A frame-shaped outer peripheral region 58 near the outer edge of the base 51 has no holes other than the through holes 57, and the upper surface of the outer peripheral region 58 is flat except for the areas where the through holes 57 are formed. The inner region surrounded by the outer peripheral region 58 is a holding surface region 59. A number of suction holes 60 are formed at predetermined intervals in the holding surface region 59 (see FIG. 3). The number of suction holes 60 are arranged in a positional relationship corresponding to the number of suction holes 56 of the lower pedestal 50. Each suction hole 60 penetrates the base 51 in the vertical direction (Z-axis direction) and opens to the upper and lower surfaces of the base 51.

[0044] When assembling the chuck table 16, the four screw holes 53 and the four through holes 57 are positioned to overlap, and the lower surface of the base 51 is placed on the upper surface of the lower pedestal 50. Fixing screws 61 are inserted into each of the through holes 57 and rotated, and the fixing screws 61 are screwed into each of the screw holes 53. When each fixing screw 61 is tightened with a predetermined torque, the base 51 is fixed to the lower pedestal 50. By rotating each fixing screw 61 in the direction opposite to the tightening direction, the fixing of the base 51 to the lower pedestal 50 can be released, and the base 51 can be removed.

[0045] As shown in Figure 3, when the base 51 is fixed to the lower base 50 using fixing screws 61, the multiple suction holes 60 formed in the base 51 are each connected to the multiple suction holes 60 formed in the lower base 50.

[0046] The chuck table 16 further has an elastomer elastic member 70 arranged to a predetermined thickness over the entire holding surface area 59 of the base 51. Therefore, the holding surface of the chuck table 16 is formed by the elastic member 70. The elastic member 70 has an area that is capable of holding the entire lower surface of the workpiece 11. A large number of suction holes 71 are formed in the elastic member 70 at predetermined intervals. The large number of suction holes 71 are arranged in a positional relationship that corresponds to the large number of suction holes 60 of the base 51.

[0047] 3, the plurality of suction holes 71 formed in the elastic member 70 each penetrate the elastic member 70 in the vertical direction (Z-axis direction) and open to the upper and lower surfaces of the elastic member 70. Each suction hole 71 communicates with a suction hole 60 in the base 51, and the suction hole 60 communicates with a suction hole 56 in the lower pedestal 50. Therefore, the lower pedestal 50, the base 51, and the elastic member 70 are stacked in a positional relationship such that each suction hole 56, suction hole 60, and suction hole 71 communicates with each other in the vertical direction.

[0048] 3, the multiple suction holes 56 are connected to a suction source 63 via a suction path 62. An on-off valve 64 is provided midway through the suction path 62, and operation of the on-off valve 64 can switch between an open state in which the suction holes 56, 60, and 71 are in communication with the suction source 63, and a closed state in which communication between the suction holes 56, 60, and 71 and the suction source 63 is blocked. When the on-off valve 64 is in the open state, operating the suction source 63 sucks air through the suction holes 56, 60, and 71, creating a negative pressure on the upper surface of the elastic member 70, and a suction force can be applied to the holding surface formed by the elastic member 70.

[0049] When the workpiece 11 is held on the chuck table 16, the on-off valve 64 is opened and the suction source 63 is operated to apply suction force to the upper surface of the elastic member 70, and the lower surface of the workpiece 11 is placed on the upper surface of the elastic member 70. Then, the lower surface of the workpiece 11 is held by suction in close contact with the elastic member 70. At this time, the multiple bumps 42 protruding from the lower surface of the workpiece 11 come into contact with the elastic member 70.

[0050] The elastic member 70 is formed from a low-resilience flexible material that has excellent shape-following ability to accommodate warping of the workpiece 11 and unevenness on the underside of the workpiece 11, and even when the workpiece 11 is warped or when unevenness such as bumps 42 exists on the underside of the workpiece 11, the elastic member 70 can be brought into close contact with the entire underside of the workpiece 11.

[0051] Specifically, it is desirable that the dynamic viscoelasticity of the elastic member 70 is 0.1 tan δ or more and 0.4 tan δ or less at a temperature between 20° C. and 30° C. The dynamic viscoelasticity is measured by applying periodic vibration or deformation to the material of the elastic member 70 and measuring the elasticity and viscosity as a function of temperature from the stress caused by the vibration or deformation.

[0052] As a result of the experiment, it was found that when the dynamic viscoelasticity of the elastic member 70 satisfied the above conditions, the elastic member 70 exhibited excellent shape conformability to the warpage of the workpiece 11, and the elastic member 70 could be brought into close contact with the entire underside of the warped workpiece 11. Furthermore, when the dynamic viscoelasticity of the elastic member 70 satisfied the above conditions, the elastic member 70 could be brought into close contact with the entire underside of the workpiece 11, which not only had warpage but also had bumps 42 on its underside. Conversely, it was found that when the dynamic viscoelasticity of the elastic member 70 was far outside the above condition range, there was a risk that the elastic member 70 would not be in close contact with part of the underside of the warped workpiece 11.

[0053] Furthermore, the thickness of the elastic member 70 is preferably in the range of 0.1 mm to 1 mm. Experimental results have shown that when the thickness of the elastic member 70 is in the above range, the elastic member 70 can be brought into close contact with the entire underside of the workpiece 11, even if the workpiece 11 has warpage or an uneven underside. If the thickness of the elastic member 70 is smaller than the above range, it becomes difficult to achieve shape conformability that adequately accommodates warpage of the workpiece 11 or the unevenness of the underside of the workpiece 11. If the thickness of the elastic member 70 is larger than the above range, the stability of the workpiece 11 may be reduced when the workpiece 11 is held by the chuck table 16, and it may become difficult to ensure the accuracy of the position and orientation of the workpiece 11.

[0054] The elastic member 70 of this embodiment is made of a thermoplastic elastomer. This thermoplastic elastomer is in a liquid or paste form at room temperature and hardens while retaining its flexibility when heated to a predetermined temperature. When forming the elastic member 70 on the chuck table 16, the liquid or paste thermoplastic elastomer is applied to the holding surface region 59 of the base 51, and after application, the thermoplastic elastomer is heated to a predetermined hardening temperature to form the elastic member 70 that satisfies the dynamic viscoelasticity conditions described above.

[0055] Before the thermoplastic elastomer applied to the base 51 is heated and cured, the on-off valve 64 is opened and the suction source 63 is operated to perform suction. This suction causes the thermoplastic elastomer to be sucked into the areas corresponding to the numerous suction holes 56 and 60, forming numerous suction holes 71 in the areas where the thermoplastic elastomer has been applied. The thermoplastic elastomer is then heated to complete the elastic member 70 having numerous suction holes 71. This manufacturing method makes it possible to easily and accurately form numerous suction holes 71 at positions corresponding to the suction holes 56 and 60 without performing a time-consuming drilling operation using a complex device, thereby improving the productivity of the chuck table 16.

[0056] The elastic member 70 may be formed of a material other than a thermoplastic elastomer. For example, the elastic member 70 may be formed of a material that hardens while retaining flexibility in response to an external stimulus such as a change in humidity, ultraviolet light irradiation, or light irradiation of a predetermined wavelength.

[0057] Furthermore, the method for forming the elastic member 70 is not limited to the above method. For example, the elastic member 70 may be formed on the chuck table 16 by preparing a sheet-like elastic member 70 in which a large number of suction holes 71 are formed in advance and attaching the elastic member 70 to the holding surface area 59 of the base 51.

[0058] The operation of the cutting device 10 equipped with the chuck table 16 configured as above, and a method of half-cutting the workpiece 11 using the cutting device 10 will be described.

[0059] [Holding process] A holding step is performed in which the plate-shaped workpiece 11 is suction-held on the chuck table 16. First, as shown in Fig. 1, the chuck table 16 is positioned in the attachment / detachment area, and the workpiece 11 is placed on the elastic member 70 of the chuck table 16. The workpiece 11 is placed on the elastic member 70 with one side having the bumps 42 facing downward, and the other side having the device chip 43 and resin layer 44 facing upward (see Fig. 6).

[0060] The control unit 90 opens the on-off valve 64 and operates the suction source 63 to apply suction force to the upper surface of the elastic member 70. This suction force causes the workpiece 11 to be sucked and held on the upper surface of the elastic member 70. With the workpiece 11 being sucked and held, the table feed mechanism 18 moves the chuck table 16 from the attachment / detachment area to the processing area.

[0061] The control unit 90 sets the rotation direction of the chuck table 16 by the table rotation mechanism 19 so that the grid-like planned dividing lines 41 of the workpiece 11 extend in the X-axis direction and the Y-axis direction. In this embodiment, first, the orientation of the chuck table 16 is set so that the longitudinal directions of the rectangular workpiece 11 and the chuck table 16 are oriented in the X-axis direction.

[0062] [Top surface height measurement process] Following the holding step, the chuck table 16 is positioned in the processing area, and the workpiece 11 is held by suction on the upper surface of the elastic member 70 while the top surface height measuring step shown in Fig. 6 is performed. In the top surface height measuring step, the control unit 90 controls the top surface height measuring device 36 to measure the height of the workpiece 11 held on the chuck table 16. As described above, the top surface height measuring device 36 is a height sensor that can measure the height of the workpiece 11 held on the chuck table 16 by non-contact methods such as focusing an imaging unit, projecting and receiving measurement light, and emitting and receiving ultrasonic waves.

[0063] The control unit 90 rotates the ball screw 23 to move the Y-axis moving table 27 and the Z-axis moving table 35, which support the top surface height measuring device 36, in the Y-axis direction to position them above the workpiece 11. Next, the control unit 90 causes the table feed mechanism 18 to move the chuck table 16 in the X-axis direction, which is the cutting feed direction of the workpiece 11 relative to the cutting blade 38, and while the workpiece 11 passes below the top surface height measuring device 36, causes the top surface height measuring device 36 to measure the height of the workpiece 11 over the entire X-axis direction (longitudinal direction of the workpiece 11).

[0064] In the top surface height measurement process, the top surface height of the workpiece 11 is measured at multiple positions in the X-axis direction, which is the cutting feed direction relative to the cutting blade 38. Based on the value of the encoder that detects the amount of movement of the motor of the table feed mechanism 18 and the height information of the workpiece 11 at multiple positions in the X-axis direction measured by the top surface height measuring device 36, top surface height data including height information in the Z-axis direction (height change information) over the entire X-axis direction (longitudinal direction) of the workpiece 11 can be acquired. The acquired top surface height data is stored in the memory unit 92 of the control unit 90.

[0065] For the region between the multiple positions where the top surface height of the workpiece 11 was measured by the top surface height measuring device 36, the control unit 90 can calculate the trend of change in the top surface height of the workpiece 11 based on the relationship between the top surface heights of each measured position, and obtain complementary top surface height data. Therefore, in the top surface height measurement process, the more the number of positions in the X-axis direction where the top surface height of the workpiece 11 is measured and the narrower the interval between the measurement positions, the better the degree of agreement (accuracy) of the top surface height data obtained by measurement with respect to the actual top surface shape of the workpiece 11. The number of positions and intervals where the top surface height of the workpiece 11 is measured are set appropriately, taking into consideration the balance between the processing and time burden required for measurement and calculation and the accuracy of the top surface height data.

[0066] For example, in order to obtain the most accurate top surface height data, the top surface height of the workpiece 11 may be measured continuously (at multiple consecutive height measurement positions) across the entire workpiece 11 in the X-axis direction.

[0067] The intervals between the multiple positions in the X-axis direction where the top surface height of the workpiece 11 is measured may be equal or may vary. For example, if the tendency for warping of the workpiece 11 can be predicted in advance based on information such as the arrangement of the device chip 43 and the resin layer 44, the top surface height measurement step may be performed by increasing the measurement density of the top surface height of the workpiece 11 (narrowing the intervals between the positions where the top surface height is measured) at locations where the warping of the workpiece 11 is expected to be particularly large.

[0068] [Cutting process] Following the upper surface height measurement process, the cutting process shown in Fig. 7 is carried out. In the cutting process, the workpiece 11 is cut by the cutting unit 12 while being held by suction on the upper surface of the elastic member 70. Although Fig. 7 shows only one cutting unit 12, it is possible to use both cutting units 12 in a pair to perform cutting at two locations simultaneously.

[0069] During cutting, the control unit 90 rotates the ball screws 22 and 23 to move the Y-axis moving tables 26 and 27 in the Y-axis direction, thereby positioning the cutting blade 38 of each cutting unit 12 above the planned division line 41 that is the target of cutting. Next, the spindle motor (not shown) provided in each cutting unit 12 rotates the spindle 37 and the cutting blade 38, and rotates the ball screws 29 and 33 to lower the Z-axis moving tables 31 and 35, causing the rotating cutting blade 38 to cut into the top surface of the workpiece 11. Furthermore, the table feed mechanism 18 moves the chuck table 16 (feeds for processing), thereby cutting with the cutting blade 38 along the planned division line 41 that extends in the X-axis direction, which is the longitudinal direction of the workpiece 11, and forming a cut groove 39 in the workpiece 11. In this embodiment, cutting is performed in a half-cut mode, in which the cutting blade 38 cuts into the substrate 40 partway through its thickness, forming a bottomed cut groove 39 that is less deep than the thickness of the workpiece 11.

[0070] In the cutting process, the control unit 90 controls the cutting depth of the cutting blade 38 from the top surface of the workpiece 11 as needed, based on the top surface height data of the workpiece 11 (top surface heights measured at multiple positions in the measurement process) acquired in the previous top surface height measurement process and stored in the memory unit 92, so that the cutting groove 39 has a predetermined depth from the top surface of the workpiece 11. More specifically, while moving the workpiece 11 in the X-axis direction, the control unit 90 controls the position of the cutting unit 12 in the Z-axis direction to raise and lower the cutting blade 38, thereby controlling the cutting depth of the cutting blade 38 from the top surface of the workpiece 11 to be constant throughout the entire cutting groove 39 in the X-axis direction. For example, if the workpiece 11 has a warp like the curve P shown in FIG. 4, top surface height data corresponding to the shape of the warp of the workpiece 11 is stored in the memory unit 92. In other words, in the stored top surface height data, the top surface of the workpiece 11 is highest at both ends in the X-axis direction (longitudinal direction), and gradually decreases as the top surface of the workpiece 11 moves toward the center of the workpiece 11 in the X-axis direction. During cutting, the control unit 90 controls the rotation of the ball screws 29, 33 in accordance with the processing feed operation in the X-axis direction by the table feed mechanism 18, and adjusts the height position of the cutting blade 38 by raising and lowering it as needed so that the cutting depth corresponds to the stored change in height of the top surface of the workpiece 11. By controlling the cutting depth adjustment in this way during cutting, it is possible to perform high-precision cutting on the warped workpiece 11 without any variation in the cutting depth, and form a cut groove 39 of a predetermined depth.

[0071] Furthermore, because the elastic member 70 of the chuck table 16 suction-holds the entire underside of the workpiece 11, it is possible to prevent the workpiece 11 from shifting on the chuck table 16 during cutting. Since the workpiece 11 does not shift on the chuck table 16, cutting can be performed accurately along the planned division line 41, and there is no risk of accidentally cutting device chips 43 that are located away from the planned division line 41. Furthermore, there are no unstable portions of the workpiece 11 that are floating relative to the elastic member 70 of the chuck table 16, and when the cutting blade 38 cuts into the workpiece 11, the entire workpiece 11 is stable and vibrations are suppressed, so there is no risk of the cutting blade 38 being subjected to an excessive load and being damaged.

[0072] When cutting along the planned division line 41 is completed, the control unit 90 rotates the ball screws 29, 33 to raise each cutting unit 12 and separate it from the workpiece 11, and rotates the ball screws 22, 23 to move each cutting unit 12 in the Y-axis direction, thereby positioning the cutting blade 38 of each cutting unit 12 above the planned division line 41 that is the target of the next cutting. Then, in the same manner as described above, cutting is performed along the planned division line 41 using the cutting blade 38, forming a cut groove 39.

[0073] When cutting along all of the planned division lines 41 extending in the longitudinal direction of the workpiece 11 is completed, the process moves to a step of cutting the planned division lines 41 extending in the lateral direction of the workpiece 11. The control unit 90 operates the table rotation mechanism 19 to rotate the chuck table 16 by 90°. This rotation brings the plurality of uncut planned division lines 41 extending in the lateral direction of the workpiece 11 into a state of extending in the X-axis direction.

[0074] The cutting process along the dividing lines 41 extending in the short direction of the workpiece 11 is performed in the same manner as the cutting process along the dividing lines 41 extending in the long direction of the workpiece 11 described above, and will therefore only be briefly described.

[0075] At the stage where the chuck table 16 is rotated 90°, the workpiece 11 is already held by suction to the chuck table 16 (the state where the holding process has been performed), and the top surface height measuring process is performed after the chuck table 16 is rotated. In the top surface height measuring process, the chuck table 16 is moved in the X-axis direction by the table feed mechanism 18, and the top surface height of the workpiece 11 is measured at multiple positions in the X-axis direction over the entire X-axis direction (short side direction) of the workpiece 11 using the top surface height measuring device 36. The top surface height data of the workpiece 11 obtained by the measurement is stored in the memory unit 92 of the control unit 90.

[0076] Next, a cutting process is performed. In the cutting process, the cutting blade 38 of the cutting unit 12 is positioned above a planned dividing line 41 extending in the X-axis direction (short direction) of the workpiece 11, the rotating cutting blade 38 is lowered to cut into the upper surface of the workpiece 11, and the chuck table 16 is moved in the X-axis direction by the table feed mechanism 18 to form a cutting groove 39 along the planned dividing line 41.

[0077] During cutting processing, the control unit 90 performs lifting control to adjust the cutting depth of the cutting blade 38 (the position of the cutting unit 12 in the Z-axis direction) so that the cutting groove 39 is of a predetermined depth from the top surface of the workpiece 11 based on the top surface height data of the workpiece 11 stored in the memory unit 92, thereby maintaining the cutting depth of the cutting groove 39 constant.

[0078] When cutting along the planned dividing lines 41 is completed, the control unit 90 positions the cutting blades 38 of each cutting unit 12 above the next planned dividing line 41 to be cut, and performs cutting along that planned dividing line 41. When cutting along all planned dividing lines 41 extending in the short direction of the workpiece 11 is completed, the cutting process is completed.

[0079] Just as when cutting grooves 39 are formed by cutting in the longitudinal direction of the workpiece 11, when cutting grooves 39 in the lateral direction of the workpiece 11, the elastic member 70 of the chuck table 16 holds the entire underside of the workpiece 11 by suction, so that the workpiece 11 does not shift on the chuck table 16, preventing damage to the cutting blade 38 and enabling accurate cutting along the intended division line 41.

[0080] In this embodiment, the top surface height measurement process and cutting process are performed with the longitudinal direction of the workpiece 11 facing the X-axis direction, and then the top surface height measurement process and cutting process are performed with the short side direction of the workpiece 11 facing the X-axis direction.However, it is also possible to first measure the top surface height in both the longitudinal and short side directions of the workpiece 11 (i.e., the entire surface of the workpiece 11) together, and then perform cutting processing along all of the planned division lines 41 in the cutting process without inserting the top surface height measurement process in between.

[0081] 8 shows a modified chuck table 80. Regarding the modified chuck table 80, parts common to the chuck table 16 of the above embodiment are denoted by the same reference numerals and description thereof will be omitted.

[0082] A porous plate 81 made of porous ceramics or the like having numerous pores is provided in the inner region 55 of the lower pedestal 50 of the chuck table 80. The porous plate 81 is connected to a suction source 63 via a suction path 62, and an on-off valve 64 is provided in the suction path 62.

[0083] The holding surface area 59 of the base 51 of the chuck table 80 has an elastic member 82 made of elastomer arranged to a predetermined thickness. The elastic member 82 is made of a foamed elastomer having many pores, and like the elastic member 70 of the above embodiment, is a low-resilience flexible member that has excellent shape-following ability to the workpiece 11. The elastic member 82 is formed by adhering a sheet-like foamed elastomer to the holding surface area 59 of the base 51.

[0084] Although not shown in Fig. 8, a large number of suction holes 60 (see Fig. 3) are formed penetrating the base 51 in the vertical direction (Z-axis direction). The upper end of each suction hole 60 is located at a position where it connects to the lower surface of the elastic member 82, and the lower end of each suction hole 60 is located at a position where it connects to the upper surface of the porous plate 81.

[0085] When the on-off valve 64 is opened and the suction source 63 is operated, air is sucked through the numerous pores in the porous plate 81, the numerous suction holes 60, and the numerous pores in the elastic member 82, and a suction force is applied to the holding surface of the chuck table 80 formed by the elastic member 82, so that the entire underside of the workpiece 11 can be held by suction.

[0086] Like the elastic member 70 of the above embodiment, the elastic member 82 preferably has a dynamic viscoelasticity of 0.1 tan δ or more and 0.4 tan δ or less at a temperature of 20° C. to 30° C., and a thickness of 0.1 mm to 1 mm.

[0087] The chuck table 80 having the above-described configuration is provided with an elastomer elastic member 82 arranged at a predetermined thickness over the entire holding surface area 59 of the base 51, and thus, similar to the chuck table 16 of the above-described embodiment, the elastic member 82 can be brought into close contact with the entire underside of a warped workpiece 11 or the entire underside of a workpiece 11 having unevenness such as bumps 42 on the underside, and held by suction.

[0088] As in the case of using the chuck table 16 of the above embodiment, by implementing a half-cut method including a holding step of holding the workpiece 11 on the chuck table 80, a top surface height measurement step of measuring the top surface height of the workpiece 11 at multiple positions in the cutting feed direction, and a cutting step of cutting the workpiece 11 while raising and lowering the cutting blade 38 based on the multiple measured top surface heights, high-precision cutting can be performed to form a cutting groove of a predetermined depth in the workpiece 11 even when a warped workpiece 11 is held on the chuck table 80.

[0089] As can be seen from the above embodiments and variations, the elastic member (70, 82) placed on the entire holding surface of the chuck table (16, 80) need only conform to the shape of the warped workpiece and adhere to the entire underside of the workpiece, and there are no restrictions on the material or composition.

[0090] As described above, the chuck tables 16, 80 are provided with the elastomer elastic members 70, 82 arranged to a predetermined thickness on the entire holding surface of the base 51, and thereby the entire underside of the warped workpiece 11 can be sucked and held by the elastic members 70, 82. Rather than correcting the warp of the workpiece 11 to make it flat, the elastic members 70, 82 that make up the chuck tables 16, 80 conform to the shape of the underside of the workpiece 11 and come into close contact with it, so that a complex mechanism or strong suction force for correcting the warp of the workpiece 11 is not required, and the workpiece 11 can be stably held even in its warped state.

[0091] The chuck tables 16, 80 are provided with a lower pedestal 50 and base 51 that are excellent in strength, and are provided with elastic members 70, 82 only on the top part that overlaps with the base 51, so that compared to a chuck table made entirely of elastic members, they have high rigidity and can obtain the effect of closely adhering to the entire underside of the workpiece 11 and holding it by suction. In other words, it is possible to achieve both high levels of stability in supporting the workpiece 11 and high levels of conformability to the shape of the underside of the workpiece 11.

[0092] Furthermore, by performing the half-cut method including the holding step, the upper surface height measuring step, and the cutting step, the workpiece 11 held in a warped state is cut with a cutting depth that corrects for the influence of the warp, so that a cutting groove of a predetermined depth can be formed with excellent processing accuracy.

[0093] The chuck table of the present invention is particularly useful for rectangular package substrates such as the workpiece 11 in the above embodiment, because these substrates are particularly susceptible to warping and lifting off the chuck table. However, the plate-shaped workpieces held by the holding surface of the chuck table are not limited to rectangular package substrates. For example, the present invention can also be applied to a chuck table that holds a disk-shaped wafer.

[0094] Furthermore, although the chuck table of the present invention is highly useful in cutting machines such as those in the above-described embodiment, it can also be applied to processing machines other than cutting machines. In addition to cutting machines, laser processing machines, grinding machines, polishing machines, and the like are known as processing machines that suction-hold a plate-shaped workpiece with a chuck table. A chuck table to which the present invention is applied may be used when holding a warped workpiece in these various machines.

[0095] The embodiments of the present invention are not limited to the above-described embodiments and modifications, and may be variously changed, substituted, or modified without departing from the spirit of the technical idea of the present invention. Furthermore, if the technical idea of the present invention can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea of the present invention. [Industrial Applicability]

[0096] As described above, the chuck table of the present invention can suction-hold the entire underside of a warped workpiece, improving the quality of machining performed while the workpiece is held on the chuck table and preventing damage to machining tools such as cutting blades. Furthermore, the half-cut method of the present invention can form a cutting groove in a warped workpiece with high precision, with a depth less than the thickness of the workpiece, thereby improving the quality of cutting. [Explanation of symbols]

[0097] 10: Cutting equipment 11: Workpiece (plate-shaped workpiece) 12: Cutting unit 16: Chuck table 18: Table feed mechanism 19: Table rotation mechanism 26: Y-axis moving table 27: Y-axis moving table 31: Z-axis moving table 35: Z-axis moving table 36: Top surface height measuring instrument 38: Cutting blade 39: Cutting groove 40: Substrate 41: Planned division line 42: Bump 43: Device chip 44: Resin layer 50: Lower pedestal 51: Foundation 52: Rotating plate 53: Screw hole 54:Outer area 55: Inner area 56: Suction hole 57:Through hole 58:Outer area 59: Holding surface area (holding surface) 60: Suction hole 61: Fixing screw 62:Suction path 63: Suction source 64: On-off valve 70: Elastic member 71: Suction hole 80: Chuck table 81: Porous plate 82: Elastic member 90: Control unit 91: Processing section 92: Storage section

Claims

1. A chuck table that suction-holds a plate-shaped workpiece on a holding surface, The chuck table comprises a base having the holding surface on its upper surface, a plurality of suction holes arranged on the holding surface that penetrate the lower surface and can communicate with a suction source, and an elastomer elastic member arranged to a predetermined thickness over the entire holding surface.

2. 2. The chuck table according to claim 1, wherein the elastic member has a dynamic viscoelasticity of 0.1 tan δ or more and 0.4 tan δ or less at a temperature of 20°C to 30°C.

3. 3. The chuck table according to claim 1, wherein the elastic member is a thermoplastic elastomer.

4. 3. The chuck table according to claim 1, wherein the elastic member is a foamed elastomer.

5. 3. The chuck table according to claim 1, wherein the plate-shaped workpiece has bumps on one surface thereof, and the bumps are held in contact with the elastic member.

6. 2. A half-cutting method for forming a cutting groove having a depth less than the thickness of a plate-shaped workpiece held on the chuck table according to claim 1 with a cutting blade, comprising: a holding step of suction-holding the plate-shaped workpiece on the chuck table; a workpiece upper surface height measuring step of moving the plate-shaped workpiece held in the holding step in a cutting feed direction and measuring the upper surface height of the plate-shaped workpiece at a plurality of positions in the cutting feed direction relative to the cutting blade; a cutting step of moving the plate-shaped workpiece in a cutting feed direction while raising and lowering the cutting blade to form the cut groove of a predetermined depth from the top surface based on the plurality of top surface heights measured in the top surface height measuring step; A half-cut method comprising:

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