Processing method of workpiece

Abstract

To provide a workpiece processing method capable of improving the processing quality of a workpiece which includes a plurality of laminated layers.SOLUTION: The workpiece processing method is for cutting, by a cutting tool, a workpiece including a metal layer and a ceramic layer which have been laminated. The cutting tool is provided with a plurality of cutting parts on an outer peripheral part. Each of the cutting parts is provided with a tip, a first base end, a second base end, a first surface connected to the tip and the first base end, and a second surface connected to the tip and the second base end. A distance between the tip and the first base end is shorter than that between the tip and the second base end. This method comprises: a holding step of holding the workpiece on a chuck table; and a cutting step of rotating the cutting tool so as to position the second surface before the first surface in a rotation direction, putting the tool into the workpiece held on the chuck table, and then cutting the workpiece.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for machining a workpiece by cutting the workpiece with a cutting tool. [Background technology]

[0002] A semiconductor wafer on which multiple devices are formed is divided and singulated to produce device chips each including the devices. Furthermore, a package substrate is obtained by mounting multiple device chips on a base substrate and covering the mounted device chips with a resin sealing material (mold resin). Package devices each including multiple packaged device chips are produced by dividing and singulating this package substrate. The device chips and package devices are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] Cutting machines are used to divide workpieces such as semiconductor wafers and package substrates. Cutting machines are equipped with a chuck table that holds the workpiece and a cutting unit that performs cutting on the workpiece. The cutting unit has a built-in spindle, and an annular cutting tool (cutting blade) is attached to the tip of the spindle. The workpiece is held by the chuck table, and the cutting tool is rotated and cut into the workpiece, cutting and dividing it.

[0004] Cutting devices are highly versatile and can cut workpieces of various materials, structures, and shapes. For example, cutting devices can also be used for green cutting of ceramic plate-like objects. In this case, a cutting blade with multiple saw-tooth cutting edges on its outer periphery may be used as the cutting tool (see Patent Document 1). The cutting edges have a rake face and a flank face, and the cutting tool rotates so that the rake face is positioned forward of the flank face in the direction of rotation. By bringing the cutting edges into contact with the workpiece while rotating the cutting tool, the workpiece is cut and divided into multiple chips. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-179505 Summary of the Invention [Problem to be solved by the invention]

[0006] Cutting tools (cutting blades) equipped with the saw-tooth cutting edge described above are also used to process workpieces (laminates) that include multiple stacked layers. For example, a workpiece formed by alternately stacking metal and ceramic layers can be cut and divided using the cutting tool to obtain chips that include metal and ceramic layers. These chips are then subjected to firing, external electrode formation, plating, and other processes to produce multilayer ceramic capacitors (MLCCs) with metal layers as internal electrodes and ceramic layers as dielectrics.

[0007] However, when a cutting tool with a cutting edge cuts a workpiece, the steep rake face rotates at high speed while coming into contact with the workpiece. This places a heavy load on the workpiece, which can disrupt the regular lamination of the metal and ceramic layers on the cut surface (cut surface) of the chip. This leads to a deterioration in the processing quality of the workpiece and a decrease in the yield of chips obtained by dividing the workpiece.

[0008] The present invention has been made in consideration of such problems, and aims to provide a method for processing a workpiece that can improve the processing quality of a workpiece that includes multiple stacked layers. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a method for machining a workpiece, the workpiece including laminated metal layers and ceramic layers, using a cutting tool, the cutting tool having a plurality of cutting edges on its outer periphery, the cutting edges having a tip, a first base end, a second base end, a first surface connected to the tip and the first base end, and a second surface connected to the tip and the second base end, the distance between the tip and the first base end being shorter than the distance between the tip and the second base end, the method including: a holding step for holding the workpiece using a chuck table; and a cutting step for rotating the cutting tool so that the second surface is positioned forward of the first surface in the rotational direction, and cutting the workpiece held by the chuck table by cutting the workpiece.

[0010] Preferably, the second surface is a curved surface that curves in the opposite direction to the first surface. [Effects of the Invention]

[0011] In one embodiment of the present invention, a cutting tool having multiple cutting edges is rotated in a reverse direction and driven into the workpiece to cut the workpiece. This allows the second surface, which is an inclined surface equivalent to the flank when the cutting tool is rotated in the normal forward direction, to function as a rake face when cutting a workpiece having a laminated structure. As a result, the processing load on the workpiece is reduced, making it less likely for the laminated structure of the workpiece to collapse, and improving processing quality. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. 3(A) is a front view showing the cutting tool, and FIG. 3(B) is a front view showing the cutting part of the cutting tool. [Figure 4] FIG. 2 is an exploded perspective view showing the cutting unit. [Figure 5]FIG. 5(A) is a front view showing a cutting tool that rotates in the forward direction, and FIG. 5(B) is a front view showing a cutting tool that rotates in the reverse direction. [Figure 6] FIG. 2 is a partial cross-sectional front view showing the cutting device in which a workpiece is held by a chuck table. [Figure 7] FIG. 7(A) is a partial cross-sectional front view showing a cutting device that cuts a workpiece by down-cutting, and FIG. 7(B) is a front view showing a cutting part of a cutting tool that cuts a workpiece by down-cutting. [Figure 8] FIG. 8(A) is a partial cross-sectional front view showing a cutting device that cuts a workpiece by up-cutting, and FIG. 8(B) is a front view showing a cutting part of a cutting tool that cuts a workpiece by up-cutting. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment according to one aspect of the present invention will be described below with reference to the accompanying drawings. First, a configuration example of a cutting device that can be used in the method for processing a workpiece according to this embodiment will be described. FIG. 1 is a perspective view showing a cutting device 2 that performs cutting processing on a workpiece 11. In FIG. 1, the X-axis direction (processing feed direction, first horizontal direction, left-right direction) and the Y-axis direction (indexing feed direction, second horizontal direction, front-rear direction) are perpendicular to each other. Furthermore, the Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0014] The cutting device 2 includes a rectangular parallelepiped base 4 that supports or houses each of the components that make up the cutting device 2. A rectangular opening 4a is provided at a corner on the front end side of the base 4. A cassette support table 6 that is raised and lowered by a lifting mechanism (not shown) is provided inside the opening 4a. A cassette 8 that can house multiple workpieces 11 that are to be machined by the cutting device 2 is placed on the cassette support table 6. In FIG. 1, the outline of the cassette 8 is indicated by a two-dot chain line.

[0015] FIG. 2 is a perspective view showing a workpiece 11. The workpiece 11 is a plate- or sheet-like member (laminate) including a plurality of stacked layers, and includes a front surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other. For example, the workpiece 11 is a rectangular laminate sheet used in the manufacture of multilayer ceramic chip capacitors (MLCCs), and includes a plurality of metal layers 13 and a plurality of ceramic layers 15. For ease of explanation, the thicknesses of the metal layers 13 and the ceramic layers 15 are exaggerated in FIG. 2.

[0016] The metal layer 13 is a rectangular layer made of a metal such as nickel, copper, or silver. The ceramic layer 15 is a rectangular layer made of a pre-sintered ceramic such as titanium oxide, barium titanate, or calcium zirconate. The metal layer 13 and the ceramic layer 15 are alternately stacked in the thickness direction of the workpiece 11 (thickness direction of the metal layer 13 and the ceramic layer 15). That is, each ceramic layer 15 is sandwiched between a pair of metal layers 13.

[0017] For example, the workpiece 11 is formed by stacking and pressing a plurality of sheet-shaped dielectrics (green sheets) made of pre-sintered ceramic and coated with electrode paste. There is no limit to the thickness and number of the metal layers 13 and ceramic layers 15 to be stacked.

[0018] The workpiece 11 is cut and divided using a cutting device 2 (see FIG. 1 ), thereby obtaining chips of a desired size, each including an individual metal layer 13 and a ceramic layer 15. These chips are then subjected to firing, external electrode formation, plating, and other processes to produce a multilayer ceramic capacitor in which the metal layer 13 serves as an internal electrode and the ceramic layer 15 serves as a dielectric. However, the structure, material, and the like of the workpiece 11 can be changed as appropriate depending on the application of the workpiece 11.

[0019] When the workpiece 11 is machined by the cutting device 2, the workpiece 11 is supported by an annular frame 17. The frame 17 is made of a metal such as SUS (stainless steel), and a circular opening 17a is provided in the center of the frame 17, penetrating the frame 17 in the thickness direction. The diameter of the opening 17a is larger than the length of each side of the workpiece 11.

[0020] Tape (dicing tape) 19 is attached to the workpiece 11 and the frame 17. For example, the tape 19 includes a circular film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive. The adhesive layer may be an ultraviolet-curable resin that hardens when exposed to ultraviolet light.

[0021] With the workpiece 11 placed inside the opening 17a of the frame 17, the center of the tape 19 is attached to the back surface 11b of the workpiece 11, and the outer periphery of the tape 19 is attached to the frame 17. This causes the workpiece 11 to be supported by the frame 17 via the tape 19. Then, the workpiece 11, supported by the frame 17, is housed in the cassette 8 shown in FIG.

[0022] A rectangular opening 4b is provided behind the opening 4a, with its longitudinal direction aligned with the X-axis direction. A chuck table (holding table) 10 for holding a workpiece 11 is provided inside the opening 4b. The upper surface of the chuck table 10 is a flat surface that is roughly parallel to the horizontal plane (XY plane), and forms a holding surface 10a for holding the workpiece 11. The holding surface 10a is connected to a suction source (not shown), such as an ejector, via a flow path (not shown), a valve (not shown), and the like, provided inside the chuck table 10.

[0023] A moving mechanism 12 that moves the chuck table 10 along the X-axis direction is connected to the chuck table 10. For example, the moving mechanism 12 is a ball screw type moving mechanism that includes an X-axis ball screw (not shown) arranged along the X-axis direction and an X-axis pulse motor (not shown) that rotates the X-axis ball screw.

[0024] The moving mechanism 12 also includes a flat table cover 14 that is provided to surround the chuck table 10. Furthermore, accordion-shaped dust-proof and drip-proof covers 16 that are extendable and contractible along the X-axis direction are provided on both sides of the table cover 14. The table cover 14 and the dust-proof and drip-proof covers 16 are installed so as to cover the components of the moving mechanism 12 (such as the X-axis ball screw and X-axis pulse motor) that are housed inside the opening 4b.

[0025] A rotation drive source (not shown), such as a motor, is connected to the chuck table 10 to rotate the chuck table 10 around a rotation axis that is generally parallel to the Z-axis direction. In addition, a plurality of clamps 18 are provided around the periphery of the chuck table 10 to grip and fix a frame 17 that supports the workpiece 11.

[0026] A transfer mechanism (not shown) is provided near the openings 4a and 4b to transfer the workpiece 11 between the cassette 8 and the chuck table 10. The workpiece 11 is drawn out of the cassette 8 by the transfer mechanism and transferred to the chuck table 10.

[0027] Cutting units 20a and 20b that cut the workpiece 11 are provided above the chuck table 10. In addition, a gate-shaped support structure 22 that supports the cutting units 20a and 20b is disposed on the upper surface of the base 4 so as to straddle the opening 4b.

[0028] Movement mechanisms 24a and 24b are provided on both end portions on the front surface side of the support structure 22. The movement mechanism 24a is a ball screw type movement mechanism that moves the cutting unit 20a along the Y-axis direction and the Z-axis direction, and the movement mechanism 24b is a ball screw type movement mechanism that moves the cutting unit 20b along the Y-axis direction and the Z-axis direction. The movement mechanisms 24a and 24b are attached to a pair of Y-axis guide rails 26 that are arranged on the front surface side of the support structure 22 along the Y-axis direction.

[0029] The movement mechanism 24a includes a flat Y-axis moving plate 28a. The Y-axis moving plate 28a is slidably mounted on a pair of Y-axis guide rails 26. A nut portion (not shown) is provided on the rear surface side of the Y-axis moving plate 28a. A Y-axis ball screw 30a, which is disposed generally parallel to the Y-axis guide rails 26, is threadedly engaged with this nut portion. A Y-axis pulse motor 32 that rotates the Y-axis ball screw 30a is connected to an end of the Y-axis ball screw 30a. When the Y-axis pulse motor 32 rotates the Y-axis ball screw 30a, the Y-axis moving plate 28a moves in the Y-axis direction along the Y-axis guide rails 26.

[0030] A pair of Z-axis guide rails 34a are fixed along the Z-axis direction to the front surface of the Y-axis moving plate 28a. A flat Z-axis moving plate 36a is slidably mounted on the pair of Z-axis guide rails 34a. A nut portion (not shown) is provided on the rear surface of the Z-axis moving plate 36a. A Z-axis ball screw 38a, which is disposed generally parallel to the Z-axis guide rails 34a, is threadedly engaged with this nut portion. Furthermore, a Z-axis pulse motor 40a that rotates the Z-axis ball screw 38a is connected to the end of the Z-axis ball screw 38a.

[0031] When the Z-axis ball screw 38a is rotated by the Z-axis pulse motor 40a, the Z-axis moving plate 36a moves in the Z-axis direction along the Z-axis guide rail 34a. The cutting unit 20a is fixed to the lower part of the Z-axis moving plate 36a.

[0032] Similarly, the movement mechanism 24b includes a flat Y-axis moving plate 28b. The Y-axis moving plate 28b is slidably mounted on a pair of Y-axis guide rails 26. A nut portion (not shown) is provided on the rear surface side of the Y-axis moving plate 28b. A Y-axis ball screw 30b, which is disposed substantially parallel to the Y-axis guide rails 26, is threadedly engaged with this nut portion. A Y-axis pulse motor (not shown) that rotates the Y-axis ball screw 30b is coupled to an end of the Y-axis ball screw 30b. When the Y-axis pulse motor rotates the Y-axis ball screw 30b, the Y-axis moving plate 28b moves in the Y-axis direction along the Y-axis guide rails 26.

[0033] A pair of Z-axis guide rails 34b are fixed along the Z-axis direction to the front surface of the Y-axis moving plate 28b. A flat Z-axis moving plate 36b is slidably mounted on the pair of Z-axis guide rails 34b. A nut portion (not shown) is provided on the rear surface of the Z-axis moving plate 36b. A Z-axis ball screw 38b, which is disposed substantially parallel to the Z-axis guide rails 34b, is threadedly engaged with this nut portion. Furthermore, a Z-axis pulse motor 40b that rotates the Z-axis ball screw 38b is connected to the end of the Z-axis ball screw 38b.

[0034] When the Z-axis ball screw 38b is rotated by the Z-axis pulse motor 40b, the Z-axis moving plate 36b moves in the Z-axis direction along the Z-axis guide rail 34b. The cutting unit 20b is fixed to the lower part of the Z-axis moving plate 36b.

[0035] An imaging unit 42 is provided adjacent to the cutting unit 20a to capture an image of a subject such as the workpiece 11 held by the chuck table 10. The imaging unit 42 includes an imaging element such as a CCD (Charged-Coupled Device) sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, and an optical system including optical elements such as an objective lens. The type of imaging unit 42 can be appropriately selected depending on the material of the workpiece 11, etc. For example, a visible light camera or an infrared camera is used as the imaging unit 42. The image captured by the imaging unit 42 is used for aligning the workpiece 11 with the cutting units 20a and 20b, etc.

[0036] A circular opening 4c is provided behind the opening 4b. A cleaning unit 44 for cleaning the workpiece 11 is provided inside the opening 4c. The cleaning unit 44 includes a spinner table 46 that holds and rotates the workpiece 11, and a nozzle 48 that supplies cleaning fluid to the workpiece 11 held by the spinner table 46.

[0037] The upper surface of the spinner table 46 is a flat surface that is roughly parallel to the horizontal plane (XY plane) and constitutes a holding surface 46a that holds the workpiece 11. The holding surface 46a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like that are provided inside the spinner table 46. In addition, the spinner table 46 is connected to a rotation drive source (not shown) such as a motor that rotates the spinner table 46 around a rotation axis that is roughly parallel to the Z-axis direction.

[0038] Nozzle 48 for supplying a cleaning fluid is disposed above spinner table 46. For example, a liquid (such as pure water) or a mixed fluid containing a liquid (such as pure water) and a gas (such as air) is used as the cleaning fluid. With workpiece 11 held by spinner table 46, the spinner table 46 is rotated while supplying the cleaning fluid from nozzle 48 toward workpiece 11, thereby cleaning workpiece 11.

[0039] A transfer mechanism (not shown) is provided near the openings 4b and 4c to transfer the workpiece 11 between the chuck table 10 and the spinner table 46. After the workpiece 11 is machined by the cutting units 20a and 20b, it is transferred from the chuck table 10 to the spinner table 46 by the transfer mechanism and cleaned. Then, the cleaned workpiece 11 is carried into the cassette 8 by the transfer mechanism.

[0040] A cover 50 is provided on the upper side of the base 4 to cover the components mounted on the base 4. In Fig. 1, the outline of the cover 50 is indicated by a two-dot chain line.

[0041] A display unit (display section, display device) 52 that displays information related to the cutting device 2 is provided on the front side of the cover 50. The display unit 52 can be configured with various displays, and displays information related to the processing of the workpiece 11 (processing conditions, processing status, etc.). For example, a touch panel display is used as the display unit 52. In this case, the display unit 52 also functions as an input unit (input section, input device) for inputting information to the cutting device 2, and the operator can input information to the cutting device 2 by touching the display unit 52. In other words, the display unit 52 functions as a user interface.

[0042] An alarm unit (alarm section, alarm device) 54 that notifies the operator of information is provided on the top of the cover 50. For example, the alarm unit 54 is an indicator light (warning light), which lights up or flashes when an abnormality occurs in the cutting device 2 to notify the operator of the error. However, there is no limitation on the type of alarm unit 54. For example, the alarm unit 54 may be a speaker that notifies the operator of information by sound or voice.

[0043] The cutting device 2 also includes a control unit (controller, controller) 56 that controls the cutting device 2. The control unit 56 is connected to each of the components that make up the cutting device 2 (the cassette support base 6, the chuck table 10, the moving mechanism 12, the clamp 18, the cutting units 20a and 20b, the moving mechanisms 24a and 24b, the imaging unit 42, the cleaning unit 44, the display unit 52, the notification unit 54, etc.).

[0044] The control unit 56 outputs control signals to each component of the cutting device 2, thereby controlling the operation of each component and operating the cutting device 2. For example, the control unit 56 is configured by a computer, and includes a processor such as a CPU (Central Processing Unit) that performs calculations necessary for the operation of the cutting device 2, and memories such as a ROM (Read Only Memory) and RAM (Random Access Memory) that store various information (data, programs, etc.) used for operating the cutting device 2.

[0045] An annular cutting tool (cutting blade) 58 for cutting the workpiece 11 is attached to each of the cutting units 20a and 20b. This positions the pair of cutting tools 58 facing each other. Each of the cutting units 20a and 20b cuts the workpiece 11 by rotating the cutting tool 58 and causing it to cut into the workpiece 11 held by the chuck table 10. However, the number of cutting units provided in the cutting device 2 may be one.

[0046] 3(A) is a front view showing cutting tool 58. For example, cutting tool 58 is an annular cutting blade (metal saw, cemented carbide cutter) made of metal such as cemented carbide or stainless steel and containing no abrasive grains.

[0047] When cutting tool 58 is a metal saw made of cemented carbide, the metal contained in the cemented carbide can be selected appropriately. For example, cutting tool 58 is made of a composite material (alloy) obtained by blending and sintering a carbide of a metal such as tungsten, chromium, molybdenum, titanium, zirconium, hafnium, vanadium, niobium, or tantalum with an iron-based metal (iron, cobalt, nickel, or the like). In particular, a WC-Co alloy containing tungsten carbide (WC) and cobalt exhibits high hardness over a wide temperature range and has excellent mechanical strength, making it a suitable material for cutting tool 58.

[0048] However, there is no limitation on the material of cutting tool 58. For example, cutting tool 58 may be an annular grinding wheel formed by fixing abrasive grains made of diamond, cubic boron nitride (cBN), or the like with a binder made of metal, ceramics, resin, or the like.

[0049] A circular opening 58a is provided in the center of the cutting tool 58, penetrating the cutting tool 58 in the thickness direction. In addition, a plurality of saw-tooth-shaped blade portions (protrusions, convex portions, saw blades) 60 are provided on the outer periphery of the cutting tool 58, protruding radially outward from the cutting tool 58. The plurality of blade portions 60 are formed in roughly the same shape and are arranged at roughly equal intervals along the circumferential direction of the cutting tool 58.

[0050] FIG. 3(B) is a front view showing the blade portion 60 of the cutting tool 58. The blade portion 60 has a distal end 60a, a first base end 60b, and a second base end 60c. The distal end 60a corresponds to the apex of the blade portion 60 and is located farthest from the center of the cutting tool 58 in a front view. The first base end 60b and the second base end 60c correspond to the bottom of the blade portion 60 and are located closest to the center of the cutting tool 58 between two adjacent blade portions 60 in a front view. The first base end 60b of each blade portion 60 is connected to the second base end 60c of one adjacent blade portion 60. The second base end 60c of each blade portion 60 is connected to the first base end 60b of the other adjacent blade portion 60. For example, the distal end 60a, the first base end 60b, and the second base end 60c are each formed linearly along the thickness direction of the cutting tool 58.

[0051] The blade portion 60 also includes a first surface 60d connected to the distal end 60a and the first base end 60b, and a second surface 60e connected to the distal end 60a and the second base end 60c. The distance a between the distal end 60a and the first base end 60b is shorter than the distance b between the distal end 60a and the second base end 60c. Therefore, the inclination angle of the first surface 60d relative to the radial direction of the cutting tool 58 is smaller than the inclination angle of the second surface 60e relative to the radial direction of the cutting tool 58. That is, the blade portion 60 is formed so that the first surface 60d is steeper than the second surface 60e. For example, the first surface 60d is formed parallel to the radial direction of the cutting tool 58 (inclination angle = 0°), and the second surface 60e is formed so as to be inclined relative to the radial direction of the cutting tool 58 (inclination angle > 0°).

[0052] The first surface 60d and the second surface 60e may each be a flat surface or a curved surface. When the first surface 60d is a curved surface, the center of curvature of the first surface 60d is positioned on the opposite side of the second surface 60e from the first surface 60d, and the first surface 60d is formed so as to curve toward the second surface 60e. When the second surface 60e is a curved surface, the center of curvature of the second surface 60e is positioned on the first surface 60d side from the second surface 60e, and the second surface 60e is formed so as to curve toward the opposite side of the first surface 60d.

[0053] The cutting tool 58 is attached to the cutting units 20a and 20b (see FIG. 1). The cutting units 20a and 20b will be described in detail below. Note that although an example of the configuration of the cutting unit 20a will be described here, the cutting unit 20b can also be configured in the same way as the cutting unit 20a.

[0054] 4 is an exploded perspective view showing the cutting unit 20a. The cutting unit 20a includes a columnar housing 62 connected to the moving mechanism 24a (see FIG. 1). The housing 62 accommodates a cylindrical spindle 64 arranged along the Y-axis direction. The tip (one end) of the spindle 64 is exposed from the housing 62, and a rotation drive source (not shown), such as a motor, is connected to the base end (the other end) of the spindle 64. An opening 64a is provided at the tip of the spindle 64, and a thread groove 64b is formed on the inner wall of the opening 64a.

[0055] A blade mount 66 is fixed to the tip of the spindle 64. The blade mount 66 includes a disk-shaped flange 68 and a cylindrical boss (support shaft) 70 that protrudes from a surface 68a of the flange 68. The blade mount 66 also has an opening 66a that passes through the centers of the flange 68 and the boss 70. The blade mount 66 is fixed to the tip of the spindle 64 by inserting a fixing bolt 72 into the opening 64a of the spindle 64 through the opening 66a of the blade mount 66 and tightening it into the thread groove 64b.

[0056] An annular protrusion 68b protruding from the surface 68a of the outer periphery of the flange 68 is provided along the outer periphery of the flange 68 on the side of the surface 68a. The tip surface of the protrusion 68b is a flat surface that is generally parallel to the surface 68a and forms a support surface that supports the cutting tool 58. In addition, a thread groove 70a is formed on the outer periphery of the boss 70.

[0057] The cutting tool 58 and an annular flange (pressing flange) 74 made of metal or the like are attached to the blade mount 66. A circular opening 74a is provided in the center of the flange 74, penetrating the flange 74 in the thickness direction.

[0058] When the boss portion 70 of the blade mount 66 is inserted into the opening 58a of the cutting tool 58 and the opening 74a of the flange 74, in that order, the cutting tool 58 and the flange 74 are supported by the blade mount 66. In this state, when the annular fixing nut 76 is screwed into the thread groove 70a of the boss portion 70 and tightened, the cutting tool 58 and the flange 74 are fixed to the blade mount 66. As a result, the cutting tool 58 is sandwiched between the flange portion 68 and the flange 74 and attached to the tip of the spindle 64.

[0059] Also attached to the housing 62 is a blade cover 78 that covers the cutting tool 58 attached to the tip (blade mount 66) of the spindle 64. The blade cover 78 includes a main body 80 fixed to the tip of the housing 62, and a slide cover 82 that is slidable along the X-axis direction to move toward and away from the main body 80.

[0060] The slide cover 82 is connected to the main body 80 via an air cylinder 84. When air is supplied to a connector 86 provided on the main body 80, the air cylinder 84 is driven, and the slide cover 82 slides along the X-axis direction away from the main body 80. This opens the blade cover 78, allowing the cutting tool 58 to be attached to the tip of the spindle 64. After the cutting tool 58 is attached, the slide cover 82 is slid toward the main body 80 to close the blade cover 78, thereby covering the cutting tool 58.

[0061] The main body 80 is provided with a connector 88 to which a liquid (cutting fluid) such as pure water is supplied, and a cutting fluid supply path (not shown) connected to the connector 88. The tip of the cutting fluid supply path opens toward the outer periphery of the cutting tool 58. When cutting fluid is supplied to the connector 88, the cutting fluid flows into the cutting fluid supply path and is supplied to the outer periphery of the cutting tool 58.

[0062] The slide cover 82 is provided with a pair of connectors 90 through which a liquid (cutting fluid) such as pure water is supplied, and a pair of nozzles 92 connected to the pair of connectors 90. The pair of nozzles 92 are arranged to sandwich the lower part of the cutting tool 58 attached to the tip of the spindle 64. The tip of the nozzle 92 is provided with a cutting fluid supply port (not shown) that opens toward the cutting tool 58. When cutting fluid is supplied to the pair of connectors 90, the cutting fluid flows into the pair of nozzles 92 and is sprayed from the cutting fluid supply port toward the front and back surfaces of the cutting tool 58.

[0063] The cutting tool 58 attached to the tip of the spindle 64 rotates around a rotation axis roughly parallel to the Y-axis direction by power transmitted from a rotation drive source (not shown) via the spindle 64 and the blade mount 66. The rotating cutting tool 58 is caused to cut into the workpiece 11 (see FIG. 2), thereby cutting the workpiece 11.

[0064] While cutting the workpiece 11, cutting fluid is supplied to the workpiece 11 and the cutting tool 58. This cools the workpiece 11 and the cutting tool 58 and washes away chips (cutting chips) generated by cutting the workpiece 11. However, it is also possible to cut the workpiece 11 by dry machining without supplying cutting fluid.

[0065] When mounting the cutting tool 58 on the cutting unit 20a, the orientation of the cutting tool 58 can be selected, thereby allowing the cutting tool 58 to rotate in a desired direction relative to the orientation of the cutting portion 60. Furthermore, if the spindle 64 is bidirectionally rotatable, the cutting tool 58 can be rotated in a desired direction by switching the rotation direction of the spindle 64.

[0066] Fig. 5(A) is a front view showing cutting tool 58 rotating in the forward direction. When cutting tool 58 is attached to cutting unit 20a in the orientation shown in Fig. 5(A) and spindle 64 (see Fig. 4) is rotated, cutting tool 58 rotates in the forward direction (direction indicated by arrow A). At this time, cutting tool 58 rotates such that first surface 60d of each cutting portion 60 is positioned forward of second surface 60e in the direction of rotation of cutting tool 58.

[0067] When the cutting tool 58 is rotated in the forward direction and brought close to the workpiece 11, the cutting tool 58 cuts into the workpiece 11 so that the first surface 60d collides with the workpiece 11. As a result, the first surface 60d mainly comes into contact with the workpiece 11 and cuts away the workpiece 11, and the cutting chips are sent forward in the rotation direction of the cutting tool 58 by the first surface 60d. In other words, when the cutting tool 58 is rotating in the forward direction, the first surface 60d corresponds to the rake face, and the second surface 60e corresponds to the flank face.

[0068] Figure 5(B) is a front view showing the cutting tool 58 rotating in the reverse direction. When the cutting tool 58 is attached to the cutting unit 20a in the orientation shown in Figure 5(B) and the spindle 64 (see Figure 4) is rotated, the cutting tool 58 rotates in the reverse direction (the direction indicated by arrow B). At this time, the cutting tool 58 rotates such that the second surface 60e of each cutting portion 60 is positioned forward of the first surface 60d in the direction of rotation of the cutting tool 58.

[0069] When the cutting tool 58 is rotated in the reverse direction and brought close to the workpiece 11, the cutting tool 58 cuts into the workpiece 11 so that the second surface 60e collides with the workpiece 11. As a result, the second surface 60e mainly comes into contact with the workpiece 11 and cuts away the workpiece 11, and the cutting chips are sent forward in the rotation direction of the cutting tool 58 by the second surface 60e. In other words, while the cutting tool 58 is rotating in the reverse direction, the second surface 60e corresponds to the rake face, and the first surface 60d corresponds to the flank face.

[0070] Next, a specific example of a method for processing the workpiece 11 using the cutting tool 58 will be described. As an example, the following describes a case where the workpiece 11 is divided into a plurality of chips by cutting the workpiece 11 with the cutting tool 58.

[0071] First, the workpiece 11 is held by the chuck table 10 (holding step). FIG. 6 is a partial cross-sectional front view showing the cutting device 2 holding the workpiece 11 on the chuck table 10.

[0072] In the holding step, first, the workpiece 11 is placed on the chuck table 10. For example, the workpiece 11 is placed on the chuck table 10 so that the front surface 11a is exposed upward and the back surface 11b (the tape 19 side) faces the holding surface 10a. The frame 17 is also fixed by a plurality of clamps 18. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 10a, the workpiece 11 is suction-held by the chuck table 10 via the tape 19.

[0073] Next, the cutting tool 58 is rotated to cut into the workpiece 11 held by the chuck table 10, thereby cutting the workpiece 11 (cutting step). As an example, a case will be described in which the workpiece 11 is divided into a plurality of chips by so-called down-cutting, in which the cutting tool 58 cuts from the upper side (front surface 11a side) of the workpiece 11 toward the lower side (back surface 11b side). Fig. 7(A) is a partial cross-sectional front view showing a cutting device 2 that cuts the workpiece 11 by down-cutting.

[0074] In the cutting process, first, the chuck table 10 is rotated to align the length direction of one side (one side surface) of the workpiece 11 with the X-axis direction. Then, the positions of the chuck table 10 and the cutting unit 20a are adjusted so that the cutting tool 58 is positioned to the side of the workpiece 11. Furthermore, the height position of the cutting unit 20a is adjusted so that the lower end of the cutting tool 58 is positioned below the lower surface (rear surface 11b) of the workpiece 11 and above the lower surface (holding surface 10a) of the tape 19.

[0075] Next, the cutting tool 58 is rotated. In this embodiment, the cutting tool 58 is attached to the cutting unit 20a so as to rotate in the opposite direction (see FIG. 5(B)). Therefore, in the cutting process, the cutting tool 58 rotates so that the second surface 60e of each cutting portion 60 is positioned forward of the first surface 60d in the direction of rotation of the cutting tool 58. As a result, the second surface 60e becomes the rake face of the cutting portion 60, and the first surface 60d becomes the flank face of the cutting portion 60. The rotational speed of the cutting tool 58 is set, for example, to 3,000 rpm or more and 40,000 rpm or less, preferably 9,000 rpm or more and 11,000 rpm or less.

[0076] Next, with the cutting tool 58 rotating in the reverse direction, the chuck table 10 is moved toward the cutting tool 58 along the X-axis direction, and the workpiece 11 and the cutting tool 58 are moved relatively along the X-axis direction (processing feed). The processing feed speed is set, for example, at 5 mm / s or more and 100 mm / s or less, preferably at 5 mm / s or more and 15 mm / s or less. As a result, the cutting tool 58 cuts into the workpiece 11 to a cutting depth that exceeds the thickness of the workpiece 11, and cuts the workpiece 11 from the upper side (the front surface 11a side) to the lower side (the back surface 11b side). As a result, a kerf (cut) is formed in the workpiece 11 along the X-axis direction, and the workpiece 11 is divided.

[0077] Next, the cutting unit 20a is moved a predetermined amount in the Y-axis direction (indexing feed), and the workpiece 11 is cut in the same manner. By repeating this operation, a plurality of kerfs that are approximately parallel to each other are formed in the workpiece 11 along the first direction.

[0078] Next, the chuck table 10 is rotated by 90°, and the workpiece 11 is cut in the same manner. As a result, a plurality of kerfs that are approximately parallel to each other are formed in the workpiece 11 along a second direction that is perpendicular to the first direction.

[0079] When the workpiece 11 is cut as described above, lattice-shaped kerfs are formed in the workpiece 11, and the workpiece 11 is divided into a plurality of rectangular chips (individual pieces). These chips are used, for example, to manufacture multilayer ceramic chip capacitors.

[0080] 7(B) is a front view showing the cutting edge 60 of the cutting tool 58 that cuts the workpiece 11 by down-cutting. When the cutting tool 58 is rotated in the reverse direction to cut into the workpiece 11, the second surface 60e of the cutting edge 60 comes into contact with the workpiece 11 and cuts away the workpiece 11 from the upper side (the front surface 11a side) to the lower side (the back surface 11b side). In addition, the second surface 60e (the rake face) sends cutting chips forward (downward) in the direction of rotation of the cutting tool 58.

[0081] In this way, when the cutting tool 58 is rotated in the reverse direction to cut into the workpiece 11, the second surface 60e, which is inclined rearward in the rotational direction relative to the radial direction of the cutting tool 58, comes into contact with the workpiece 11. This reduces the processing load applied to the workpiece 11 when the cutting tool 58 comes into contact with the workpiece 11. As a result, the regular lamination of the metal layers 13 and the ceramic layers 15 on the cut surface (cut surface) of the workpiece 11 is less likely to be disrupted, improving the processing quality of the workpiece 11. In particular, when the second surface 60e is a curved surface formed so as to be curved in the opposite direction to the first surface 60d, the processing load is likely to be reduced.

[0082] In the cutting process, the workpiece 11 can also be divided into a plurality of chips by so-called up-cutting, in which the cutting tool 58 cuts from the lower side (back surface 11b side) of the workpiece 11 toward the upper side (front surface 11a side). Fig. 8(A) is a partial cross-sectional front view showing the cutting device 2 that cuts the workpiece 11 by up-cutting.

[0083] Even when cutting the workpiece 11 by up-cutting, the cutting tool 58 is rotated in the reverse direction while being fed for processing. As a result, the cutting tool 58 cuts into the workpiece 11 to a cutting depth that exceeds the thickness of the workpiece 11, and cuts the workpiece 11 from the lower side (the rear surface 11b side) toward the upper side (the front surface 11a side).

[0084] 8(B) is a front view showing the cutting edge 60 of the cutting tool 58 that cuts the workpiece 11 by up-cutting. When the cutting tool 58 is rotated in the reverse direction to cut into the workpiece 11, the second surface 60e of the cutting edge 60 comes into contact with the workpiece 11 and cuts away the workpiece 11 from the lower side (the rear surface 11b side) toward the upper side (the front surface 11a side). In addition, cutting chips are sent forward (upward) in the direction of rotation of the cutting tool 58 by the second surface 60e (the rake face).

[0085] As described above, in the method for processing a workpiece according to this embodiment, the cutting tool 58 having the multiple cutting edges 60 is rotated in the reverse direction and cuts into the workpiece 11 to cut the workpiece 11. This allows the second surface 60e, which is an inclined surface that corresponds to the flank when the cutting tool 58 is rotated in the normal forward direction, to function as a rake face when cutting the workpiece 11 having a layered structure. As a result, the processing load on the workpiece 11 is alleviated, making it less likely that the layered structure of the workpiece 11 will collapse, and improving processing quality.

[0086] The structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention.

[0087] Next, the results of evaluating the processing quality when the workpiece 11 was processed using the workpiece processing method according to the present invention will be described. In this evaluation, the workpiece 11 was cut with the cutting tool 58 rotating in the forward direction and with the cutting tool 58 rotating in the reverse direction, and the cut surface (cut surface) formed by the cutting was observed under a microscope.

[0088] The workpiece 11 used was a rectangular sample (length 130 mm, width 130 mm) in which metal layers and unsintered ceramic layers were alternately laminated. Five types of metal saws A, B, C, D, and E (outer diameter 57 mm, inner diameter 40 mm, thickness of the cutting portion 60 0.08 mm) with different shapes of the cutting portion 60 were used as the cutting tools 58. Details of the shapes of the metal saws A, B, C, D, and E are shown in Table 1. The rake angle in Table 1 corresponds to the angle of the first surface 60d of the cutting portion 60 (see FIG. 3(B) and other figures). The clearance angle in Table 1 corresponds to the angle of the second surface 60e of the cutting portion 60 (see FIG. 3(B) and other figures).

[0089] [Table 1]

[0090] Then, the workpiece 11 was cut with the metal saws A, B, C, D, and E rotating in the forward direction (see FIG. 5(A)) and in the reverse direction (see FIG. 5(B)). The processing feed rate was set to 10 mm / s, and the rotation speed of the metal saws A, B, C, D, and E was set to 10,000 rpm. The workpiece 11 was then cut using dry processing without using cutting fluid, and the workpiece 11 was divided into multiple rectangular chips (2 mm long, 1 mm wide).

[0091] The cut surface of the chip was then observed under a scanning electron microscope (magnification 5000x) to confirm whether the laminated structure of the metal layer and ceramic layer could be observed in the cross section of the chip. The observation results of the laminated structure are shown in Table 2.

[0092] [Table 2]

[0093] When the workpiece 11 was cut with metal saws A, B, D, and E rotating in the forward direction, the laminated structure could not be observed on the cut surface. Furthermore, when the workpiece 11 was cut with metal saw C rotating in the forward direction, the laminated structure could be slightly observed on part of the cut surface, but the boundary between the metal layer and the ceramic layer was unclear. From these observation results, it was confirmed that when the cutting tool 58 is rotated in the forward direction, a large processing load is applied to the workpiece 11, and the laminated structure is likely to collapse on the cut surface.

[0094] On the other hand, when the workpiece 11 was cut using metal saws A, B, C, D, and E rotating in the opposite direction, the generally parallel stacked metal and ceramic layers were clearly visible in the SEM images, and a clear stacked structure was confirmed on the cut surface. In particular, when metal saw D, which has a smaller number of cutting edges 60, was used, the stacked structure of the metal and ceramic layers was maintained almost without collapse on the cut surface. This result is presumably due to the fact that rotating the cutting tool 58 in the opposite direction reduced the processing load on the workpiece 11, making it less likely for the stacked structure to collapse.

[0095] From the above evaluation results, it was confirmed that when the method for processing a workpiece according to the present invention is used, the processing load on the workpiece 11 is reduced, and the workpiece 11 can be cut and divided without damaging the regular laminated structure of the metal layer and the ceramic layer. [Explanation of symbols]

[0096] 11 Workpiece 11a Surface (first side) 11b Back side (2nd side) 13 Metal layer 15 ceramic layers 17 frames 17a aperture 19 Tape (dicing tape) 2 Cutting equipment 4 Foundation 4a,4b,4c opening 6 Cassette support stand 8 cassettes 10 Chuck table (holding table) 10a Holding surface 12 Moving mechanism 14 Table Cover 16 Dustproof and water-resistant cover 18 Clamp 20a, 20b Cutting unit 22 Support structure 24a,24b Moving mechanism 26 Y-axis guide rail 28a, 28b Y-axis moving plate 30a, 30b Y-axis ball screw 32 Y-axis pulse motor 34a, 34b Z-axis guide rail 36a, 36b Z-axis moving plate 38a, 38b Z-axis ball screw 40a, 40b Z-axis pulse motor 42 Imaging unit 44 Cleaning Unit 46 Spinner Table 46a Holding surface 48 nozzles 50 Cover 52 Display unit (display unit, display device) 54 alarm unit (alarm unit, alarm device) 56 Control unit (control unit, control device) 58 Cutting tools (cutting blades) 58a aperture 60 Blade (protrusion, convex part, saw blade) 60a tip 60b 1st proximal end 60c 2nd proximal end 60d 1st page 60e 2nd side 62 Housing 64 spindles 64a aperture 64b screw groove 66 Blade Mount 66a aperture 68 Flange 68a surface 68b Convex part 70 Boss part (support shaft) 70a thread groove 72 Fixing bolt 74 Flange (pressing flange) 74a aperture 76 Fixing nut 78 Blade Cover 80 Main body 82 Slide cover 84 Air Cylinder 86 Connector 88 Connector 90 Connector 92 nozzles

Claims

1. A method for processing a workpiece, in which a workpiece including a laminated metal layer and a ceramic layer is cut with a cutting tool, comprising: The cutting tool has a plurality of cutting edges on its outer periphery, the blade portion includes a distal end, a first proximal end, a second proximal end, a first surface connected to the distal end and the first proximal end, and a second surface connected to the distal end and the second proximal end; a distance between the tip and the first base end is shorter than a distance between the tip and the second base end; a holding step of holding the workpiece by a chuck table; a cutting step of rotating the cutting tool so that the second surface is positioned forward of the first surface in the direction of rotation, and cutting the workpiece held by the chuck table to cut the workpiece.

2. 2. The method for machining a workpiece according to claim 1, wherein the second surface is a curved surface that curves in a direction opposite to the first surface.

Images