JP7803777B2 - Processing method of workpiece - Google Patents

Description

The present invention relates to a method for processing a workpiece by cutting the workpiece with a cutting tool.

Device chips each containing a device are manufactured by dividing and singulating a semiconductor wafer on which multiple devices are formed. Furthermore, a package substrate is obtained by mounting multiple device chips on a base substrate and covering the mounted device chips with a resin encapsulant (mold resin). Package devices each containing multiple packaged device chips are manufactured by dividing and singulating this package substrate. Device chips and package devices are incorporated into various electronic devices such as mobile phones and personal computers.

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 the cutting process on the workpiece. The cutting unit has a built-in spindle, the tip of which is fitted with an annular cutting tool (cutting blade). The workpiece is held on the chuck table and the cutting tool is rotated as it cuts into the workpiece, cutting and dividing it.

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-shaped 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.

Japanese Unexamined Patent Publication No. 4-179505

Cutting tools (cutting blades) equipped with saw-tooth cutting edges like those 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 singulated with the cutting tool described above to obtain chips that include metal and ceramic layers. These chips can then be 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.

However, when a workpiece is cut with a cutting tool equipped with a cutting edge, the steep rake face comes into contact with the workpiece while rotating at high speed. As a result, a large processing load is placed on the workpiece, and the regular layering of the metal and ceramic layers on the cut surface (cut surface) of the chip that has been cut can be disrupted. This leads to a problem of a deterioration in the processing quality of the workpiece and a decrease in the yield of chips obtained by dividing the workpiece.

The present invention was made in consideration of these problems, and aims to provide a method for processing workpieces that can improve the processing quality of workpieces that include multiple stacked layers.

One aspect of the present invention provides a method for machining a workpiece, the workpiece including laminated metal layers and ceramic layers, using a cutting tool. The cutting tool has 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 includes: a holding step of holding the workpiece on a chuck table; and a cutting step of rotating the cutting tool so that the second surface is positioned forward of the first surface in the rotational direction, thereby cutting the workpiece held by the chuck table.

Preferably, the second surface is a curved surface that curves in the opposite direction to the first surface.

In one aspect of the present invention, a method for machining a workpiece involves rotating a cutting tool equipped with multiple cutting edges in the reverse direction while cutting into the workpiece, thereby cutting 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 layered structure. As a result, the machining load on the workpiece is reduced, making it less likely for the layered structure of the workpiece to collapse, and improving machining quality.

FIG. FIG. FIG. 3A is a front view showing the cutting tool, and FIG. 3B is a front view showing the cutting part of the cutting tool. FIG. 2 is an exploded perspective view showing the cutting unit. FIG. 5A is a front view showing a cutting tool that rotates in the forward direction, and FIG. 5B is a front view showing a cutting tool that rotates in the reverse direction. FIG. 2 is a partial cross-sectional front view showing the cutting device in which a workpiece is held by a chuck table. FIG. 7A is a partial cross-sectional front view showing a cutting device that cuts a workpiece by down cutting, and FIG. 7B is a front view showing a cutting edge of a cutting tool that cuts a workpiece by down cutting. FIG. 8A is a partial cross-sectional front view showing a cutting device that cuts a workpiece by up-cutting, and FIG. 8B is a front view showing a cutting tool blade that cuts a workpiece by up-cutting.

An embodiment of the present invention will now be described with reference to the accompanying drawings. First, an example configuration of a cutting device that can be used in the workpiece processing method according to this embodiment will be described. Figure 1 is a perspective view showing a cutting device 2 that performs cutting processing on a workpiece 11. Note that in Figure 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-back direction) are mutually perpendicular. Furthermore, the Z-axis direction (vertical direction, up-down direction, height direction) is a direction perpendicular to the X-axis and Y-axis directions.

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 the front corner of the base 4. Inside the opening 4a, a cassette support table 6 is provided that is raised and lowered by an elevation mechanism (not shown). A cassette 8 that can hold multiple workpieces 11, which are the objects to be processed by the cutting device 2, is placed on the cassette support table 6. Note that in Figure 1, the outline of the cassette 8 is indicated by a two-dot chain line.

Figure 2 is a perspective view showing the workpiece 11. The workpiece 11 is a plate- or sheet-like member (laminate) including multiple 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 multiple metal layers 13 and multiple ceramic layers 15. Note that for ease of explanation, the thicknesses of the metal layers 13 and ceramic layers 15 are exaggerated in Figure 2.

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

For example, the workpiece 11 is formed by stacking and pressing multiple sheet-shaped dielectrics (green sheets) made of pre-sintered ceramic and coated with electrode paste. There are no restrictions on the thickness or number of the metal layers 13 and ceramic layers 15 to be stacked.

By cutting and dividing the workpiece 11 using a cutting device 2 (see Figure 1), chips of the desired size are obtained, each containing an individual metal layer 13 and ceramic layer 15. These chips are then subjected to firing, external electrode formation, plating, and other processes to produce multilayer ceramic capacitors, with the metal layer 13 serving as an internal electrode and the ceramic layer 15 serving as a dielectric. However, the structure, material, etc. of the workpiece 11 can be modified as appropriate depending on the intended use of the workpiece 11.

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 has a circular opening 17a at the center that penetrates the frame 17 in the thickness direction. The diameter of the opening 17a is greater than the length of each side of the workpiece 11.

Tape (dicing tape) 19 is attached to the workpiece 11 and frame 17. For example, 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 also be an ultraviolet-curing resin that hardens when exposed to ultraviolet light.

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 allows the workpiece 11 to be supported by the frame 17 via the tape 19. The workpiece 11, supported by the frame 17, is then placed in the cassette 8 shown in Figure 1.

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 that holds the 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 that holds 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), etc., provided inside the chuck table 10.

A movement mechanism 12 that moves the chuck table 10 along the X-axis direction is connected to the chuck table 10. For example, the movement mechanism 12 is a ball screw type movement 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.

The movement mechanism 12 also includes a flat table cover 14 that surrounds the chuck table 10. Furthermore, accordion-shaped dust- and drip-proof covers 16 that are expandable and contractible along the X-axis direction are provided on both sides of the table cover 14. The table cover 14 and dust- and drip-proof covers 16 are installed to cover the components of the movement mechanism 12 (X-axis ball screw, X-axis pulse motor, etc.) housed inside the opening 4b.

A rotary drive source (not shown), such as a motor, is connected to the chuck table 10, which rotates the chuck table 10 around a rotation axis generally parallel to the Z-axis direction. Additionally, multiple clamps 18 are provided around the periphery of the chuck table 10 to grip and secure the frame 17 supporting the workpiece 11.

A transport mechanism (not shown) is provided near the openings 4a and 4b to transport the workpiece 11 between the cassette 8 and the chuck table 10. The workpiece 11 is pulled out of the cassette 8 by the transport mechanism and transported to the chuck table 10.

Cutting units 20a and 20b that cut the workpiece 11 are provided above the chuck table 10. A gate-shaped support structure 22 that supports the cutting units 20a and 20b is also located on the top surface of the base 4, straddling the opening 4b.

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

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 back side of the Y-axis moving plate 28a. A Y-axis ball screw 30a, which is arranged generally parallel to the Y-axis guide rails 26, is threadedly engaged with this nut portion. A Y-axis pulse motor 32, which rotates the Y-axis ball screw 30a, is connected to the 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.

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 positioned generally parallel to the Z-axis guide rails 34a, is threadedly engaged with this nut portion. A Z-axis pulse motor 40a, which rotates the Z-axis ball screw 38a, is connected to the end of the Z-axis ball screw 38a.

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 bottom of the Z-axis moving plate 36a.

Similarly, the movement mechanism 24b includes a flat Y-axis movement plate 28b. The Y-axis movement plate 28b is slidably mounted on a pair of Y-axis guide rails 26. A nut portion (not shown) is provided on the back side of the Y-axis movement plate 28b. A Y-axis ball screw 30b, which is arranged generally 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 connected to the end of the Y-axis ball screw 30b. When the Y-axis pulse motor rotates the Y-axis ball screw 30b, the Y-axis movement plate 28b moves in the Y-axis direction along the Y-axis guide rails 26.

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 positioned generally parallel to the Z-axis guide rails 34b, is threadedly engaged with this nut portion. A Z-axis pulse motor 40b, which rotates the Z-axis ball screw 38b, is connected to the end of the Z-axis ball screw 38b.

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 bottom of the Z-axis moving plate 36b.

An imaging unit 42 is provided adjacent to the cutting unit 20a to capture images of subjects 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 selected appropriately depending on the material of the workpiece 11, etc. For example, a visible light camera or an infrared camera can be used as the imaging unit 42. The images captured by the imaging unit 42 are used to align the workpiece 11 with the cutting units 20a and 20b, etc.

A circular opening 4c is provided behind the opening 4b. Inside the opening 4c, a cleaning unit 44 is provided to clean the workpiece 11. 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.

The upper surface of the spinner table 46 is a flat surface 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), etc. provided inside the spinner table 46. In addition, a rotational drive source (not shown) such as a motor is connected to the spinner table 46, which rotates the spinner table 46 around a rotation axis roughly parallel to the Z-axis direction.

A nozzle 48 is positioned above the spinner table 46 to supply cleaning fluid. For example, the cleaning fluid may be a liquid (such as pure water) or a mixed fluid containing a liquid (such as pure water) and a gas (such as air). With the workpiece 11 held by the spinner table 46, the spinner table 46 is rotated while cleaning fluid is supplied from the nozzle 48 toward the workpiece 11, thereby cleaning the workpiece 11.

A transport mechanism (not shown) is provided near the openings 4b and 4c to transport 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 transported from the chuck table 10 to the spinner table 46 by the transport mechanism and cleaned. After cleaning, the workpiece 11 is then loaded into the cassette 8 by the transport mechanism.

A cover 50 is provided on the upper side of the base 4 to cover the components mounted on the base 4. In Figure 1, the outline of the cover 50 is shown by a two-dot chain line.

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 types of 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 into the cutting device 2, and the operator can input information into the cutting device 2 by touching the display unit 52. In other words, the display unit 52 functions as a user interface.

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 are no restrictions 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.

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 movement mechanism 12, the clamp 18, the cutting units 20a and 20b, the movement mechanisms 24a and 24b, the imaging unit 42, the cleaning unit 44, the display unit 52, the alarm unit 54, etc.).

The control unit 56 controls the operation of each component of the cutting device 2 by outputting control signals to each component, thereby 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 the calculations necessary to operate the cutting device 2, and memory such as ROM (Read Only Memory) and RAM (Random Access Memory) that store various information (data, programs, etc.) used to operate the cutting device 2.

Each of the cutting units 20a and 20b is fitted with an annular cutting tool (cutting blade) 58 that cuts the workpiece 11. This positions the pair of cutting tools 58 facing each other. Each of the cutting units 20a and 20b then cuts the workpiece 11 by rotating the cutting tool 58 and cutting into the workpiece 11 held by the chuck table 10. However, the cutting device 2 may be equipped with only one cutting unit.

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

When cutting tool 58 is a metal saw made of cemented carbide, the metal contained in the cemented carbide can be selected as appropriate. For example, cutting tool 58 may be 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, etc.). WC-Co alloys containing tungsten carbide (WC) and cobalt are particularly suitable as materials for cutting tool 58 because they exhibit high hardness over a wide temperature range and have excellent mechanical strength.

However, there are no restrictions on the material of the cutting tool 58. For example, the 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, ceramic, resin, or the like.

A circular opening 58a is provided in the center of the cutting tool 58, penetrating the cutting tool 58 in the thickness direction. Furthermore, 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 to be roughly the same shape and are arranged at roughly equal intervals around the periphery of the cutting tool 58.

Figure 3(B) is a front view showing the blade portion 60 of the cutting tool 58. The blade portion 60 has a tip 60a, a first base end 60b, and a second base end 60c. The tip 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 tip 60a, first base end 60b, and second base end 60c are each formed linearly along the thickness direction of the cutting tool 58.

The blade portion 60 also has a first surface 60d connected to the tip 60a and the first base end 60b, and a second surface 60e connected to the tip 60a and the second base end 60c. The distance a between the tip 60a and the first base end 60b is shorter than the distance b between the tip 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. In other words, 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°).

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

The cutting tool 58 is attached to the cutting units 20a and 20b (see Figure 1). The cutting units 20a and 20b are described in detail below. Note that while an example configuration of the cutting unit 20a is described here, the cutting unit 20b can also be configured in the same way.

Figure 4 is an exploded perspective view showing the cutting unit 20a. The cutting unit 20a includes a columnar housing 62 connected to the movement mechanism 24a (see Figure 1). The housing 62 contains 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 rotational drive source (not shown), such as a motor, is connected to the base (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.

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 the surface 68a of the flange 68. The blade mount 66 also has an opening 66a that passes through the center of the flange 68 and boss 70. The blade mount 66 is fixed to the tip of the spindle 64 by inserting a fixing bolt 72 through the opening 66a of the blade mount 66 and into the opening 64a of the spindle 64, and tightening it into the thread groove 64b.

A ring-shaped protrusion 68b protruding from the surface 68a of the outer periphery of the flange portion 68 is provided along the outer edge of the flange portion 68. The tip surface of the protrusion 68b is a flat surface roughly parallel to the surface 68a, and forms a support surface that supports the cutting tool 58. A thread groove 70a is also formed on the outer periphery of the boss portion 70.

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

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 flange 74 are supported by the blade mount 66. In this state, when the annular fixing nut 76 is threaded into the thread groove 70a of the boss portion 70 and tightened, the cutting tool 58 and flange 74 are fixed to the blade mount 66. As a result, the cutting tool 58 is clamped between the flange portion 68 and the flange 74 and attached to the tip of the spindle 64.

The housing 62 is also fitted with 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 comprises a main body 80 fixed to the tip of the housing 62 and a slide cover 82 that can slide along the X-axis direction to move towards and away from the main body 80.

The slide cover 82 is connected to the main body 80 via an air cylinder 84. When air is supplied to a connector 86 attached to the main body 80, the air cylinder 84 is actuated, causing the slide cover 82 to slide 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.

The main body 80 is provided with a connector 88 through which a liquid (cutting fluid) such as pure water is supplied, and a cutting fluid supply channel (not shown) connected to the connector 88. The tip of the cutting fluid supply channel 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 channel and is supplied to the outer periphery of the cutting tool 58.

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 positioned 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.

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 rotary drive source (not shown) via the spindle 64 and blade mount 66. The rotating cutting tool 58 is then caused to cut into the workpiece 11 (see Figure 2), thereby cutting the workpiece 11.

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

When attaching the cutting tool 58 to the cutting unit 20a, the orientation of the cutting tool 58 can be selected, allowing the cutting tool 58 to rotate in the desired direction relative to the orientation of the cutting blade 60. Furthermore, if the spindle 64 is bidirectionally rotatable, the cutting tool 58 can be rotated in the desired direction by switching the rotation direction of the spindle 64.

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

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 direction of rotation 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 relief face.

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 so that the second surface 60e of each cutting edge 60 is positioned further forward in the direction of rotation of the cutting tool 58 than the first surface 60d.

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 direction of rotation 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 relief face.

Next, a specific example of a workpiece processing method in which the workpiece 11 is processed using a cutting tool 58 will be described. As an example, the following describes a case in which the workpiece 11 is divided into multiple chips by cutting the workpiece 11 with the cutting tool 58.

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

In the holding process, 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 in place by multiple 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.

Next, the cutting tool 58 is rotated and cuts into the workpiece 11 held by the chuck table 10, thereby cutting the workpiece 11 (cutting process). As an example, we will explain a case where the workpiece 11 is divided into multiple chips by so-called down-cutting, in which the cutting tool 58 cuts from the top side (surface 11a side) of the workpiece 11 toward the bottom side (back surface 11b side). Figure 7(A) is a partial cross-sectional front view showing a cutting device 2 that cuts the workpiece 11 by down-cutting.

In the cutting process, first, the chuck table 10 is rotated to align the length direction of one side (one side) of the workpiece 11 with the X-axis direction. The positions of the chuck table 10 and cutting unit 20a are then 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 bottom end of the cutting tool 58 is positioned below the bottom surface (back surface 11b) of the workpiece 11 and above the bottom surface (holding surface 10a) of the tape 19.

Next, the cutting tool 58 is rotated. In this embodiment, the cutting tool 58 is attached to the cutting unit 20a so that it rotates in the opposite direction (see Figure 5(B)). Therefore, during the cutting process, the cutting tool 58 rotates so that the second surface 60e of each cutting portion 60 is positioned further forward in the direction of rotation of the cutting tool 58 than the first surface 60d. 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, between 3,000 rpm and 40,000 rpm, and preferably between 9,000 rpm and 11,000 rpm.

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 cutting tool 58 are moved relatively along the X-axis direction (machining feed). The machining feed rate is set, for example, between 5 mm/s and 100 mm/s, preferably between 5 mm/s and 15 mm/s. As a result, the cutting tool 58 cuts into the workpiece 11 to a depth of cut that exceeds the thickness of the workpiece 11, cutting the workpiece 11 from the upper side (surface 11a side) to the lower side (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.

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 process, multiple kerfs that are generally parallel to one another are formed in the workpiece 11 along the first direction.

Next, the chuck table 10 is rotated 90°, and the workpiece 11 is cut using the same procedure. As a result, multiple kerfs that are roughly parallel to each other are formed in the workpiece 11 along a second direction perpendicular to the first direction.

When the workpiece 11 is cut as described above, a lattice-like kerf is formed in the workpiece 11, and the workpiece 11 is divided into multiple rectangular chips (individual pieces). These chips are used, for example, to manufacture multilayer ceramic chip capacitors.

Figure 7 (B) is a front view showing the blade portion 60 of the cutting tool 58 that cuts the workpiece 11 using 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 blade portion 60 comes into contact with the workpiece 11 and cuts away the workpiece 11 from the top (front surface 11a side) to the bottom (back surface 11b side). Furthermore, the second surface 60e (rake face) sends cutting chips forward (downward) in the direction of rotation of the cutting tool 58.

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 direction of rotation 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 layer 13 and the ceramic layer 15 on the cut surface (cut surface) of the workpiece 11 is less likely to collapse, improving the processing quality of the workpiece 11. In particular, the processing load is likely to be reduced when the second surface 60e is a curved surface formed so as to be curved in the opposite direction from the first surface 60d.

In the cutting process, the workpiece 11 can also be divided into multiple chips by up-cutting, in which the cutting tool 58 cuts from the bottom side (back surface 11b side) of the workpiece 11 toward the top side (front surface 11a side). Figure 8(A) is a partial cross-sectional front view showing a cutting device 2 that cuts the workpiece 11 by up-cutting.

Even when cutting the workpiece 11 using up-cutting, the cutting tool 58 is rotated in the reverse direction while the feed is performed. This allows the cutting tool 58 to cut into the workpiece 11 to a depth that exceeds the thickness of the workpiece 11, cutting the workpiece 11 from the bottom (back surface 11b side) to the top (front surface 11a side).

Figure 8 (B) is a front view showing the cutting edge 60 of the cutting tool 58, which cuts the workpiece 11 using an up-cut method. 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 bottom (back surface 11b side) to the top (front surface 11a side). Furthermore, the second surface 60e (rake face) sends cutting chips forward (upward) in the direction of rotation of the cutting tool 58.

As described above, in the method for processing a workpiece according to this embodiment, a cutting tool 58 equipped with 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 equivalent to the clearance surface when the cutting tool 58 is rotated in the normal forward direction, to function as a rake face when cutting the workpiece 11, which has a layered structure. As a result, the processing load on the workpiece 11 is alleviated, making it less likely for the layered structure of the workpiece 11 to collapse, and improving processing quality.

The structures, methods, etc. related to the above embodiments can be modified as appropriate without departing from the scope of the present invention.

Next, we will explain the results of an evaluation of the processing quality when the workpiece 11 was processed using the workpiece processing method of the present invention. 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.

The workpiece 11 used was a rectangular sample (length 130 mm, width 130 mm) consisting of alternating layers of metal and unsintered ceramic. The cutting tools 58 used were five types of metal saws A, B, C, D, and E (outer diameter 57 mm, inner diameter 40 mm, thickness of the cutting edge 60 0.08 mm) with different cutting edge 60 shapes. 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 edge 60 (see Figure 3(B) and other figures). The clearance angle in Table 1 corresponds to the angle of the second surface 60e of the cutting edge 60 (see Figure 3(B) and other figures).

Then, the workpiece 11 was cut with metal saws A, B, C, D, and E rotating in the forward direction (see Figure 5(A)) and the reverse direction (see Figure 5(B)). The processing feed rate was set to 10 mm/s, and the rotation speed of 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).

Then, the cut surface of the chip was observed with 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.

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. These observation results confirmed that when the cutting tool 58 is rotated in the forward direction, a large processing load is applied to the workpiece 11, making it easy for the laminated structure to collapse on the cut surface.

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 fewer cutting edges 60, was used, the stacked structure of the metal and ceramic layers was maintained with almost no 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.

The above evaluation results confirmed that using the workpiece processing method according to the present invention reduces the processing load on the workpiece 11 and enables cutting and dividing the workpiece 11 without damaging the regular layered structure of the metal and ceramic layers.

11 Workpiece 11a Surface (first surface)
11b Back side (second side)
13 Metal layer 15 Ceramic layer 17 Frame 17a Opening 19 Tape (dicing tape)
2 Cutting device 4 Base 4a, 4b, 4c Opening 6 Cassette support base 8 Cassette 10 Chuck table (holding table)
10a Holding surface 12 Moving mechanism 14 Table cover 16 Dust-proof and drip-proof 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 Nozzle 50 Cover 52 Display unit (display section, display device)
54 alarm unit (alarm section, alarm device)
56 Control unit (control unit, control device)
58 Cutting tools (cutting blades)
58a Opening 60 Blade portion (protrusion, convex portion, saw blade)
60a Tip 60b First base end 60c Second base end 60d First surface 60e Second surface 62 Housing 64 Spindle 64a Opening 64b Thread groove 66 Blade mount 66a Opening 68 Flange portion 68a Surface 68b Convex portion 70 Boss portion (support shaft)
70a Thread groove 72 Fixing bolt 74 Flange (pressing flange)
74a Opening 76 Fixing nut 78 Blade cover 80 Main body 82 Slide cover 84 Air cylinder 86 Connector 88 Connector 90 Connector 92 Nozzle

Claims (2)

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. 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.