Cutting method and cutting device

Abstract

To reduce the amount of burrs remaining on a division schedule line of a workpiece when cutting the workpiece with a single cutting blade, without using a covering member.SOLUTION: A cutting method comprises: a first cutting step of cutting a workpiece, held on a holding table, along a predetermined division schedule line of the workpiece with a cutting blade; and a second cutting step of setting the thickness of the cutting blade to a second thickness greater than the first thickness of the cutting blade in the first cutting step, and cutting the workpiece along the division schedule line with the cutting blade having the second thickness so as to remove at least burrs generated on the division schedule line in the first cutting step. A difference between the first thickness and the second thickness is obtained by applying an external stimulus to the cutting blade in the first cutting step or the second cutting step.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a cutting method for cutting a workpiece held on a holding table with a cutting blade, and a cutting device for implementing the cutting method. [Background technology]

[0002] When manufacturing a semiconductor package such as a QFN (Quad Flat Non-lead package) in which semiconductor device chips are covered with molding resin, for example, a workpiece is created in which multiple semiconductor device chips arranged on a semiconductor package substrate are covered with molding resin, and then the workpiece is cut with a cutting device to divide it into individual semiconductor device chips.

[0003] Metal electrodes exist along the planned dividing lines of this workpiece. Metal materials are generally ductile and malleable, so metal burrs are generated when the workpiece is cut with a cutting device. If burrs remain on the semiconductor packages after singulation, they may cause mounting defects when the semiconductor packages are mounted on printed circuit boards or other devices.

[0004] Therefore, for example, in order to suppress the occurrence of burrs, a method is known in which a covering member such as adhesive tape is attached to the surface of the workpiece where the metal electrode is exposed, and then a first cutting groove having a depth that does not fully cut the metal electrode is formed with a first cutting blade, and then the covering member is peeled off and the center of the first cutting groove is further cut with a second cutting blade having a blade thickness thinner than the first cutting blade, thereby singulating the workpiece into semiconductor packages (see, for example, Patent Document 1).

[0005] However, this method requires the application and removal of a covering member, and also requires two cutting blades with different cutting thicknesses, which increases the number of management steps and manufacturing costs. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-036660 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above problems, and aims to reduce the amount of burrs remaining at the intended dividing line of a workpiece when the workpiece is cut with a single cutting blade without using a covering member. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a cutting method comprising: a first cutting step in which a workpiece held on a holding table is cut with a cutting blade along a predetermined dividing line set on the workpiece; and a second cutting step in which the thickness of the cutting blade is set to a second thickness greater than the first thickness of the cutting blade in the first cutting step, and the workpiece is cut along the predetermined dividing line with the cutting blade having the second thickness, thereby removing at least burrs generated on the predetermined dividing line in the first cutting step, wherein the difference between the first thickness and the second thickness is obtained by applying an external stimulus to the cutting blade in the first cutting step or the second cutting step.

[0009] According to another aspect of the present invention, there is provided a cutting device comprising: a holding table for holding a workpiece; a cutting unit having a spindle for cutting the workpiece held by the holding table with a cutting blade attached to the spindle; an external stimulus applying section for applying an external stimulus to the cutting blade to change the thickness of the cutting blade; and a controller for controlling at least the operation of the cutting unit and the external stimulus applying section, wherein the controller is configured to change the thickness of the cutting blade to a second thickness greater than the first thickness in a first cutting step in which the workpiece held by the holding table is cut with the cutting blade along a predetermined dividing line set on the workpiece, and to change the thickness of the cutting blade to a second thickness greater than the first thickness in a second cutting step in which burrs generated on the predetermined dividing line in the first cutting step are at least removed, and the difference between the first thickness and the second thickness is obtained by applying an external stimulus to the cutting blade in the first cutting step or the second cutting step.

[0010] Preferably, the external stimulus imparting unit is a rotary drive unit provided in the cutting unit and having a motor for rotating the spindle, and the controller reduces the rotational speed of the spindle in the second cutting step compared to the first cutting step, thereby setting the thickness of the cutting blade to the second thickness greater than the first thickness.

[0011] Preferably, the external stimulus applying unit has a temperature adjustment unit that performs at least one of heating and cooling on the cutting blade, and the controller causes the temperature adjustment unit to increase the temperature of the cutting blade in the second cutting step compared to the first cutting step, thereby making the thickness of the cutting blade the second thickness that is greater than the first thickness.

[0012] Preferably, the cutting unit has a cutting blade holding portion for attaching the cutting blade to the spindle while clamping the cutting blade in the thickness direction of the cutting blade, and the temperature adjustment unit is provided in the cutting blade holding portion, and the temperature adjustment unit performs at least one of heating and cooling of the cutting blade by heat conduction through the cutting blade holding portion.

[0013] Preferably, the temperature adjustment unit includes a heater fixed to the cutting unit and disposed adjacent to the cutting blade for supplying heat to the cutting blade.

[0014] Preferably, the cutting unit has a cutting fluid supply nozzle that supplies cutting fluid to the cutting blade and the workpiece, and the temperature adjustment unit is provided in a flow path that supplies the cutting fluid to the cutting fluid supply nozzle, and performs at least one of heating and cooling of the cutting fluid before it is supplied to the cutting blade and the workpiece.

[0015] Preferably, the cutting unit has a cutting blade holding portion for attaching the cutting blade to the spindle while clamping the cutting blade in the thickness direction of the cutting blade, and the external stimulus applying portion includes a piezoelectric element provided in the cutting blade holding portion and a power supply unit provided in the cutting unit and having a coil for applying voltage to the piezoelectric element, and the controller operates the piezoelectric element to set the thickness of the cutting blade to the second thickness greater than the first thickness in the second cutting process.

[0016] Preferably, the external stimulus applying unit is an ultrasonic vibration generating unit including the piezoelectric element and the power supply unit, and in the second cutting process, the controller periodically causes the ultrasonic vibration generating unit to generate ultrasonic vibrations, thereby causing the thickness of the cutting blade to be the second thickness, which is greater than the first thickness. [Effects of the Invention]

[0017] In a cutting method according to one embodiment of the present invention, in a second cutting step following a first cutting step in which a workpiece is cut along a planned dividing line with a cutting blade, the thickness of the cutting blade is set to a second thickness that is larger than the first thickness of the cutting blade in the first cutting step, and the workpiece is cut along the planned dividing line with the cutting blade having the second thickness.

[0018] In another aspect of the cutting device of the present invention, when the thickness of the cutting blade is a first thickness in a first cutting step in which the workpiece is cut along the intended dividing line with the cutting blade, the thickness of the cutting blade is set to a second thickness greater than the first thickness in a second cutting step in which at least burrs generated on the intended dividing line in the first cutting step are removed.

[0019] In either embodiment, the difference between the first thickness and the second thickness is obtained by applying an external stimulus to the cutting blade in the first cutting step or the second cutting step, without replacing the cutting blade. In this way, in the second cutting step, at least the burrs generated on the dividing line in the first cutting step are removed using a single cutting blade without using a covering member, so that the amount of burrs remaining on the dividing line of the workpiece can be reduced. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. 10 is a partial cross-sectional side view showing an outline of a cutting process. [Figure 4] FIG. 2 is a perspective view of a blade position detection unit. [Figure 5] FIG. 1 is a flow chart showing a cutting method. [Figure 6] FIG. 6(A) is a side view of the cutting blade in the first cutting step, and FIG. 6(B) is a cross-sectional view showing the first cutting groove formed in the first cutting step. [Figure 7] FIG. 7(A) is a side view of the cutting blade in the second cutting step, and FIG. 7(B) is a cross-sectional view showing the second cutting groove formed in the second cutting step. [Figure 8] FIG. 10 is a partial cross-sectional side view of a cutting unit according to a second embodiment. [Figure 9] FIG. 9(A) is a side view of the cutting blade in the first cutting step of the second embodiment, and FIG. 9(B) is a cross-sectional view showing the first cutting groove formed in the first cutting step. [Figure 10] FIG. 10(A) is a side view of the cutting blade in the second cutting step of the second embodiment, and FIG. 10(B) is a cross-sectional view showing the second cutting groove formed in the second cutting step of the second embodiment. [Figure 11] FIG. 11(A) is a partial cross-sectional side view of a cutting unit in a first modified example, and FIG. 11(B) is a partial cross-sectional side view of a cutting unit in a second modified example. [Figure 12] FIG. 10 is a side view of a cutting unit according to a third embodiment. [Figure 13] FIG. 10 is a partial cross-sectional side view of a cutting unit according to a fourth embodiment. [Figure 14] FIG. 14(A) is a side view of the cutting blade in the first cutting step of the fourth embodiment, and FIG. 14(B) is a side view of the cutting blade in the second cutting step of the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] (First embodiment) An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of a cutting device 2. In Fig. 1, some of the components are shown as functional blocks. The X-axis, Y-axis, and Z-axis shown in Fig. 1 are perpendicular to one another.

[0022] The X-axis is parallel to a machining feed direction, which will be described later, and the Y-axis is parallel to an indexing feed direction, which will be described later. The Z-axis direction is parallel to the vertical direction and the height direction of the cutting device 2. In this specification, the direction parallel to the X-axis may be referred to as the X-axis direction, the direction parallel to the Y-axis may be referred to as the Y-axis direction, and the direction parallel to the Z-axis may be referred to as the Z-axis direction.

[0023] The cutting device 2 includes a base 4 that supports each of the components. A ball screw type X-axis direction movement unit (processing feed unit) 6 is provided on an upper surface 4a of the base 4. The X-axis direction movement unit 6 has a pair of guide rails 8 that are fixed to the upper surface 4a and arranged parallel to the X-axis.

[0024] An X-axis direction moving plate 10 is slidably fixed on the pair of guide rails 8. A nut portion (not shown) is fixed to the underside of the X-axis direction moving plate 10. A screw shaft 12, which is arranged parallel to the X-axis, is rotatably connected to the nut portion via a plurality of balls (not shown).

[0025] A drive source 14 such as a servo motor or a stepping motor is fixed to one end of the screw shaft 12. When the drive source 14 is operated, the X-axis direction moving plate 10 moves along the X-axis. An optical or magnetic first sensor (not shown) is provided on the underside of the X-axis direction moving plate 10.

[0026] In addition, an optical or magnetic first linear scale (not shown) is provided near one of the guide rails 8. The first sensor and the first linear scale constitute a first linear encoder for detecting the position of the X-axis direction moving plate 10 in the X-axis direction.

[0027] A cylindrical support part 16 is fixed on the X-axis direction moving plate 10. A drive source (not shown), such as a motor, is provided inside the support part 16 to rotate a chuck table (holding table) 18 (described later) around a rotation axis arranged parallel to the Z axis.

[0028] A disk-shaped chuck table 18 (see FIG. 3) is detachably attached to the upper part of the support part 16. The position of the chuck table 18 is indicated by an arrow in FIG. 1. The chuck table 18 has a disk-shaped frame body made of metal.

[0029] A recess with a smaller diameter than the frame is formed on the top surface of the frame, and a porous plate made of porous ceramics is fixed in this recess with adhesive, etc. The top surfaces of the frame and the porous plate are substantially flush with each other, forming a flat holding surface 18a (see FIG. 3) that is substantially parallel to the XY plane.

[0030] A suction source (not shown), such as a vacuum pump, is connected to the chuck table 18 via a predetermined flow path. The negative pressure generated by the suction source is transmitted to the upper surface of the porous plate. A plurality of clamp units 20 (four in the example shown in FIG. 1) are provided on the outer periphery of the chuck table 18.

[0031] Each clamp unit 20 has a pair of rods whose positions are fixed relative to the chuck table 18. A receiving base is fixed to the tip end of the pair of rods. The receiving base is provided with claws that are rotated relative to the receiving base by an air actuator.

[0032] When each clamp unit 20 holds the annular frame 25 of the workpiece unit 27 (described later) between the pedestal and the claws, the claws are rotated to bring their tips closer to the pedestal (closing operation). Conversely, when the claws are rotated to move their tips away from the pedestal, the top surface of the pedestal is opened (opening operation).

[0033] 2 and 3, the workpiece 11 and other components held by suction on the chuck table 18 will be described. Fig. 2 is a plan view of the workpiece 11. The workpiece 11 in this embodiment is a so-called strip substrate, and has a semiconductor package substrate 13 including a rectangular metal frame (lead frame).

[0034] The semiconductor package substrate 13 is divided into three device regions 15a, 15b, and 15c in the longitudinal direction of the semiconductor package substrate 13 by a peripheral excess region 13a of the metal frame and a non-device region 13b.

[0035] A plurality of division lines 17 are set in advance in a grid pattern in each of the device regions 15a, 15b, and 15c. Each of the division lines 17 has a predetermined width. A semiconductor device chip (not shown) is disposed in each of the rectangular regions 17a defined by the division lines 17.

[0036] Each semiconductor device chip is not exposed on the surface 11a, but is covered with a molded resin layer 19 (see FIG. 3) provided on the back surface of the semiconductor package substrate 13 (i.e., the surface opposite to the surface 11a).

[0037] A plurality of metal terminals 21 are provided on each of the planned dividing lines 17 in a manner that exposes them on the surface 11a. The semiconductor device chip is electrically connected to the plurality of metal terminals 21 located in the vicinity thereof by bonding wires or the like (not shown).

[0038] The semiconductor device chip is not electrically connected to the plurality of metal terminals 21 located in the peripheral excess region 13 a and the non-device region 13 b. These metal terminals 21 are used, for example, as markers (i.e., alignment marks) during cutting.

[0039] The workpiece 11 is not limited to a strip substrate. The workpiece 11 may be a semiconductor wafer provided with a TEG (Test Element Group) having a metal wiring layer or the like on the planned dividing lines 17, or may be a semiconductor wafer having a metal film that functions as a heat sink or the like.

[0040] 1, a circular dicing tape 23 is adhesively fixed to the back surface 11b (i.e., the exposed surface of the mold resin) of the workpiece 11 so that the front surface 11a of the workpiece 11 is exposed. One surface of a metal annular frame 25 is adhesively fixed to the outer periphery of the dicing tape 23.

[0041] The workpiece 11 is held by suction on the chuck table 18 in the form of a workpiece unit 27 in which the workpiece 11 is supported via a dicing tape 23 in the center of the opening of the annular frame 25 .

[0042] A gate-shaped support structure 4b is provided on the upper surface 4a of the base 4 so as to straddle the X-axis direction moving unit 6. A Y-axis direction moving unit (indexing feed unit) 22 is provided on one surface of the support structure 4b.

[0043] The Y-axis direction moving unit 22 has a pair of guide rails 24 arranged parallel to the Y-axis direction. A Y-axis direction moving plate 26 is slidably attached to the pair of guide rails 24.

[0044] A nut portion (not shown) is provided on the back surface of the Y-axis direction moving plate 26. A screw shaft 28, which is arranged parallel to the Y-axis direction, is rotatably connected to this nut portion via a plurality of balls (not shown).

[0045] A drive source 30 such as a servo motor or a stepping motor is fixed to one end of the screw shaft 28. When the drive source 30 is operated, the Y-axis direction moving plate 26 moves along the Y-axis. A second optical or magnetic sensor (not shown) is provided on the back surface of the Y-axis direction moving plate 26.

[0046] In addition, a second optical or magnetic linear scale (not shown) is provided near one of the guide rails 24. The second sensor and the second linear scale constitute a second linear encoder for detecting the position of the Y-axis direction moving plate 26 in the Y-axis direction.

[0047] A Z-axis direction moving unit (cutting feed unit) 32 is provided on the surface of the Y-axis direction moving plate 26. The Z-axis direction moving unit 32 has a pair of guide rails 34 arranged parallel to the Z-axis direction.

[0048] A Z-axis direction moving plate 36 is slidably attached to the pair of guide rails 34. A nut portion (not shown) is provided on the back surface of the Z-axis direction moving plate 36. A screw shaft 38 arranged parallel to the Z-axis direction is rotatably connected to this nut portion via a plurality of balls (not shown).

[0049] A drive source 40 such as a servo motor or a stepping motor is fixed to one end of the screw shaft 38. When the drive source 40 is operated, the Z-axis direction moving plate 36 moves along the Z-axis. A third optical or magnetic sensor (not shown) is provided on the back surface of the Z-axis direction moving plate 36.

[0050] In addition, an optical or magnetic third linear scale (not shown) is provided near one of the guide rails 34. The third sensor and the third linear scale constitute a third linear encoder for detecting the position of the Z-axis direction moving plate 36 in the Z-axis direction.

[0051] A quadrangular prism-shaped spindle housing 44 that constitutes the cutting unit 42 is fixed to the lower end of the Z-axis direction moving plate 36. The longitudinal direction of the spindle housing 44 is disposed along the Y-axis.

[0052] A cylindrical spindle 46 (see FIG. 3) is rotatably housed in the spindle housing 44 by a so-called air bearing. The cutting unit 42 is provided with a rotation drive section (external stimulus applying section) 50 including a motor 48 that rotates the spindle 46 at high speed.

[0053] As shown in FIG. 3, a stator 52 that constitutes a motor 48 is disposed around a portion of the spindle 46 in the spindle housing 44, and the spindle 46 functions as the rotor and output shaft of the motor 48.

[0054] The spindle 46 rotates due to the power supplied to the stator 52. In this embodiment, a hubless (i.e., washer) annular cutting blade (i.e., cutting edge) 54 is attached to the tip of the spindle 46.

[0055] A disk-shaped receiving flange 56 is fixed to the tip of the spindle 46 by a bolt 46b via a washer 46a (see FIG. 8). The receiving flange 56 has a cylindrical boss 56a (see FIG. 8) located radially outward of the washer 46a and the bolt 46b.

[0056] This boss portion 56a is inserted into a through-hole 58a (see FIG. 8) formed in the radial center of the disk-shaped pressing flange portion 58. When the cutting blade 54 is sandwiched and fixed between the receiving flange portion 56 and the pressing flange portion 58, the flange surface of the receiving flange portion 56 and the flange surface of the pressing flange portion 58 come into contact with the cutting blade 54.

[0057] A male thread 56b is provided at the tip of the boss portion 56a of the receiving flange portion 56. A female thread 60a of a press nut 60 is fastened to this male thread 56b. By tightening the press nut 60, the flange surface of the press flange portion 58 is pressed into the flange surface of the receiving flange portion 56.

[0058] The washer 46a, bolt 46b, receiving flange portion 56, pressing flange portion 58, pressing nut 60, etc. are formed from metal such as aluminum alloy or stainless steel, and form a cutting blade holding portion 62 that attaches the cutting blade 54 to the tip of the spindle 46 while clamping the cutting blade 54 in the thickness direction of the cutting blade 54.

[0059] In this embodiment, a hubless cutting blade 54 is attached to the tip of the spindle 46, but instead, a hub-type cutting blade 54 having a disk-shaped metal base and an annular cutting blade fixed to the base so as to protrude from the outer edge of the base in the radial direction of the base may be attached to the tip of the spindle 46.

[0060] In this case, the retaining flange portion 58 is omitted, and by fastening the retaining nut 60 to the boss portion 56a of the receiving flange portion 56, the cutting blade 54 is attached to the tip of the spindle 46 with the base clamped between the receiving flange portion 56 and the retaining nut 60.

[0061] 3 is a partially cross-sectional side view showing an overview of the cutting process for cutting workpiece 11 with cutting unit 42. When cutting workpiece 11, first, workpiece 11 is suction-held by holding surface 18a via dicing tape 23, and annular frame 25 is held by clamp unit 20.

[0062] Next, the lower end of the cutting blade 54, which is rotating at high speed, is positioned in the Z-axis direction between the surface 11a and the holding surface 18a, and the cutting blade 54 is positioned on an extension of the intended dividing line 17 in the XY plane.

[0063] Then, the chuck table 18 is moved along the X-axis (i.e., the chuck table 18 is fed for processing) while a cutting fluid 64a such as pure water is supplied to the cutting blade 54. For example, by moving the chuck table 18 along the X-axis, the workpiece 11 is cut (for example, fully cut) along the intended dividing line 17.

[0064] The cutting fluid 64a is supplied from various nozzles provided on the blade cover 64. The blade cover 64 is attached to the tip of the spindle housing 44, and covers the upper side and both sides in the X-axis direction of the cutting blade 54 (see FIGS. 1 and 12).

[0065] Now, the blade cover 64 will be described with reference to Figure 12. The blade cover 64 has an upper cover portion 66. A first cover portion 68 is provided at one end of the upper cover portion 66 in the X-axis direction and extends downward.

[0066] A pair of arms 70 are provided at the lower end of the first cover part 68 so as to sandwich the cutting blade 54 in the Y-axis direction. Note that Fig. 12 shows only one of the arms 70, which is located on the front side of the page.

[0067] A plurality of cooler nozzles 70a are provided on the inner surfaces of the pair of arm portions 70 to spray cutting fluid 64a onto the contact area (i.e., the processing point) between the cutting blade 54 and the workpiece 11. A second cover portion 72 is provided at the other end of the upper cover portion 66 in the X-axis direction, extending downward.

[0068] One or more shower nozzles 72a are provided near the tips of the pair of arm portions 70 of the second cover portion 72 to spray cutting fluid 64a onto the outer periphery of the cutting blade 54. In Fig. 12, only one shower nozzle 72a located on the front side of the page is shown.

[0069] In the second cover part 72, a spray nozzle 72b is provided outside the shower nozzle 72a (i.e., on the opposite side of the pair of arms 70 from the shower nozzle 72a in the X-axis direction), which sprays cutting fluid 64a approximately directly downward toward the workpiece 11.

[0070] The plurality of cooler nozzles 70 a, one or more shower nozzles 72 a, and spray nozzle 72 b constitute a cutting fluid supply nozzle 74 that supplies cutting fluid 64 a to the cutting blade 54 and the workpiece 11.

[0071] The cutting fluid 64a is supplied to the blade cover 64 from a cutting fluid supply source 76. The cutting fluid supply source 76 includes a tank that stores pure water or the like, a pump that supplies the pure water from the tank, etc. The cutting fluid supply source 76 is, for example, a cutting water supply device that is provided separately from the cutting device 2, or a cutting water supply device installed in a building.

[0072] 1 again, a description will be given of other components of the cutting device 2. A microscope camera unit 80 that captures an image of the workpiece 11 held by the holding surface 18a is fixed to the side surface of the spindle housing 44 in the X-axis direction.

[0073] The microscope camera unit 80 includes a light source such as an LED (Light Emitting Diode), a predetermined optical system including a lens, and a solid-state imaging element such as a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor or a CCD (Charge-Coupled Device) image sensor.

[0074] A blade position detection unit (setup unit) 82 is provided below the spindle housing 44 and fixed to the base 4. The blade position detection unit 82 is used to detect the height position of the lower end of the cutting blade 54 (i.e., the position in the Z-axis direction).

[0075] Here, the blade position detection unit 82 will be described with reference to Fig. 4. Fig. 4 is a perspective view of the blade position detection unit 82 used in the blade position detection process (setup process) for detecting the height position of the lower end of the cutting blade 54. The blade position detection unit 82 has a detector 84 that has an optical sensor.

[0076] The detector 84 includes a rectangular parallelepiped support portion 84a and a detection portion 84b having a pair of protrusions. The lower end of the cutting blade 54 is inserted between the pair of protrusions. A light-emitting portion 86 including an LED or the like that emits light L in a predetermined wavelength band, such as visible light, is provided on the inner surface of one of the protrusions, and a light-receiving portion 88 including a photoelectric conversion element or the like that receives the light L from the light-emitting portion 86 is provided on the inner surface of the other protrusion.

[0077] The support portion 84a is provided with two first nozzles 90 for spraying dry air onto the light-emitting portion 86 and the light-receiving portion 88, and two second nozzles 92 for spraying a liquid such as pure water onto the light-emitting portion 86 and the light-receiving portion 88.

[0078] A rectangular parallelepiped cover 96 is attached to the base end of the detection unit 84b via a connector 94 such as a hinge. The interior of the cover 96 is hollow, and by rotating the cover 96 around the connector 94, the detection unit 84b, the first nozzle 90, the second nozzle 92, etc. can be housed within the cover 96. Note that FIG. 4 shows an open state in which the detection unit 84b, etc. are exposed from the cover 96.

[0079] When the blade position detection unit 82 detects the height position of the lower end of the cutting blade 54, first, the detection part 84b is exposed. Then, the Z-axis direction moving unit 32 gradually lowers the cutting unit 42, and the cutting blade 54, which is rotating at high speed, is inserted between the light-emitting part 86 and the light-receiving part 88.

[0080] Then, the position of the cutting unit 42 in the Z-axis direction when the amount of light received by the light receiving section 88 becomes equal to or less than a predetermined threshold is read by the linear encoder of the Z-axis movement unit 32. A change in the diameter of the cutting blade 54 can be detected from the change in the position of the cutting unit 42 in the Z-axis direction when the amount of light received by the light receiving section 88 becomes equal to or less than a predetermined threshold.

[0081] For example, the change in diameter of the cutting blade 54 can be determined by the difference between a first position in the Z-axis direction of the cutting unit 42 when an unused cutting blade 54 is inserted between the light-emitting unit 86 and the light-receiving unit 88 and the amount of light received by the light-receiving unit 88 is below a threshold, and a second position in the Z-axis direction of the cutting unit 42 when a cutting blade 54 whose diameter has changed due to deformation, wear, etc. is inserted between the light-emitting unit 86 and the light-receiving unit 88 and the amount of light received by the light-receiving unit 88 is below a threshold.

[0082] The blade position detection unit 82 is used to detect the position of the lower end of the cutting blade 54 before the first cutting step S10 and the second cutting step S20, which will be described later. As will be described in detail later, the diameter of the cutting blade 54 can change depending on the rotation speed of the spindle 46, the temperature of the cutting blade 54, the vibration frequency transmitted to the cutting blade 54, etc.

[0083] Therefore, before the first cutting step S10 and the second cutting step S20, the position of the lower end of the cutting blade 54 may be detected by the blade position detection unit 82. This allows the cutting depth of the cutting blade 54 to be controlled with higher accuracy than when position detection is not performed by the blade position detection unit 82.

[0084] 1 again, the operations of the X-axis direction moving unit 6, the drive source in the support part 16, the clamp unit 20, the Y-axis direction moving unit 22, the Z-axis direction moving unit 32, the cutting unit 42 including the rotation drive part 50, the blade position detection unit 82, the linear encoders, etc. are controlled by a controller 100.

[0085] The controller 100 is configured by a computer including, for example, a processor 100a represented by a CPU (Central Processing Unit) and a memory 100b. The memory 100b includes a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a flash memory, a hard disk drive, or a solid state drive.

[0086] The auxiliary storage device stores software including a predetermined program. The functions of the controller 100 are realized by operating the processor 100a and the like in accordance with this software.

[0087] Next, a cutting method according to the first embodiment will be described with reference to Fig. 5 to Fig. 7(B). Fig. 5 is a flow chart showing the cutting method. In the first embodiment, the workpiece 11 is cut in the order of a first cutting step S10 and a second cutting step S20.

[0088] 6(A) is a side view of the cutting blade 54 in the first cutting step S10. In the first cutting step S10 of the first embodiment, the controller 100 controls the rotation drive unit 50 to relatively increase the rotation speed of the spindle 46. The cutting blade 54, which rotates at a relatively high rotation speed, elastically changes shape in response to an external stimulus such as centrifugal force, such that the outer periphery 54b tapers.

[0089] That is, in the first cutting step S10, the thickness 54b1 of the outer peripheral portion 54b of the cutting blade 54 (i.e., the first thickness 54d1) is smaller by, for example, about 1 μm compared to the thickness 54c1 of the inner peripheral portion 54c of the cutting blade 54 located on the outer periphery of the receiving flange portion 56 and the pressing flange portion 58. At this time, the diameter of the cutting blade 54 becomes slightly larger.

[0090] In this way, the controller 100 controls the rotation drive unit 50, thereby changing the thickness of the cutting blade 54 in response to an external stimulus, namely, the high-speed rotation of the spindle 46. In the first cutting step S10, after the cutting blade 54 has been deformed into a tapered shape in this manner, the lower end of the cutting blade 54 is positioned between the back surface 11b and the holding surface 18a.

[0091] Then, after cutting the workpiece 11 with the cutting blade 54 along each planned dividing line 17 along the first direction, the chuck table 18 is rotated 90 degrees, and the workpiece 11 is cut with the cutting blade 54 along each planned dividing line 17 along a second direction perpendicular to the first direction.

[0092] This forms notch grooves in the dicing tape 23 that are large enough not to cut the dicing tape 23, and cuts the workpiece 11, dividing the workpiece 11 into multiple semiconductor packages (not shown). Figure 6(B) is a cross-sectional view showing the first cut grooves 11c1 formed in the first cutting step S10. An example of processing conditions for the first cutting step S10 is shown below.

[0093] Outer blade thickness: 300 μm Spindle rotation speed: 30,000 rpm Processing feed rate: 50mm / s Cutting water supply rate: 2.0L / min

[0094] In the first cutting step S10, burrs 21a (see FIG. 6(B)) are generated on the planned dividing line 17 near the surface 11a as a result of cutting the metal terminals 21 provided on the planned dividing line 17. Therefore, in the subsequent second cutting step S20, the workpiece 11 is cut again to remove at least the burrs 21a.

[0095] 7(A) is a side view of the cutting blade 54 in the second cutting step S20. In the second cutting step S20, the controller 100 controls the rotation drive unit 50 to reduce the rotation speed of the spindle 46 below that in the first cutting step S10.

[0096] As a result, deformation of the cutting blade 54 due to centrifugal force, etc. does not occur, so the thickness 54c1 of the inner peripheral portion 54c of the cutting blade 54 located on the outer periphery of the receiving flange portion 56 and the pressing flange portion 58 and the thickness 54b1 of the outer peripheral portion 54b of the cutting blade 54 are approximately the same thickness (second thickness 54d2).

[0097] In other words, in the second cutting step S20, by not applying an external stimulus to the cutting blade 54 that is strong enough to cause deformation, the thickness 54b1 of the outer peripheral portion 54b of the cutting blade 54 is made a second thickness 54d2 that is larger than the thickness 54b1 (i.e., the first thickness 54d1) of the outer peripheral portion 54b of the cutting blade 54 in the first cutting step S10.

[0098] In this way, the difference between the first thickness 54d1 and the second thickness 54d2 at the outer peripheral portion 54b is obtained by applying an external stimulus to the cutting blade 54 at a high rotation speed in the first cutting step S10, and not applying an external stimulus at a low rotation speed in the second cutting step S20.

[0099] The diameter of the cutting blade 54 in the second cutting step S20 is slightly smaller than that in the first cutting step S10. In the second cutting step S20, the thickness 54b1 of the outer circumferential portion 54b is set to the second thickness 54d2, and then the lower end of the cutting blade 54 is positioned between the back surface 11b and the holding surface 18a.

[0100] Then, the workpiece 11 is cut along each of the planned dividing lines 17 along the first direction by the cutting blade 54. Thereafter, the chuck table 18 is rotated 90 degrees, and then the workpiece 11 is cut along each of the planned dividing lines 17 along the second direction by the cutting blade 54.

[0101] This removes burrs 21a near the surface 11a and cuts the inner surface of the first cut groove 11c1. Figure 7(B) is a cross-sectional view showing the second cut groove 11c2 formed in the second cutting step S20. In Figure 7(B), the first cut groove 11c1 is indicated by a dashed line.

[0102] An example of processing conditions in the second cutting step S20 is shown below: In the second cutting step S20, the removal volume is smaller than in the first cutting step S10, so the processing feed rate can be increased by more than two times.

[0103] Outer blade thickness: 301 μm Spindle rotation speed: 10,000 rpm Processing feed rate: 100mm / s Cutting water supply rate: 2.0L / min

[0104] In this embodiment, at least the burrs 21a generated on the planned dividing line 17 in the first cutting step S10 are removed using a single cutting blade 54 without using a covering member, thereby reducing the amount of burrs 21a that ultimately remain on the planned dividing line 17 of the workpiece 11.

[0105] Second Embodiment Next, a second embodiment will be described with reference to Fig. 8 to Fig. 11(B). Fig. 8 is a partially cross-sectional side view of a cutting unit 42 according to the second embodiment. In the second embodiment, an annular groove 56c is formed on the outer periphery of the receiving flange 56.

[0106] An electric heating wire (temperature control unit, external stimulus applying unit) 102 is provided in the groove portion 56c so as to be wound around the outer periphery of the receiving flange portion 56. The electric heating wire 102 is a nichrome wire or the like formed from an alloy material mainly containing nickel (Ni) and chromium (Cr).

[0107] The controller 100 controls whether or not the heating wire 102 generates heat by controlling the supply of power to the heating wire 102. When power is supplied to the heating wire 102 and the heating wire 102 generates heat, the cutting blade 54 is heated by thermal conduction via the receiving flange portion 56 (i.e., the cutting blade 54 is heated). When the power is cut off, the heating wire 102 does not generate heat, and the cutting blade 54 quickly cools down over time.

[0108] 9(A) is a side view of the cutting blade 54 in the first cutting step S10 of the second embodiment. In the first cutting step S10, the heating wire 102 is not heated, so that the temperature of the cutting blade 54 is set to approximately 20°C. At this time, the thickness 54b1 of the outer circumferential portion 54b of the cutting blade 54 and the thickness 54c1 of the inner circumferential portion 54c are substantially the same as the first thickness 54d1.

[0109] Next, after the lower end of the cutting blade 54 is positioned between the back surface 11b and the holding surface 18a, the workpiece 11 is cut along each of the planned dividing lines 17 along the first direction with the cutting blade 54. Thereafter, the chuck table 18 is rotated 90 degrees.

[0110] Next, the workpiece 11 is cut along each of the planned division lines 17 along the second direction by the cutting blade 54. Fig. 9(B) is a cross-sectional view showing the first cutting groove 11c1 formed in the first cutting step S10. An example of the processing conditions in the first cutting step S10 is shown below.

[0111] Outer blade thickness: 300 μm Spindle rotation speed: 20,000 rpm Processing feed rate: 50mm / s Cutting water supply rate: 2.0L / min Cutting blade temperature: 20℃

[0112] In the first cutting step S10, as described above, burrs 21a are generated on the dividing line 17 near the surface 11a. In the second cutting step S20, the workpiece 11 is cut again to remove at least the burrs 21a. Fig. 10(A) is a side view of the cutting blade 54 in the second cutting step S20 of the second embodiment.

[0113] In the second cutting step S20 of the second embodiment, the controller 100 causes the heating wire 102 to generate heat, thereby increasing the temperature of the cutting blade 54 to approximately 70° C. and causing thermal expansion.

[0114] Since the cutting blade 54 is sandwiched between the receiving flange portion 56 and the holding flange portion 58, the cutting blade 54 is elastically deformed so that the outer peripheral portion 54b becomes relatively thicker than the inner peripheral portion 54c.

[0115] That is, in the second cutting step S20, an external stimulus strong enough to cause deformation is applied to the cutting blade 54, thereby changing the thickness 54b1 of the outer periphery 54b of the cutting blade 54 to a second thickness 54d2 that is larger than the thickness 54b1 (i.e., the first thickness 54d1) of the outer periphery 54b of the cutting blade 54 in the first cutting step S10. Note that due to thermal expansion, the diameter of the cutting blade 54 may become slightly larger than in the first cutting step S10.

[0116] In the second cutting step S20, the thickness 54b1 of the outer circumferential portion 54b is increased to a second thickness 54d2, and then the lower end of the cutting blade 54 is positioned between the back surface 11b and the holding surface 18a. Then, the workpiece 11 is cut with the cutting blade 54 along each of the planned dividing lines 17 in the first direction.

[0117] Thereafter, the chuck table 18 is rotated 90 degrees. Next, the workpiece 11 is cut with the cutting blade 54 along each of the planned dividing lines 17 in the second direction. As a result, the burrs 21a near the surface 11a are removed and the inner surface of the first cutting groove 11c1 is cut.

[0118] 10(B) is a cross-sectional view showing the second cutting groove 11c2 formed in the second cutting step S20 of the second embodiment. In FIG. 10(B), the first cutting groove 11c1 is indicated by a dashed line. An example of the processing conditions in the second cutting step S20 is shown below.

[0119] Outer blade thickness: 301 μm Spindle rotation speed: 20,000 rpm Processing feed rate: 100mm / s Cutting water supply rate: 2.0L / min Cutting blade temperature: 70℃

[0120] In the second embodiment, too, a single cutting blade 54 is used without using a covering member to remove at least the burrs 21a that occur on the planned dividing line 17 in the first cutting step S10, thereby reducing the amount of burrs 21a that ultimately remain on the planned dividing line 17 of the workpiece 11.

[0121] 11(A) is a partial cross-sectional side view of the cutting unit 42 in a first modified example of the second embodiment. In the first modified example, instead of the heating wire 102, a heater (temperature adjustment unit, external stimulus applying unit) 104 is fixed to the Z-axis moving plate 36.

[0122] That is, the heater 104 is fixed to the cutting unit 42. The heater 104 is adjacent to the outer periphery 54b of the cutting blade 54 in the Y-axis direction, but is disposed apart from the cutting blade 54, the receiving flange 56, the holding flange 58, etc. The operation of the heater 104 is also controlled by the controller 100.

[0123] The heater 104 is a dryer that supplies heat to the cutting blade 54 by sending heat generated by an electric heating wire to the cutting blade 54 using air generated by a fan or the like, or an infrared heater that supplies heat to the cutting blade 54 by emitting infrared rays.

[0124] In the first cutting step S10 of the first modified example, by not supplying heat to the cutting blade 54, the temperature of the cutting blade 54 is set to approximately 20°C, and the thickness 54b1 of the outer periphery 54b of the cutting blade 54 is set to a relatively small first thickness 54d1 (see Figure 9(A)).

[0125] In contrast, in the second cutting process S20 of the first modified example, heat is supplied to the cutting blade 54 to raise the temperature of the cutting blade 54 to approximately 70°C, and the thickness 54b1 of the outer periphery 54b of the cutting blade 54 is set to a relatively large second thickness 54d2 (see Figure 10(A)).

[0126] 11(B) is a partial cross-sectional side view of the cutting unit 42 in a second modified example of the second embodiment. In the second modified example, instead of the heating wire 102, a circular Peltier element (temperature adjustment unit, external stimulus applying unit) 106 is provided in the groove 56c of the receiving flange 56.

[0127] The operation of the Peltier element 106 is also controlled by the controller 100. The Peltier element 106 has an annular first surface 106a that is relatively close to the cutting blade 54, and an annular second surface 106b that is located on the opposite side of the first surface 106a in the thickness direction of the Peltier element 106 and relatively far from the cutting blade 54.

[0128] The Peltier element 106 is provided with first and second lead wires (not shown). For example, if the first lead wire is connected to the positive terminal of a DC power supply and the second lead wire is connected to the negative terminal of the DC power supply, the first surface 106a generates heat and the second surface 106b absorbs heat. In this case, the cutting blade 54 is mainly heated by the Peltier element 106.

[0129] On the other hand, if the first lead wire is connected to the negative terminal of the DC power supply and the second lead wire is connected to the positive terminal of the DC power supply, the first surface 106a absorbs heat and the second surface 106b generates heat. In this case, the cutting blade 54 is mainly cooled by the Peltier element 106.

[0130] In this way, while the heating wire 102 and the heater 104 only heat the cutting blade 54, the Peltier element 106 can both heat and cool the cutting blade 54. In the second modified example, for example, the cutting blade 54 is neither heated nor cooled in the first cutting step S10, and is heated in the second cutting step S20.

[0131] As an alternative approach, the cutting blade 54 is cooled in the first cutting step S10, and is neither heated nor cooled in the second cutting step S20. As a further alternative approach, the cutting blade 54 is cooled in the first cutting step S10, and is heated in the second cutting step S20.

[0132] In any case, in the first cutting step S10 of the second modified example, the thickness 54b1 of the outer peripheral portion 54b of the cutting blade 54 can be set to a relatively small first thickness 54d1 (see Figure 9(A)), and in the second cutting step S20 of the first modified example, the thickness 54b1 of the outer peripheral portion 54b of the cutting blade 54 can be set to a relatively large second thickness 54d2 (see Figure 10(A)).

[0133] (Third Embodiment) Next, a third embodiment will be described with reference to Fig. 12. Fig. 12 is a side view of a cutting unit 42 in the third embodiment. The cutting device 2 of the third embodiment has a heating / cooling mechanism (temperature adjustment unit, external stimulus applying unit) 110 provided in a flow path 108 that supplies cutting fluid 64a from a cutting fluid supply source 76 to the cooler nozzle 70a and the shower nozzle 72a.

[0134] The heating and cooling mechanism 110 includes a temperature sensor that measures the temperature of the cutting fluid 64a in the flow path 108, a heater for heating the cutting fluid 64a, and a cooling pipe through which a refrigerant flows to cool the cutting fluid 64a (none of which are shown).

[0135] Therefore, the heating and cooling mechanism 110 can both heat and cool the cutting fluid 64a before it is supplied to the cutting blade 54 and the workpiece 11. In the third embodiment, the thickness 54b1 of the outer periphery 54b of the cutting blade 54 is adjusted by adjusting the temperature of the cutting fluid 64a. An example of processing conditions for the first cutting step S10 in the third embodiment is shown below.

[0136] Outer blade thickness: 300 μm Spindle rotation speed: 20,000 rpm Processing feed rate: 50mm / s Cutting water supply rate: 2.0L / min Cutting blade temperature: 20℃

[0137] An example of the processing conditions for the second cutting step S20 in the third embodiment is shown below.

[0138] Outer blade thickness: 301 μm Spindle rotation speed: 20,000 rpm Processing feed rate: 100mm / s Cutting water supply rate: 2.0L / min Cutting blade temperature: 70℃

[0139] The heating and cooling mechanism 110 may be capable of only heating or only cooling the cutting fluid 64a before it is supplied to the cutting blade 54 and the workpiece 11.

[0140] When only heating can be performed, the cutting fluid 64a is not heated in the first cutting step S10, but is heated in the second cutting step S20. As a result, the outer periphery 54b of the cutting blade 54 has a relatively small first thickness 54d1 in the first cutting step S10 (see FIG. 9A), and a relatively large second thickness 54d2 in the second cutting step S20 (see FIG. 10A).

[0141] When only cooling can be performed, the cutting fluid 64a is cooled in the first cutting step S10, but not in the second cutting step S20. As a result, the thickness 54b1 of the outer periphery 54b of the cutting blade 54 is set to a relatively small first thickness 54d1 in the first cutting step S10 (see FIG. 9A), and to a relatively large second thickness 54d2 in the second cutting step S20 (see FIG. 10A).

[0142] Furthermore, the cutting device 2 of the third embodiment further includes, in addition to the heating / cooling mechanism 110, a flow rate adjustment mechanism (not shown) such as a valve or a pump provided in the flow path 108. In other words, the heating / cooling mechanism 110 and the flow rate adjustment mechanism constitute a temperature adjustment unit.

[0143] Since heat is generated at the processing point of the cutting blade 54 during cutting, if the flow rate of the cutting fluid 64a at a predetermined temperature (e.g., 20°C) is set to a first flow rate (e.g., 2.0 L / min), the heat generated during cutting is substantially removed. Therefore, changes in the blade thickness of the cutting blade 54 are suppressed. For example, in the first cutting step S10, the flow rate of the cutting fluid 64a is set to the first flow rate.

[0144] In contrast, if the flow rate of the cutting fluid 64a at a predetermined temperature (e.g., 20°C) is set to a second flow rate (e.g., 0.5 L / min) that is lower than the first flow rate, the generated heat is not sufficiently removed and gradually accumulates in the cutting blade 54, causing the temperature of the cutting blade 54 to rise over time.

[0145] This allows the thickness of the cutting blade 54 to be relatively large. For example, in the second cutting step S20, the flow rate of the cutting fluid 64a is set to the second flow rate. In the third embodiment, either or both of the heating / cooling mechanism 110 and the flow rate adjustment mechanism may be used.

[0146] In the third embodiment, in the first cutting step S10, the thickness 54b1 of the outer peripheral portion 54b of the cutting blade 54 can be set to a relatively small first thickness 54d1 (see Figure 9(A)), and in the second cutting step S20, the thickness 54b1 of the outer peripheral portion 54b of the cutting blade 54 can be set to a relatively large second thickness 54d2 (see Figure 10(A)).

[0147] (Fourth embodiment) Next, a fourth embodiment will be described with reference to Figures 13 to 14(B) Fig. 13 is a partially cross-sectional side view of a cutting unit 42 in the fourth embodiment.

[0148] An annular resin layer 56d made of synthetic resin is provided on the flange surface of the receiving flange portion 56. The resin layer 56d comes into contact with the cutting blade 54 when the cutting blade 54 is clamped between the receiving flange portion 56 and the pressing flange portion 58.

[0149] An annular piezoelectric element 112a is provided between the flange surface and the boss portion 56a in the radial direction of the receiving flange portion 56. The piezoelectric element 112a is fixed to the receiving flange portion 56.

[0150] An annular resin layer 58b made of synthetic resin is also provided on the flange surface of the pressing flange portion 58. The resin layer 58b also comes into contact with the cutting blade 54 when the cutting blade 54 is clamped between the receiving flange portion 56 and the pressing flange portion 58.

[0151] An annular piezoelectric element 112b is provided radially inward of the flange surface of the retaining flange portion 58. The piezoelectric element 112b is fixed to the retaining flange portion 58. In this manner, the piezoelectric elements 112a and 112b are provided in the cutting blade holding portion 62.

[0152] The piezoelectric elements 112a and 112b are electrostrictive and include piezoelectric ceramics such as barium titanate, lead zirconate titanate, etc. The piezoelectric elements 112a and 112b are expandable and contractible along the radial direction of the cutting blade holding portion 62 (the Z-axis direction in FIG. 13).

[0153] An AC voltage is applied to the piezoelectric elements 112a and 112b via a rotary transformer 114. The rotary transformer 114 includes a power supply unit 116 fixed to the spindle housing 44 and including an annular coil 116a, and a power receiving unit 118 fixed to the spindle 46 and including an annular coil 118a.

[0154] In this way, the power supply unit 116 and the power receiving unit 118 are provided in the cutting unit 42. In this embodiment, the piezoelectric elements 112a and 112b, the power supply unit 116, the power receiving unit 118, etc. function as an ultrasonic vibration generating unit (i.e., an external stimulus applying unit) for changing the thickness of the cutting blade 54.

[0155] An AC power supply unit 122 such as a high-speed bipolar power supply is connected to the power supply unit 116 via wires 120a and 120b. A signal generator 124 that controls the frequency of the supplied AC voltage is also connected to the AC power supply unit 122.

[0156] The operations of the AC power supply unit 122, the signal generator 124, etc. are controlled by the above-mentioned controller 100. The controller 100 controls the AC power supply unit 122, etc., to apply an AC voltage from the AC power supply unit 122 to the piezoelectric elements 112a and 112b, thereby controlling the displacement, vibration, etc. in the Y-axis direction of the piezoelectric elements 112a and 112b.

[0157] For example, the controller 100 applies an AC voltage in an ultrasonic frequency band (e.g., several tens of kHz) to the piezoelectric elements 112a and 112b from the AC power supply unit 122. This causes the piezoelectric elements 112a and 112b to vibrate so as to expand and contract along the radial direction of the cutting blade 54 (i.e., perform a periodic operation).

[0158] 14(A) is a side view of the cutting blade 54 in the first cutting step S10 of the fourth embodiment. In the first cutting step S10, the thickness of the entire cutting blade 54 is set to the first thickness 54d1 without applying a voltage to the piezoelectric elements 112a and 112b. An example of processing conditions for the first cutting step S10 in the fourth embodiment is shown below.

[0159] Overall blade thickness (normal value): 300 μm Spindle rotation speed: 20,000 rpm Processing feed rate: 50mm / s Cutting water supply rate: 2.0L / min Vibration frequency of piezoelectric element: 0 kHz (i.e., no AC voltage applied)

[0160] On the other hand, in the second cutting step S20, the controller 100 applies an AC voltage in the ultrasonic frequency band from the AC power supply unit 122 to the piezoelectric elements 112a and 112b, thereby generating ultrasonic vibrations in the piezoelectric elements 112a and 112b.

[0161] The ultrasonic vibrations of the piezoelectric elements 112a and 112b are transmitted to the cutting blade 54 via the receiving flange portion 56 and the pressing flange portion 58. That is, in the second cutting step S20, the cutting blade 54 can be periodically elastically deformed.

[0162] 14(B) is a side view of the cutting blade 54 in the second cutting step S20 of the fourth embodiment. As shown by the solid line in FIG. 14(B), when the length in the Z-axis direction becomes a relatively small diameter 54e2, the cutting blade 54 elongates in the Y-axis direction, and the thickness of the entire cutting blade 54 becomes a relatively large second thickness 54d2.

[0163] In contrast, as shown by the dashed line in Figure 14(B), when the length in the Z-axis direction becomes a relatively large diameter 54e3, the cutting blade 54 is compressed in the Y-axis direction, and the overall thickness of the cutting blade 54 becomes a relatively small thickness 54d3.

[0164] In the second cutting step S20, in which the thickness of the entire cutting blade 54 is periodically changed using the frequency of ultrasonic vibrations, at least the burrs 21a generated on the intended division line 17 in the first cutting step S10 can be removed at the timing when the thickness of the entire cutting blade 54 becomes the second thickness 54d2 that is larger than the first thickness 54d1. An example of processing conditions for the second cutting step S20 in the fourth embodiment is shown below.

[0165] Overall blade thickness (maximum): 301 μm Spindle rotation speed: 20,000 rpm Processing feed rate: 100mm / s Cutting water supply rate: 2.0L / min Piezoelectric element vibration frequency: 40kHz

[0166] In the fourth embodiment, an example has been described in which an AC voltage is applied to the piezoelectric elements 112a and 112b to cause ultrasonic vibration. However, a DC voltage may be applied to the piezoelectric elements 112a and 112b from a DC power supply unit (not shown) by using a slip ring (not shown).

[0167] While a DC voltage is applied, the piezoelectric elements 112a and 112b operate to maintain an expanded or compressed state along the Y axis (that is, to be in a steady state).

[0168] For example, by not applying a DC voltage to the piezoelectric elements 112a and 112b in the first cutting step S10 and applying a DC voltage to the piezoelectric elements 112a and 112b in the second cutting step S20, the cutting blade 54 is extended in the Y-axis direction in the second cutting step S20 compared to the first cutting step S10. This allows the overall thickness of the cutting blade 54 in the second cutting step S20 to be greater than the overall thickness of the cutting blade 54 in the first cutting step S10.

[0169] Also, for example, in the first cutting step S10, a DC voltage is applied to the piezoelectric elements 112a and 112b to compress the cutting blade 54 in the Y-axis direction, and in the second cutting step S20, a DC voltage is not applied to the piezoelectric elements 112a and 112b. This allows the overall thickness of the cutting blade 54 in the second cutting step S20 to be greater than the overall thickness of the cutting blade 54 in the first cutting step S10.

[0170] In addition, the structures, methods, etc. according to the above-described embodiments can be appropriately modified and implemented without departing from the scope of the present invention. For example, the cutting method described above is not necessarily limited to the order of the first cutting step S10 and the second cutting step S20. For example, cutting of the workpiece 11 may be carried out as follows.

[0171] First, a first cutting step S10 is performed on each of the division lines 17 in the first direction, and then a second cutting step S20 is performed on each of the division lines 17 in the first direction. Thereafter, the chuck table 18 is rotated by 90 degrees.

[0172] Then, a first cutting step S10 is performed on each of the planned division lines 17 in the second direction, and then a second cutting step S20 is performed on each of the planned division lines 17 in the second direction. In this case, too, at least the burrs 21a generated on the planned division lines 17 in the first cutting step S10 can be removed in the second cutting step S20 using a single cutting blade 54 without using a covering member.

[0173] Incidentally, in the above-described first cutting step S10, the workpiece 11 is cut (that is, fully cut) at a position where the lower end of the cutting blade 54 reaches the dicing tape 23, but this is not necessarily required.

[0174] In the first cutting step S10, the lower end of the cutting blade 54 may be set to a predetermined depth that does not reach the back surface 11b, and the workpiece 11 may be cut to form a so-called half-cut groove. In this case, the workpiece 11 is cut to a depth that reaches the dicing tape 23 for the first time in the second cutting step S20.

[0175] Note that forming a half-cut groove does not necessarily mean that the bottom surface of the first cut groove 11c1 is positioned exactly halfway through the thickness of the workpiece 11 (i.e., the length from the front surface 11a to the back surface 11b).

[0176] Forming a half-cut groove means that the bottom surface of the first cut groove 11c1 does not reach the dicing tape 23. The bottom surface of the first cut groove 11c1 may be located in the semiconductor package substrate 13 or in the molded resin layer 19 in the thickness direction of the workpiece 11.

[0177] When the first cutting groove 11c1 is a half-cut groove, the workpiece 11 is not naturally divided into multiple chips (i.e., semiconductor packages) in the first cutting step S10, and the workpiece 11 remains integrally connected by the semiconductor package substrate 13, molded resin layer 19, etc.

[0178] Therefore, compared to when full-cut grooves are formed on all planned dividing lines 17 in the first cutting step S10 and the workpiece 11 is divided into multiple chips, it is possible to prevent misalignment of the planned dividing lines 17, rectangular areas 17a, etc. at the end of the first cutting step S10.

[0179] As a result of preventing misalignment, the cutting blade 54 can be positioned more accurately in the first cutting groove 11c1 in the second cutting step S20, so that the burrs 21a can be removed more reliably by the cutting blade 54 compared to when the workpiece 11 is divided into multiple chips in the first cutting step S10.

[0180] In addition, if the workpiece 11 has already been divided into multiple chips in the first cutting step S10, in the second cutting step S20, cutting loads are applied to each chip arranged on both sides of one planned division line 17, which may cause each chip to move slightly after burr 21a has been removed.

[0181] As a result of the chip moving, when removing the burrs 21a of each chip located on both sides of another planned division line 17 located next to the one planned division line 17, areas of the chip that were not intended to be cut may be cut, resulting in the production of a chip with a shape different from the intended shape.

[0182] In contrast, if the first cutting groove 11c1 is a half-cut groove, the movement of the chip when removing the burr 21a is suppressed, thereby reducing the variation in the shape of the chip that is finally manufactured compared to when the first cutting groove 11c1 is a full-cut groove. [Explanation of symbols]

[0183] 2: Cutting device, 4: Base, 4a: Top surface, 4b: Support structure 6: X-axis direction moving unit, 8: guide rail, 10: X-axis direction moving plate, 12: screw shaft 11: Workpiece, 11a: Front surface, 11b: Back surface 11c1: first cutting groove, 11c2: second cutting groove 13: semiconductor package substrate, 13a: peripheral excess area, 13b: non-device area 14: driving source, 16: support part 15a, 15b, 15c: device area, 17: planned division line, 17a: rectangular area 18: chuck table (holding table), 18a: holding surface, 20: clamp unit 19: molded resin layer, 21: metal terminal, 21a: burr 22: Y-axis direction moving unit, 24: guide rail, 26: Y-axis direction moving plate 23: dicing tape, 25: annular frame, 27: workpiece unit 28: screw shaft, 30: drive source 32: Z-axis direction moving unit, 34: guide rail, 36: Z-axis direction moving plate 38: screw shaft, 40: drive source 42: Cutting unit, 44: Spindle housing 46: Spindle, 46a: Washer, 46b: Bolt 48: Motor, 50: Rotation drive unit (external stimulus applying unit), 52: Stator 54: Cutting blade 54b: outer periphery, 54b1: thickness 54c: inner circumference, 54c1: thickness 54d1: first thickness, 54d2: second thickness, 54d3: thickness, 54e2, 54e3: diameter 56: Receiving flange portion, 56a: Boss portion, 56b: Male thread 56c: Groove, 56d: Resin layer 58: Pressing flange portion, 58a: Through hole, 58b: Resin layer 60: Presser nut, 60a: Female thread 62: Cutting blade holder 64: Blade cover, 64a: Cutting fluid 66: Upper cover part, 68: First cover part, 70: Arm part, 70a: Cooler nozzle 72: second cover part, 72a: shower nozzle, 72b: spray nozzle 74: Cutting fluid supply nozzle, 76: Cutting fluid supply source 80: Microscope camera unit 82: Blade position detection unit, 84: Detector, 84a: Support part, 84b: Detection part 86: Light emitting unit, 88: Light receiving unit, 90: First nozzle, 92: Second nozzle 94: Connector, 96: Cover 100: Controller, 100a: Processor, 100b: Memory 102: Heating wire (temperature control unit, external stimulus application unit) 104: Heater (temperature control unit, external stimulus applying unit) 106: Peltier element (temperature control unit, external stimulus application unit) 106a: 1st side, 106b: 2nd side 108: flow path, 110: heating and cooling mechanism (temperature control unit, external stimulus applying unit) 112a, 112b: piezoelectric elements 114: Rotary transformer 116: power supply unit, 116a: coil 118: power receiving unit, 118a: coil 120a, 120b: Wiring 122: AC power supply unit, 124: signal generator L: Light, S10: 1st cutting process, S20: 2nd cutting process

Claims

1. a first cutting step of cutting the workpiece held by the holding table with a cutting blade along a predetermined dividing line set on the workpiece; a second cutting step in which the thickness of the cutting blade is set to a second thickness greater than the first thickness of the cutting blade in the first cutting step, and the workpiece is cut along the intended dividing line with the cutting blade having the second thickness, thereby removing at least burrs generated on the intended dividing line in the first cutting step; Equipped with A cutting method characterized in that the difference between the first thickness and the second thickness is obtained by applying an external stimulus to the cutting blade in the first cutting step or the second cutting step.

2. a holding table for holding the workpiece; a cutting unit having a spindle for cutting the workpiece held by the holding table with a cutting blade attached to the spindle; an external stimulus applying unit that applies an external stimulus to the cutting blade to change the thickness of the cutting blade; a controller that controls at least the operations of the cutting unit and the external stimulus applying unit; Equipped with the controller, when the thickness of the cutting blade is a first thickness in a first cutting step in which the workpiece held by the holding table is cut with the cutting blade along a predetermined dividing line set on the workpiece, sets the thickness of the cutting blade to a second thickness greater than the first thickness in a second cutting step in which at least burrs generated along the predetermined dividing line in the first cutting step are removed; A cutting device characterized in that the difference between the first thickness and the second thickness is obtained by applying an external stimulus to the cutting blade in the first cutting step or the second cutting step.

3. the external stimulus applying unit is a rotation driving unit provided in the cutting unit and having a motor that rotates the spindle, The cutting device according to claim 2, wherein the controller reduces the rotational speed of the spindle in the second cutting process compared to the first cutting process, thereby setting the thickness of the cutting blade to the second thickness greater than the first thickness.

4. the external stimulus applying unit has a temperature adjusting unit that performs at least one of heating and cooling on the cutting blade; The cutting device according to claim 2, characterized in that the controller controls the temperature control unit to increase the temperature of the cutting blade in the second cutting process compared to the first cutting process, thereby setting the thickness of the cutting blade to the second thickness greater than the first thickness.

5. the cutting unit has a cutting blade holding portion for mounting the cutting blade on the spindle in a state where the cutting blade is sandwiched in the thickness direction of the cutting blade; The temperature adjustment unit is provided in the cutting blade holding portion, 5. The cutting device according to claim 4, wherein the temperature adjustment unit performs at least one of heating and cooling of the cutting blade by heat conduction through the cutting blade holder.

6. 5. The cutting device according to claim 4, wherein the temperature adjustment unit includes a heater fixed to the cutting unit and disposed adjacent to the cutting blade to supply heat to the cutting blade.

7. the cutting unit has a cutting fluid supply nozzle that supplies cutting fluid to the cutting blade and the workpiece; The cutting device described in claim 4, characterized in that the temperature adjustment unit is provided in a flow path that supplies the cutting fluid to the cutting fluid supply nozzle, and performs at least one of heating and cooling of the cutting fluid before it is supplied to the cutting blade and the workpiece.

8. the cutting unit has a cutting blade holding portion for mounting the cutting blade on the spindle in a state where the cutting blade is sandwiched in the thickness direction of the cutting blade; the external stimulus applying unit includes a piezoelectric element provided in the cutting blade holding unit, and a power supply unit provided in the cutting unit and having a coil for applying a voltage to the piezoelectric element; The cutting device according to claim 2, wherein the controller operates the piezoelectric element to set the thickness of the cutting blade to the second thickness, which is greater than the first thickness, in the second cutting process.

9. the external stimulus applying unit is an ultrasonic vibration generating unit including the piezoelectric element and the power supply unit, The cutting device according to claim 8, characterized in that in the second cutting process, the controller periodically causes the ultrasonic vibration generating unit to generate ultrasonic vibrations, thereby causing the thickness of the cutting blade to be the second thickness, which is greater than the first thickness.

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