Cutting device

Abstract

Cutting device (2) comprising: a clamping table (18) for holding a workpiece; a cutting device (26) for cutting the workpiece held on the clamping table (18); and a feeding means for the relative feeding of the clamping table (18) and the cutting means (26); wherein the cutting means (26) comprises a spindle (28), a spindle housing (27) for rotatably holding the spindle (28), a retaining flange (46) attached to the front end section of the spindle (28), a cutting blade (30) detachably held on the retaining flange (46) and a fastening flange (64) for fastening the cutting blade (30) held on the retaining flange (46); wherein the retaining flange (46) includes a hub section (48) designed to be inserted through a central opening (30a) of the cutting blade (30), a flange section (50) formed integrally with the outer circumference of the hub section (48) for holding a side surface of the cutting blade (30) and a cylindrical section (53) for engaging with the front end section of the spindle (28); wherein the flange section (50) of the retaining flange (46) is formed with an intake opening (60) which opens towards the mounting flange (64), and the cylindrical section (53) of the retaining flange (46) is formed with a connecting opening (56) which is connected to the intake opening (60); wherein the connecting opening (56) is connected to a vacuum source (74) by means of a rotary connection (36) attached to the spindle housing (27), such that the connection between the connecting opening (56) and the vacuum source (74) is selectively established by an on / off valve (72), whereby, when the on / off valve (72) is opened to establish the connection between the connecting opening (56) and the vacuum source (74), a reduced pressure is applied between the retaining flange (46) and the mounting flange (64) in order to draw the mounting flange (64) towards the retaining flange (46), so that the cutting blade (30) is secured between the retaining flange (46) and the mounting flange (64); wherein a rotation restriction section (48, 52) is formed on the outer circumference of the hub section (48) of the retaining flange (46) and on the inner surface of an engagement opening (65) of the mounting flange (64) for engagement with the hub section (48) to restrict a relative rotation of the retaining flange (46) and the mounting flange (64).

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a cutting device for cutting a workpiece, such as a semiconductor wafer, and more specifically to an attachment mechanism for a cutting blade in the cutting device. Description of the state of the art

[0002] Multiple components, such as ICs and LSIs, are each formed in several separate areas, defined by multiple dividing lines on the front face of a semiconductor wafer. The semiconductor wafer, thus containing these multiple components, is divided into individual component chips using a cutting device with a cutting blade. These component chips are widely used in various electronic devices, such as mobile phones and PCs. The cutting device includes a clamping table for holding the workpiece, a cutting element for cutting the workpiece held on the clamping table, and a feeding device for the relative feeding of the clamping table and the cutting element, enabling the workpiece, such as a wafer, to be divided into individual component chips with high precision.

[0003] The cutting device includes a spindle designed to be driven by a motor, a spindle housing for rotatably holding the spindle, a retaining flange attached to the front end section of the spindle, a removable cutting blade held on the retaining flange, and a mounting flange for attaching the cutting blade held on the retaining flange.The retaining flange has a hub section designed to be inserted through a central opening in the cutting blade, a flange section formed integrally with the outer circumference of the hub section for holding a side surface of the cutting blade, and an external screw thread formed at the front end of the hub section, wherein the cutting blade and the mounting flange (pressure flange) are attached to the hub section of the retaining flange, and a nut is engaged with the external screw thread of the hub section of the retaining flange until tightened, thereby holding the cutting blade securely between the retaining flange and the mounting flange (see, for example, JP H11-33907A).

[0004] JP 2002 - 154 054 A relates to an attachment mechanism for a cutting blade which is able to prevent the cutting blade from falling off by ensuring a holding force for the cutting blade regardless of the direction of rotation of the rotating shaft. SUMMARY OF THE INVENTION

[0005] Generally, the helical structure of the screw threads on the retaining flange and the nut is oriented opposite to the spindle's direction of rotation to prevent the mounting flange from loosening due to the spindle's rotation during the cutting process. Accordingly, as the cutting process continues, the nut is tightened securely to the outer screw thread of the retaining flange without loosening. Consequently, if the cutting blade needs to be replaced, considerable torque is required to remove the nut. However, when the cutting blade becomes worn or chipped, it must be replaced with a new one, and this replacement of the cutting blade with respect to the retaining flange is performed relatively frequently.With the conventional attachment structure for the cutting blade, a large torque is required to remove the nut, as described above, so there is a problem in that manufacturing efficiency may be reduced.

[0006] It is therefore an objective of the present invention to provide a cutting device that enables an operator to effectively replace the cutting blade with respect to the holding flange.

[0007] According to one aspect of the present invention, a cutting device is provided comprising: a clamping table for holding a workpiece; a cutting means for cutting the workpiece held on the clamping table; and a feeding means for the relative feeding of the clamping table and the cutting means; wherein the cutting means comprises a spindle, a spindle housing for rotatably holding the spindle, a retaining flange attached to the front end section of the spindle, a cutting blade detachably held on the retaining flange, and a mounting flange for securing the cutting blade held on the retaining flange;wherein the retaining flange comprises a hub section configured to be inserted through a central opening of the cutting blade, a flange section formed integrally with the outer circumference of the hub section for holding a side surface of the cutting blade, and a cylindrical section for engaging with the front end section of the spindle; wherein the flange section of the retaining flange is configured with an intake opening opening towards the mounting flange, and the cylindrical section of the retaining flange is configured with a connecting opening that communicates with the intake opening;wherein the connecting opening is connected to a vacuum source by means of a rotary joint attached to the spindle housing, such that the connection (communication) between the connecting opening and the vacuum source can be selectively established by an on / off valve, whereby, when the on / off valve is opened to establish the connection (communication) between the connecting opening and the vacuum source, a reduced pressure is applied between the retaining flange and the mounting flange to draw the mounting flange towards the retaining flange, so that the cutting blade is secured between the retaining flange and the mounting flange;wherein a rotation restriction section is formed to restrict a relative rotation of the retaining flange and the mounting flange on the outer circumference of the hub section of the retaining flange and on the inner surface of an engagement opening of the mounting flange for engagement with the hub section.

[0008] Preferably, the cutting device further includes a pressure gauge provided between the rotary joint and the vacuum source for measuring the reduced pressure; and a safety unit for issuing a danger signal when the reduced pressure measured by the pressure gauge becomes greater than a predetermined value.

[0009] According to the present invention, the on / off valve is opened to establish a connection (communication) between the suction port and the vacuum source during the cutting process. As a result, the mounting flange is drawn towards the holding flange, thereby holding the cutting blade firmly between the holding flange and the mounting flange under suction. When the cutting blade is replaced, the on / off valve is closed to release the suction holding of the mounting flange. Consequently, the mounting flange can be easily removed from the holding flange, allowing the cutting blade to be effectively replaced with a new one.

[0010] The above and further aims, features and advantages of the present invention and the manner in which they are realized will become more apparent, and the invention itself will be best understood by studying the following description and the attached claims with reference to the accompanying drawings, which show a preferred embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view of a cutting device according to a preferred embodiment of the present invention; Fig. Figure 2 is a perspective view of a single part, showing one way of attaching a retaining flange to the front end section of a spindle; Fig. 3A is a perspective view of a single component, showing one way of attaching a cutting blade to the holding flange with a mounting flange; Fig. 3B is a perspective view of the mounting flange from its rear side; Fig. 4A is a perspective view showing a state in which the cutting blade and the mounting flange are attached to the holding flange; and Fig. 4B is a cross-sectional view of the Fig. 4A along the axis of the spindle. DETAILED DESCRIPTION OF THE PREFERRED EXECUTION FORM

[0011] A preferred embodiment of the present invention is described in detail below with reference to the drawings. Fig. Figure 1 shows a perspective view of a cutting device 2, which includes an attachment mechanism for a cutting blade according to this preferred embodiment. The cutting device 2 includes an operating panel 4 to enable an operator to input instructions, such as processing conditions, into the device 2. The operating panel 4 is located on the front section of the cutting device 2. The cutting device 2 also includes a display unit 6, such as a CRT, for displaying a guide view for the operator or an image obtained by an imaging unit, which is described below. The display unit 6 is located on the upper section of the cutting device 2.

[0012] A semiconductor wafer (hereinafter also referred to simply as a wafer) 11 is a workpiece to be cut by the cutting device 2. The wafer 11 is first attached to a slicing belt T, which is held on an annular frame F. Several such wafers 11, each held on the annular frame F by the slicing belt T, are stored in a wafer cassette 8. The wafer cassette 8 is arranged on a vertically movable cassette lifting device 9. A wafer handling unit 10 is provided at the rear of the wafer cassette 8 to remove a desired wafer 11 from the cassette 8 before cutting and also to return the wafer 11 to the cassette 8 after cutting.

[0013] A transition area 12 for temporarily arranging the wafer 11 to be handled by the wafer handling unit 10 is provided between the wafer cassette 8 and the wafer handling unit 10. A positioning mechanism (a pair of centering guides) 14 for positioning the wafer 11 at a fixed location is provided in the transition area 12. A first transfer unit 16 with a pivoting arm for transferring the wafer 11, which is held under suction, is provided near the transition area 12. The wafer 11, removed from the wafer cassette 8 and positioned in the transition area 12, is transferred by the first transfer unit 16 to a clamping table 18. The wafer 11, once transferred to the clamping table 18, is held under suction on the clamping table 18.

[0014] The clamping table 18 is rotatable by a motor (not shown) and movable in the X-direction by a feeding mechanism (not shown). An alignment unit 22 for detecting a target area of ​​the wafer 11 to be cut is provided above the movement path of the clamping table 18 in the X-direction. The clamping table 18 is equipped with several clamps 20 for clamping the annular frame F, which holds the wafer 11 held on the clamping table 18. The alignment unit 22 includes an imaging unit 24 for imaging the front face of the wafer 11. Based on an image obtained by the imaging unit 24, the alignment unit 22 can detect the target area of ​​the wafer 11 by performing image processing, such as pattern matching. The image obtained by the imaging unit 24 is displayed by the display unit 6.

[0015] A cutting unit 26 for cutting the wafer 11 held on the clamping table 18 is considered in the Fig. 1 is provided on the left side of the alignment unit 22. The cutting unit 26 is integrated with the alignment unit 22 so that they are movable together in the Y and Z directions. The cutting unit 26 includes a rotatable spindle 28 and a cutting blade 30 attached to the front end of the spindle 28. The cutting unit 26 is movable in the Y and Z directions. The cutting blade 30 is arranged on a line of extension that extends from the imaging unit 24 in the X direction. The movement of the cutting unit 26 in the Y direction is achieved by a indexing mechanism (not shown).

[0016] Reference numeral 34 designates a centrifugal cleaning unit for cleaning the wafer 11 after cutting. After cutting, the wafer 11 is transferred from the clamping table 18 to the centrifugal cleaning unit 34 by a second transfer unit 32 and subsequently subjected to centrifugal cleaning and centrifugal drying in the centrifugal cleaning unit 34.

[0017] Fig. Figure 2 is a perspective view of a single component, showing one way of attaching a retaining flange 46 to the front end section of the spindle 28. The spindle 28 of the cutting unit 26 is rotatably mounted on a spindle housing 27 by an air bearing. The spindle 28 has a tapered section 28a and a small-diameter section 28b extending from the front end of the tapered section 28a. The small-diameter section 28b is formed with an external screw thread 31. The external screw thread 31 has a helical structure that is opposite to the direction of rotation of the spindle 28. The spindle housing 27 has an end surface 27a from which the spindle 28 projects. The end surface 27a of the spindle housing 27 is formed with several openings 29 with internal threads.

[0018] Reference numeral 36 designates a rotary joint consisting of a cylindrical hub section 38 and a flange section 40, which is formed integrally with the outer circumference of the hub section 38. The hub section 38 has an insertion opening 38a and a tube 42, which has an end that opens towards the insertion opening 38a. As shown in Fig. As shown in Figure 3A, the tube 42 is connected to a vacuum source 74 in such a way that the connection (communication) between the tube 42 and the vacuum source 74 is selectively established by an on / off valve 72. The flange section 40 of the rotary joint 36 is provided with several mounting openings 41. Several screws 44 are inserted through the mounting openings 41 of the rotary joint 36 and engaged with the threaded openings 29 formed on the end surface 27a of the spindle housing 27 until they are tightened, thereby securing the rotary joint 36 to the end surface 27a of the spindle housing 27.

[0019] Reference numeral 46 designates a retaining flange for holding the cutting blade 30. The retaining flange 46 consists of a hub section 48 with an engagement opening 49, a flange section 50 formed integrally with the outer circumference of the hub section 48, and a cylindrical section 53 designed to engage with the front end section of the spindle 28. The outer circumference of the hub section 48 is formed with several projections 52, which are uniformly spaced from one another in the circumferential direction of the hub section 48. The flange section 50 has a retaining surface 50a and an annular groove 58. The retaining surface 50a is designed to bear against a side surface of the cutting blade 30 through which the hub section 48 is inserted, thereby holding the cutting blade 30. Several suction openings 60 open to the bottom of the annular groove 58.The multiple intake openings 60 are evenly spaced apart from each other in the circumferential direction of the annular groove 58.

[0020] The cylindrical section 53 of the retaining flange 46 is formed with an annular groove 54. Several connecting openings 56 open to the bottom of the annular groove 54. The several connecting openings 56 are evenly spaced from one another in the circumferential direction of the annular groove 54. As can be seen from the Fig. As can be seen in Figure 4B, the intake openings 60 and the connecting openings 56 are connected to each other by several connecting passages 57 formed in the hub section 50 and the cylindrical section 53.

[0021] As in Fig. As shown in Figure 3A, a pressure gauge 76 is provided in an intake port 71 that connects the tube 42 and the vacuum source 74. The pressure gauge 76 is connected to a control unit (safety unit) 78. When the on / off valve 72 is opened, a vacuum is created by the vacuum source 74 in a section of the intake port 71 between the tube 42 and the on / off valve 72. This vacuum is measured by the pressure gauge 76. If the pressure measured by the pressure gauge 76 exceeds a predetermined value (for example, 0.02 MPa), the control unit 78, which has suitable software, determines that a hazard exists and then issues a hazard signal to immediately stop the cutting process. Since atmospheric pressure is 0.1 MPa, the predetermined value of 0.02 MPa represents a vacuum.

[0022] After the retaining flange 46 has engaged with the tapered section 28a and the small-diameter section 28b of the spindle 28, a nut 62 is screwed into the external thread 31 of the spindle 28 until it is tightened, thereby securing the retaining flange 46 to the front end section of the spindle 28, as shown in Fig. Figure 3A shows that after the retaining flange 46 has been attached to the front end section of the spindle 28, the hub section 48 of the retaining flange 46 is inserted through a central opening 30a of the cutting blade 30. A mounting flange (pressure flange) 64 with an engagement opening 65 is then attached to the hub section 48 of the retaining flange 46. That is, the hub section 48 of the retaining flange 46 is inserted tightly through the engagement opening 65 of the mounting flange 64 when the cutting blade 30 is positioned between the retaining flange 46 and the mounting flange 64. The cutting blade 30 is a disc blade, such as a resin blade, which is obtained by bonding diamond abrasive grains with a resin bond, a ceramic bond blade, which is obtained by bonding diamond abrasive grains with a ceramic bond, and an electroformed blade, which is obtained by bonding diamond abrasive grains with a nickel plating.

[0023] Several recesses 70 are formed on the inner circumference of the engagement opening 65 of the mounting flange 64 such that they are evenly spaced from one another in the circumferential direction of the mounting flange 64. The several recesses 70 of the mounting flange 64 each correspond to the several projections 52 formed on the hub section 48 of the retaining flange 46. When attaching the mounting flange 64 to the hub section 48 of the retaining flange 46, the mounting flange 64 is positioned in the circumferential direction such that the recesses 70 engage with the projections 52. The hub section 48 of the retaining flange 46 is then inserted through the engagement opening 65 of the mounting flange 64.Accordingly, the projections 52 of the retaining flange 46 and the recesses 70 of the mounting flange 64 work together to form a rotation restriction section for limiting the relative rotation of the retaining flange 46 and the mounting flange 64. Fig. Figure 3B is a perspective view showing the rear side of the mounting flange 64. As in Fig. As shown in Figure 3B, the mounting flange 64 has an annular retaining surface 66 for holding the inner circumference of the cutting blade 30, through which the hub section 48 of the retaining flange 46 is inserted, and a pressure surface 68 for pressing the other side surface of the cutting blade 30.

[0024] Fig. Figure 4A is a perspective view showing a state in which the cutting blade 30 and the mounting flange 64 are attached to the hub section 48 of the retaining flange 46, and Fig. 4B is a cross-sectional view of the Fig. 4A along the axis of spindle 28. If that is in Fig. When the on / off valve 72 shown in Figure 3A is opened to establish the connection between the tube 42 and the vacuum source 74, a vacuum is applied through the annular groove 54, the connecting openings 56, the connecting passages 57, and the suction openings 60 of the cylindrical section 53 of the retaining flange 46 onto the annular groove 58 of the retaining flange 46, so that the mounting flange 64 is drawn towards the retaining flange 46. Accordingly, the cutting blade 30 is held firmly between the holding surface 50a of the flange section 50 of the retaining flange 46 and the pressure surface 68 of the mounting flange 64.

[0025] If the pressure measured by the pressure gauge 76 in the intake passage 71 is less than or equal to the specified value mentioned above, the vacuum applied to the annular groove 58 of the flange section 50 is sufficiently large to hold the cutting blade 30 firmly between the retaining surface 50a of the flange section 50 and the pressure surface 58 of the mounting flange 64 by a sufficiently strong suction force. Accordingly, no problems occur when cutting a workpiece with the cutting blade 30. However, if the pressure in the intake passage 71 exceeds the specified value mentioned above, the vacuum applied to the annular groove 58 of the flange section 50 becomes insufficient, and the retention of the cutting blade 30 becomes inadequate if the cutting process continues.Accordingly, the control unit 78 issues a danger signal if the pressure gauge 76 detects a pressure greater than the specified value, in order to immediately stop the cutting process for the workpiece.

[0026] If the cutting blade 30 is worn or chipped and needs to be replaced, the on / off valve 72 is closed to interrupt the vacuum applied to the annular groove 58 of the flange section 50. Accordingly, the vacuum holding the mounting flange 64 is released, allowing the mounting flange 64 and the cutting blade 30 to be easily removed from the hub section 48 of the retaining flange 46.

[0027] According to a feature of the cutting blade attachment mechanism in this preferred embodiment, the rotary joint 36 is used to introduce a vacuum. That is, by attaching the rotary joint 36 to the end surface 27a of the spindle housing 27, a vacuum can be introduced into the annular groove 58 of the flange section 50 of the retaining flange 46. Accordingly, it is not necessary to significantly modify the structure of the spindle and spindle housing in a conventional cutting device; rather, it is only necessary to slightly modify the end surface of the spindle housing in the conventional cutting device. This allows the fastening of the mounting flange 64, which is currently achieved using a nut in the conventional cutting device, to be easily changed to fastening by vacuum.

[0028] In the preferred embodiment described above, a vacuum is introduced through the rotary joint 36 into the annular groove 58 formed on the flange section 50 of the retaining flange 46, thereby holding the cutting blade 30 firmly between the retaining surface 50a of the flange section 50 of the retaining flange 46 and the pressure surface 68 of the mounting flange 64. Furthermore, the projections 52 formed on the hub section 48 of the retaining flange 46 engage with the recesses 70 formed on the inner surface of the engagement opening 65 of the mounting flange 64, thus forming the rotation limitation section. Accordingly, the cutting blade 30 can be reliably secured between the retaining flange 46 and the mounting flange 64 without the use of a nut.If the cutting blade 30 is replaced, the mounting flange 64 can be easily removed from the retaining flange 46 by closing the on / off valve 72, so that the cutting blade 30 can effectively be replaced with a new one.

[0029] The present invention is not limited to the details of the preferred embodiment described above. The scope of the invention is defined by the attached claims, and all modifications and variations that fall within the equivalence of the scope of the claims are therefore included in the invention.

Claims

[1] Cutting device (2) comprising: a clamping table (18) for holding a workpiece; a cutting device (26) for cutting the workpiece held on the clamping table (18); and a feeding means for the relative feeding of the clamping table (18) and the cutting means (26); wherein the cutting means (26) comprises a spindle (28), a spindle housing (27) for rotatably holding the spindle (28), a retaining flange (46) attached to the front end section of the spindle (28), a cutting blade (30) detachably held on the retaining flange (46) and a fastening flange (64) for fastening the cutting blade (30) held on the retaining flange (46); wherein the retaining flange (46) includes a hub section (48) designed to be inserted through a central opening (30a) of the cutting blade (30), a flange section (50) formed integrally with the outer circumference of the hub section (48) for holding a side surface of the cutting blade (30) and a cylindrical section (53) for engaging with the front end section of the spindle (28); wherein the flange section (50) of the retaining flange (46) is formed with an intake opening (60) which opens towards the mounting flange (64), and the cylindrical section (53) of the retaining flange (46) is formed with a connecting opening (56) which is connected to the intake opening (60); wherein the connecting opening (56) is connected to a vacuum source (74) by means of a rotary connection (36) attached to the spindle housing (27), such that the connection between the connecting opening (56) and the vacuum source (74) is selectively established by an on / off valve (72), whereby, when the on / off valve (72) is opened to establish the connection between the connecting opening (56) and the vacuum source (74), a reduced pressure is applied between the retaining flange (46) and the mounting flange (64) in order to draw the mounting flange (64) towards the retaining flange (46), so that the cutting blade (30) is secured between the retaining flange (46) and the mounting flange (64); wherein a rotation restriction section (48, 52) is formed on the outer circumference of the hub section (48) of the retaining flange (46) and on the inner surface of an engagement opening (65) of the mounting flange (64) for engagement with the hub section (48) to restrict a relative rotation of the retaining flange (46) and the mounting flange (64). [2] Cutting device (2) according to claim 1, further comprising: a pressure gauge (76) provided between the rotary joint (36) and the vacuum source (74) for measuring the reduced pressure; and a safety unit for issuing a hazard signal when the reduced pressure measured by the pressure gauge (76) becomes greater than a predetermined value.

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