JP2009160671A - Spindle assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent oscillation generated by rotation from propagating to the outside of a spindle assembly. <P>SOLUTION: The spindle assembly is provided with: a spindle housing 32 having a first air feeding passage; a second air feeding passage; a spindle inserting hole 82 formed in the center; and a plurality of branch passages 98 feeding compressed air from the second air feeding passage to the spindle inserting hole, and also has: a bearing shaft 80 inserted into the spindle housing; a spindle 26 inserted into the spindle inserting hole of the bearing shaft; a radial air bearing 102 formed between the spindle and an inner wall defining the spindle inserting hole of the bearing shaft; and a compressed air feeding source 84 feeding the compressed air to a gap between the spindle housing and the bearing shaft through the first air feeding passage, and also to the radial air bearing. The bearing shaft is held by the compressed air jetted from the first air feeding passage in a radial direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spindle assembly on which a processing tool such as a cutting blade or a grinding wheel is mounted.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. The line to be divided is cut by a cutting device and divided into individual devices, which are used for electric devices such as mobile phones and personal computers.

  A cutting apparatus (dicing apparatus) that divides a wafer into individual devices includes a chuck table that holds a wafer, and a cutting means that rotatably supports a cutting blade that cuts a division line of the wafer held on the chuck table. A compressed air supply source that supplies compressed air to an air bearing that rotatably supports the spindle of the cutting means is provided, and the wafer can be divided into individual devices with high accuracy.

  An air bearing that rotatably supports a spindle of a cutting device is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-208474 and Japanese Patent Application Laid-Open No. 11-117939. Yes.

In the air bearing disclosed in Japanese Patent Application Laid-Open No. 11-117939, a radial bearing portion made of an air bearing is provided on the outer peripheral surface of a draft plate integrally formed with the spindle, thereby increasing the rigidity in the radial direction. Prevents minute shakes.
JP-A-7-208474 JP-A-11-117939

  In a spindle assembly that supports a spindle in a radial direction by compressed air, radial vibration is generated as the spindle rotates. When the spindle assembly is incorporated in the machine tool as described above, vibration generated from the spindle propagates to the entire apparatus and affects the processing quality and processing accuracy.

  In particular, in a cutting machine or grinding / polishing machine in which the spindle is directly connected to the machining point, the deterioration of the machining quality due to the vibration of the spindle appears remarkably, and the generated vibration becomes larger as the spindle rotates at a higher speed, resulting in worsening of the machining quality. , Leading to deterioration of processing accuracy.

  Specifically, in the cutting device, an increase in the cutting depth variation, an increase in chipping called chipping generated at the edge of the processing groove, a cutting feed position control failure due to a scale reading failure, and the like occur. In addition, in the grinding / polishing apparatus, there are variations in the finish thickness over a wide range called “surface burn” or “waviness” that burns the processed surface of the workpiece.

  The present invention has been made in view of these points, and an object of the present invention is to provide a spindle assembly in which vibration generated by rotation is not propagated outside the spindle assembly.

  According to the first aspect of the present invention, the spindle assembly includes a spindle housing having a first air supply path, a second air supply path, a spindle insertion hole formed in the center, and the second air. A plurality of branch passages for supplying compressed air from a supply passage to the spindle insertion hole, a bearing shaft inserted into the spindle housing, and a spindle inserted into the spindle insertion hole of the bearing shaft; A radial air bearing formed between the spindle and an inner wall defining a spindle insertion hole of the bearing shaft, and a gap between the spindle housing and the bearing shaft via the first air supply path The compressed air is supplied and the radial air bearing is connected via the second air supply path and the branch path. A spindle assembly, wherein the bearing shaft is held by compressed air ejected in a radial direction from the first air supply path. .

  According to the second aspect of the present invention, the spindle assembly is formed at the center of the spindle housing having the first air supply path, the second air supply path communicating with the outer peripheral surface and extending in the axial direction. A spindle insertion hole, and a plurality of branch paths for supplying compressed air from the second air supply path to the spindle insertion hole, and a bearing shaft inserted into the spindle housing; A spindle inserted into a spindle insertion hole; a radial air bearing formed between the spindle and an inner wall defining a spindle insertion hole of the bearing shaft; and the spindle housing via the first air supply And a compressed air supply source for supplying compressed air to the gap between the bearing shaft and the bearing shaft. The supplied compressed air is supplied to the radial air bearing through the second air supply path and the branch path, and the bearing shaft is compressed by the compressed air ejected in the radial direction from the first air supply path. A spindle assembly is provided that is retained.

  According to the present invention, vibration caused by rotation can be suppressed by the air layer between the spindle housing and the bearing shaft, and vibration is not propagated outside the spindle assembly. Therefore, when the spindle assembly of the present invention is incorporated in a processing apparatus and used, vibrations are not propagated to the processing apparatus and high-precision processing is possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an appearance of a cutting apparatus 2 having a spindle assembly according to an embodiment of the present invention, which can divide a semiconductor wafer into individual chips (devices).

  On the front side of the cutting device 2, there is provided operating means 4 for an operator to input instructions to the device such as machining conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  As shown in FIG. 2, on the surface of the wafer W to be diced, the first street S1 and the second street S2 are formed orthogonally, and the first street S1 and the second street S2 A plurality of devices D are partitioned and formed on the wafer W.

  The wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral edge of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the frame F via the dicing tape T, and a plurality of wafers (for example, 25 sheets) are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8, a loading / unloading means 10 for unloading the wafer W before cutting from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8 is disposed. Between the wafer cassette 8 and the loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. Positioning means 14 for positioning at a certain position is provided.

  In the vicinity of the temporary placement area 12, transport means 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed, and the wafer W carried to the temporary placement area 12 is It is attracted by the transport means 16 and transported onto the chuck table 18 and is sucked by the chuck table 18, and is held on the chuck table 18 by fixing the frame F by a plurality of fixing means 19.

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction. Above the movement path of the chuck table 18 in the X-axis direction, an alignment unit 20 that detects a street to be cut of the wafer W is provided. It is arranged.

  The alignment unit 20 includes an imaging unit 22 that images the surface of the wafer W, and can detect a street to be cut by a process such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display unit 6.

  On the left side of the alignment means 20, a cutting means 24 for cutting the wafer W held on the chuck table 18 is disposed. The cutting means 24 is configured integrally with the alignment means 20, and both move together in the Y-axis direction and the Z-axis direction.

  The cutting means 24 is configured by attaching a cutting blade 28 to the tip of a rotatable spindle 26 and is movable in the Y-axis direction and the Z-axis direction. The cutting blade 28 is located on the extended line of the imaging means 22 in the X-axis direction.

  Referring to FIG. 3, an exploded perspective view showing the relationship between the spindle and the blade mount attached to the spindle is shown. A spindle 26 that is rotationally driven by a servo motor or a synchronous motor (not shown) is rotatably accommodated in a spindle housing 32 of the spindle assembly 30. The spindle 26 has a tapered portion 26a and a tip small diameter portion 26b, and a male screw 34 is formed on the tip small diameter portion 26b.

  A blade mount 36 includes a boss part (convex part) 38 and a fixed flange 40 formed integrally with the boss part 38, and a male screw 42 is formed on the boss part 38. Further, the blade mount 36 has a mounting hole 43.

  In the blade mount 36, the mounting hole 43 is inserted into the tip small diameter portion 26b and the tapered portion 26a of the spindle 26, and the nut 44 is screwed into the male screw 34 and tightened, so that the tip end portion of the spindle 26 as shown in FIG. Attached to.

  FIG. 4 is an exploded perspective view showing the mounting relationship between the spindle 26 to which the blade mount 36 is fixed and the cutting blade 28. The cutting blade 28 is called a hub blade, and is configured by electrodepositing a cutting blade 50 in which diamond abrasive grains are dispersed in a nickel base material on the outer periphery of a circular base 46 having a circular hub 48.

  The cutting blade 28 is attached to the spindle 26 by inserting the mounting hole 52 of the cutting blade 28 into the boss 38 of the blade mount 36 and screwing the fixing nut 54 into the male screw 42 of the boss 38.

  Referring to FIG. 5, an enlarged perspective view of the cutting means 24 is shown. A blade cover 60 covers the cutting blade 28, and a cutting water nozzle (not shown) that extends along the side surface of the cutting blade 28 is attached to the blade cover 60. Cutting water is supplied to a cutting water nozzle (not shown) via the pipe 72.

  Reference numeral 62 denotes a detachable cover, which is attached to the blade cover 60 with screws 64. The detachable cover 62 has a cutting water nozzle 70 that extends along the side surface of the cutting blade 28 when attached to the blade cover 60. The cutting water is supplied to the cutting water nozzle 70 via the pipe 74.

  A blade detection block 66 is attached to the blade cover 60 with screws 68. A blade sensor (not shown) composed of a light emitting element and a light receiving element is attached to the blade detection block 66, and the state of the cutting blade 50 of the cutting blade 28 is detected by this blade sensor.

  When the cutting of the cutting edge 50 is detected by the blade sensor, the cutting blade 28 is replaced with a new cutting blade. Reference numeral 76 denotes an adjusting screw for adjusting the position of the blade sensor.

  Next, the spindle assembly 30 according to the first embodiment of the present invention will be described in detail with reference to FIG. A bearing shaft 80 is inserted into the spindle housing 32 with a very small gap.

  The bearing shaft 80 has a spindle insertion hole 82 at the center thereof, and the spindle 26 is inserted into the spindle insertion hole 82. The spindle housing 32 is formed with a plurality of air supply paths 88 that are spaced apart at equal intervals in the circumferential direction and extend in the axial direction.

  Compressed air from a compressed air supply source 84 is supplied to these air supply paths 88 through an air supply port 86. The air supply port for supplying the compressed air to the air supply path 88 may be formed at the right end portion of the spindle housing 32. The compressed air supplied to the air supply path 88 is introduced into a gap 92 between the spindle housing 32 and the bearing shaft 80 via a plurality of radial direction supply paths 90.

  On the other hand, compressed air from the compressed air supply source 84 is supplied to the air supply path 94 of the bearing shaft 80 through an air supply port formed at the right end portion (not shown) of the bearing shaft 80.

  Each of the bearing shafts 80 communicates with the air supply path 94 and is provided with a plurality of annular supply paths 96 that are axially spaced from each other. The bearing shaft 80 extends radially inward from each annular supply path 96 to supply compressed air to the spindle insertion hole 82. A plurality of branch paths 98 are formed. In each branch 98, an orifice 100 having a predetermined opening diameter is inserted.

  In a state where compressed air is not supplied into the spindle insertion hole 82, there is nothing to support the spindle 26, so the spindle 26 is in contact with the bottom wall defining the spindle insertion hole 82 of the bearing shaft 80.

  In a state where compressed air is not supplied to the gap 92 between the spindle housing 32 and the bearing shaft 80, there is nothing to support the bearing shaft 80, so the bearing shaft 80 is in contact with the bottom of the inner wall of the spindle housing 32. .

  When compressed air is supplied into the spindle insertion hole 82 from the compressed air supply source 84 through the air supply path 94, the annular supply path 96, the branch path 98, and the orifice 100, the spindle 26 is supported by the compressed air and is shown in FIG. The radial air bearing 102 is formed between the spindle 26 and the inner wall of the bearing shaft 80 that defines the spindle insertion hole 82 of the bearing shaft 80.

  On the other hand, when compressed air from the compressed air supply source 84 is supplied to the gap 92 between the spindle housing 32 and the bearing shaft 80 via the air supply port 86, the air supply path 88, and the radial direction air supply path 90, The bearing shaft 80 floats as shown in FIG. 6 and supports the bearing shaft 80 with the compressed air supplied into the gap 92.

  Thus, in the state shown in FIG. 6 in which compressed air is introduced into the radial air bearing 102 and the clearance 92 between the spindle housing 32 and the bearing shaft 80, the spindle 26 is rotated at a high speed by a servo motor or a synchronous motor (not shown). (60000-90000 rpm), vibration in the radial direction is generated in the spindle 26 due to the subsidence due to the weight of the spindle 26 and the difference in air density generated in the radial air bearing 102 as the spindle 26 rotates at high speed.

  This vibration is transmitted to the bearing shaft 80, and the bearing shaft 80 also vibrates in the radial direction. However, since the compressed air is supplied to the gap 92 between the spindle housing 32 and the bearing shaft 80 and the bearing shaft 80 is supported by the compressed air, the radial vibration of the bearing shaft 80 is compressed in the gap 92. Absorption by air and transmission of vibration to the spindle housing 32 are suppressed. Therefore, it is possible to process the wafer W with high accuracy by the cutting blade 28.

  Next, a spindle assembly 30A according to a second embodiment of the present invention will be described with reference to FIG. In the description of the present embodiment, components that are substantially the same as those of the first embodiment shown in FIG.

  A bearing shaft 80 is inserted into the spindle housing 32 with a very small gap. The bearing shaft 80 has a spindle insertion hole 82 at the center thereof, and the spindle 26 is inserted into the spindle insertion hole 82.

  The spindle housing 32 is formed with a plurality of air supply paths 88 that are spaced apart at equal intervals in the circumferential direction and extend in the axial direction. One air supply path 88 is connected to a compressed air supply source 84, and compressed air is directly supplied thereto. The other air supply path 88 is supplied with compressed air via an annular supply path 95.

  The compressed air supplied to each air supply path 88 is introduced into a gap 92 between the spindle housing 32 and the bearing shaft 80 via a plurality of radial direction supply paths 90.

  On the other hand, the bearing shaft 80 has an air supply path 106 that extends in the axial direction, and an air introduction port 104 that communicates the air supply path 106 with the outer peripheral surface. Each of the bearing shafts 80 further communicates with the air supply path 106 and is spaced apart in the axial direction from a plurality of annular supply paths 96, extending radially inward from each of the annular supply paths 96, and supplying compressed air to the spindle insertion hole 82. A plurality of branch paths 98 to be supplied are formed. In each branch 98, an orifice 100 having a predetermined opening diameter is inserted.

  As in the first embodiment, since there is nothing to support the spindle 26 when compressed air is not supplied into the spindle insertion hole 82, the spindle 26 contacts the bottom wall that defines the spindle insertion hole 82 of the bearing shaft 80. is doing.

  Further, in a state where the compressed air is not supplied to the gap 92 between the spindle housing 32 and the bearing shaft 80, there is nothing to support the bearing shaft 80, so the bearing shaft 80 is in contact with the bottom of the inner wall of the spindle housing 32. .

  When compressed air is supplied from the compressed air supply source 84 to the gap 92 between the spindle housing 32 and the bearing shaft 80 via the air supply path 88 and the radial air supply path 90, the bearing shaft 80 is shown in FIG. The bearing shaft 80 is supported by the compressed air supplied into the gap 92.

  Further, since the gap 92 communicates with the air inlet 104 of the bearing shaft 80, the compressed air passes through the air inlet 104, the air supply path 106, the annular air supply path 96, the branch path 98 and the orifice 100 from the gap 92. Are supplied into the spindle insertion hole 82.

  As a result, the spindle 26 floats while being supported by compressed air as shown in FIG. 7, and a radial air bearing 102 is formed between the spindle 26 and the inner wall defining the spindle insertion hole 82 of the bearing shaft 80. .

  As in the first embodiment shown in FIG. 6, in the state shown in FIG. 7 in which compressed air is introduced into the radial air bearing 102 and the gap 92 between the spindle housing 32 and the bearing shaft 80, a servo motor (not shown) or When the spindle 26 is rotated at a high speed (60,000 to 90000 rpm) by a synchronous motor or the like, the spindle 26 is caused by the difference in the air density generated in the radial air bearing 102 as the spindle 26 sinks due to its own weight and the spindle 26 rotates at a high speed. Radial vibration occurs.

  This vibration is transmitted to the bearing shaft 80, and the bearing shaft 80 also vibrates in the radial direction. However, since the compressed air is supplied to the gap 92 between the spindle housing 32 and the bearing shaft 80 and the bearing shaft 80 is supported by the compressed air, the vibration in the radial direction of the bearing shaft 80 is compressed in the gap 92. Absorption by air and transmission of vibration to the spindle housing 32 are suppressed. Therefore, it is possible to process the wafer W with high accuracy by the cutting blade 28.

  Referring to FIG. 8, an external perspective view of the grinding device 130 is shown. Reference numeral 132 denotes a grinding unit. The grinding unit 132 is attached to a moving base 154 that moves up and down along a pair of guide rails 150 and 152 via a support portion 134.

  The grinding unit 132 includes a spindle housing 136 attached to the support portion 134, a spindle 138 rotatably accommodated in the spindle housing 136, and a servo motor that rotationally drives the spindle 138. The spindle 138 is rotatably supported in the spindle housing 136 by an air bearing.

  As shown in FIG. 9A, a mount 140 is integrally formed at the tip of the spindle 138, and a grinding wheel 142 is screwed to the mount 140 as shown in FIG. 9B.

  The grinding wheel 142 is configured by, for example, a plurality of grinding wheels 146 in which diamond abrasive grains having a particle diameter of 0.3 to 1.0 μm are hardened with vitrified bonds are fixed to a free end portion of a wheel base 144.

  Thus, the present invention is also applicable to the grinding device 130 having a vertical spindle supported by an air bearing. By supporting the spindle 138 of the grinding apparatus with a radial air bearing and supporting the bearing shaft with compressed air, transmission of vibration in the radial direction to the spindle housing 136 is suppressed.

It is an external appearance perspective view of the cutting device suitable for applying this invention. It is a perspective view which shows the wafer integrated with the flame | frame. It is a disassembled perspective view which shows the relationship between a spindle assembly and the blade mount which should be fixed to a spindle. It is a disassembled perspective view which shows the relationship between a spindle assembly and the hub blade which should be mounted | worn with a spindle. It is an expansion perspective view of a cutting means. It is a longitudinal cross-sectional view of 1st Embodiment of this invention. It is a longitudinal cross-sectional view of 2nd Embodiment of this invention. It is an external appearance perspective view of a grinding device. FIG. 9A is an exploded perspective view showing a relationship between a spindle mount and a grinding wheel screwed to the mount, and FIG. 9B is a perspective view showing a grinding wheel screwed to the spindle mount. .

Explanation of symbols

2 Cutting device 18 Chuck table 24 Cutting means (cutting unit)
26 Spindle 28 Cutting blade 30 Spindle assembly 32 Spindle housing 80 Bearing shaft 84 Compressed air supply source 88, 94 Air supply path 92 Clearance 96 Annular supply path 98 Branch path 100 Orifice 102 Radial air bearing

Claims (2)

A spindle assembly,
A spindle housing having a first air supply path;
A second air supply passage, a spindle insertion hole formed in the center, and a plurality of branch passages for supplying compressed air from the second air supply passage to the spindle insertion hole; Bearing shaft inserted into the
A spindle inserted into a spindle insertion hole of the bearing shaft;
A radial air bearing formed between the spindle and an inner wall defining a spindle insertion hole of the bearing shaft;
Compressed air is supplied to the gap between the spindle housing and the bearing shaft via the first air supply path, and compressed to the radial air bearing via the second air supply path and the branch path. A compressed air supply source for supplying air,
The spindle assembly, wherein the bearing shaft is held by compressed air ejected in a radial direction from the first air supply path. A spindle assembly,
A spindle housing having a first air supply path;
A second air supply path communicating with the outer peripheral surface and extending in the axial direction; a spindle insertion hole formed in the center; and a plurality of compressed air from the second air supply path for supplying compressed air to the spindle insertion hole A bearing shaft having a branch path and inserted into the spindle housing;
A spindle inserted into a spindle insertion hole of the bearing shaft;
A radial air bearing formed between the spindle and an inner wall defining a spindle insertion hole of the bearing shaft;
A compressed air supply source for supplying compressed air to a gap between the spindle housing and the bearing shaft via the first air supply;
The compressed air supplied to the gap is supplied to the radial air bearing through the second air supply path and the branch path,
The spindle assembly, wherein the bearing shaft is held by compressed air ejected in a radial direction from the first air supply path.

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