JP6345044B2 - Wire electrical discharge machine - Google Patents

Description

  The present invention relates to a wire electric discharge machining apparatus for cutting a wafer from an ingot using an electric discharge machining wire.

  When a wafer is cut out from an ingot made of a semiconductor material such as SiC, a processing device called a wire saw is generally used. In this wire saw, a thin wafer is cut out by cutting a wire wound around a plurality of guide rollers into an ingot while feeding the wire in the longitudinal direction.

  However, this wire saw must be continuously supplied with a slurry in which abrasive grains for processing are dispersed with respect to the wire wound around the guide roller, so that the handling thereof is complicated. In addition, since the wire comes into direct contact with the ingot, there is a high possibility that the wire is cut during processing.

  In response to these problems, a wire electric discharge machining apparatus that cuts out a wafer by using electric discharge between a wire and an ingot has been proposed (for example, refer to Patent Documents 1 and 2). This wire electric discharge machining apparatus cuts the wafer in a non-contact manner using heat generated by electric discharge, so that the mechanical load on the ingot and the wire can be reduced, and the front and back surfaces of the wafer are scratched by the abrasive grains. No worries.

JP 2000-94221 A JP 2012-240128 A

  By the way, in the wire electric discharge machining apparatus described above, machining scraps may remain in the gap between the ingot and the wire. In this case, unnecessary electric discharge is likely to occur through the accumulated debris, which causes problems such as a decrease in processing accuracy and cutting of the wire by heat.

  On the other hand, a method of immersing an ingot and a wire in a processing liquid such as pure water, a method of injecting a processing liquid into a groove of an ingot formed by processing, and the like have been studied. However, for example, when the diameter of the groove is reduced in order to increase the diameter of the wafer or to reduce the loss of cutting, the above method cannot always sufficiently remove the debris.

  This invention is made | formed in view of this problem, The place made into the objective is providing the wire electric discharge machining apparatus which can prevent that processing waste accumulates in the clearance gap between an ingot and a wire.

  According to the present invention, a wire that is wound around a plurality of guide rollers arranged at intervals and travels as the guide roller rotates, and a base that fixes the ingot so that the wire is cut into the ingot. Driving means for moving and moving the base part and the wire relatively, an ingot fixed to the base part, a high-frequency pulse power supply unit for supplying high-frequency pulse power to the wire, an ingot and the wire And a scrap removing means for preventing the processing scrap from staying between the grooves, and the scrap removing means is a groove formed in the ingot by feeding it while supplying high frequency pulse power to the ingot and the wire. And a supply promoting means for promoting the supply of the machining liquid into the groove, and the supply promoting means follows the wire during machining feed. Penetrate the groove as the wire electrical discharge machining apparatus, characterized in that the cleaning wire travel together with the wire is provided in the groove.

  In the present invention, the processing liquid supply means is a processing tank that immerses the ingot and the wire in the processing liquid, or a nozzle that sprays the processing liquid toward the ingot and supplies the processing liquid along the wire. It is preferable.

  Moreover, in this invention, it is preferable that this cleaning wire has an unevenness | corrugation in a surrounding surface.

  Moreover, in this invention, it is preferable to provide the advancing / retreating means which advances / retreats this cleaning wire along the direction of a process feed.

  Further, in the present invention, by winding the wire a plurality of times at intervals in the axial direction of the guide roller, a plurality of parallel cut portions are formed, and the plurality of cut portions are cut into the ingot. Processing feed is preferable.

  The wire electric discharge machining apparatus according to the present invention, as a supply promoting means for promoting the supply of the machining fluid to the groove formed in the ingot, enters the groove so as to follow the wire during machining feeding, Since the cleaning wire that runs along with the wire is provided, it is possible to sufficiently distribute the machining liquid into the groove and prevent the machining waste from remaining in the gap between the ingot and the wire.

It is a partial cross section side view showing typically an example of composition of a wire electric discharge machine. It is the partial cross section side view which looked at a mode that an ingot was processed from the height direction of an ingot. 3A is a partial cross-sectional side view of an ingot being processed as viewed from the longitudinal direction of the wire, and FIG. 3B is an enlarged view of a part of FIG. 3A. is there. FIG. 4A is a side view schematically showing a first example of the cleaning wire, and FIG. 4B is a side view schematically showing a second example of the cleaning wire, and FIG. ) Is a cross-sectional view schematically showing a third example of the cleaning wire.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a partial cross-sectional side view schematically showing a configuration example of a wire electric discharge machining apparatus. As shown in FIG. 1, the wire electric discharge machining apparatus 2 according to the present embodiment includes a columnar feeding roller 8 that supports a feeding bobbin 6 around which a wire 4 is wound.

  A take-up roller 12 that supports the take-up bobbin 10 is disposed at a predetermined position away from the feed roller 8 in the horizontal direction. The wire 4 fed out from the feeding bobbin 6 is wound up by the winding bobbin 10 after being used for electric discharge machining. The wire 4 is configured based on, for example, a piano wire and has conductivity necessary for electric discharge machining of the ingot 11.

  A columnar first guide roller 14 for guiding the wire 4 is disposed in the vicinity of the feeding roller 8. The wire 4 fed out from the feeding bobbin 6 is wound around the first guide roller 14 and guided in the horizontal direction.

  On the other hand, in the vicinity of the winding roller 12, a cylindrical second guide roller 16 that further guides the wire 4 guided by the first guide roller 14 is arranged. The wire 4 guided by the first guide roller 14 is wound around the second guide roller 16 and guided downward.

  A cylindrical third guide roller 18 that further guides the wire 4 guided by the second guide roller 16 is disposed below the second guide roller 16. The wire 4 guided by the second guide roller 16 is wound around the third guide roller 18 and guided in the horizontal direction. A portion of the wire 4 guided in the horizontal direction constitutes a processing portion 4a for processing the ingot 11.

  A columnar fourth guide roller 20 that further guides the wire 4 guided by the third guide roller 18 is disposed below the first guide roller 14. The wire 4 guided by the third guide roller 18 is wound around the fourth guide roller 20 and guided upward.

  The wire 4 guided by the fourth guide roller 20 is again wound around the first guide roller 14 and guided to the second guide roller 16. As described above, since the wire 4 is already wound around the first guide roller 14, the wire 4 is wound around another position here. Specifically, the wire 4 is wound around the already wound wire 4 at a predetermined interval in the axial direction of the first guide roller 14.

  Similarly, the wire 4 guided by the first guide roller 14 is again wound around the second guide roller 16 and guided to the third guide roller 18. The wire 4 guided by the second guide roller 16 is again wound around the third guide roller 18 and guided to the fourth guide roller 20. Further, the wire 4 guided by the third guide roller 18 is again wound around the fourth guide roller 20 and guided to the first guide roller 14.

  As described above, since the wire 4 is already wound around the second guide roller 16, the third guide roller 18, and the fourth guide roller 20, the wire 4 is wound around another position here. Specifically, the wire 4 is wound around the already wound wire 4 at a predetermined interval in the axial direction of the second guide roller 16, the third guide roller 18, or the fourth guide roller 20. It is hung.

  The wire 4 guided by the fourth guide roller 20 is further wound around the first guide roller 14 and guided to the second guide roller 16. Also here, the wire 4 is wound around the axial direction of the first guide roller 14 with a predetermined interval.

  Thus, the wire 4 is wound around the first guide roller 14, the second guide roller 16, the third guide roller 18, and the fourth guide roller 20 a plurality of times at predetermined intervals in the axial direction. The number of times the wire 4 is wound is arbitrarily set according to the processing conditions and the like. After winding the wire 4 until the preset number of times is reached, the wire 4 is fixed to the winding bobbin 10 via the second guide roller 16.

  Thereby, a plurality of processing parts 4a are arranged in parallel between the third guide roller 18 and the fourth guide roller 20, and a plurality of wafers can be cut out from the ingot 11 at a time. The interval in the axial direction of the wire 4 wound around the third guide roller 18 and the fourth guide roller 20 (that is, the interval between the processed portions 4a) corresponds to the thickness of the wafer to be cut out, and is 1 mm, for example. However, the interval in the axial direction of the wire 4 (the interval between the processed portions 4a) is not limited to this.

  Further, a rotation drive source (not shown) such as a motor is connected to the feed roller 8, the take-up roller 12, and each guide roller. If the feed roller 8, the take-up roller 12, and each guide roller are rotated by this rotational drive source, the wire 4 is fed with a predetermined wire as the feed roller 8, the take-up roller 12 and each guide roller are rotated. Sent in the direction (runs). The rotation amounts of the third guide roller 18 and the fourth guide roller 20 are controlled so that a predetermined tension is applied to the processed portion 4a of the wire 4.

  A base (base part) 22 that supports the ingot 11 is disposed above the processing part 4a. The base 22 is made of, for example, a conductive material such as carbon, and the ingot 11 is fixed to the lower surface side via a conductive adhesive 24.

  The ingot 11 is formed in a cylindrical shape with a material such as SiC or diamond (single crystal diamond), for example, and is a base so that the height direction (crystal growth direction) of the ingot 11 is orthogonal to the wire feed direction. 22 is fixed.

  The base 22 is moved in the vertical direction (machining feed direction) perpendicular to the height direction of the ingot 11 by a drive unit (drive means) 26 disposed above. Thereby, the base 22 and the wire 4 can be relatively moved (processed feed) so that the wire 4 (processed portion 4a) is cut into the ingot 11.

  A high frequency pulse power supply (high frequency pulse power supply unit) 28 for supplying high frequency pulse power for electric discharge machining is connected to the base 22. The high-frequency pulse power supply 28 supplies a first high-frequency pulse power to the ingot 11 via the base 22 and the conductive adhesive 24.

  On the other hand, between the 1st guide roller 14 and the 4th guide roller 20, and between the 2nd guide roller 16 and the 3rd guide roller 18, it is each connected to the high frequency pulse power supply 28, and is the electric power feeding which contacts the wire 4 Terminals 30 and 32 are disposed. The high-frequency pulse power supply 28 supplies a second high-frequency pulse power having a polarity different from that of the first high-frequency pulse power to the wire 4 via the terminals 30 and 32.

  At a position surrounding the third guide roller 18 and the fourth guide roller 20, a processing tank (processing liquid supply means, debris removal means) 34 is disposed. A processing liquid 36 such as pure water is stored inside the processing tank 34, and at least a part of the processing portion 4 a of the wire 4 and a part of the ingot 11 are immersed in the processing liquid 36.

  Further, a pair of nozzles (working fluid supply means and debris removal means) 38 and 40 for injecting the working liquid 36 toward the ingot 11 are arranged in the vicinity of the processing portion 4 a so as to sandwich the ingot 11. The nozzles 38 and 40 supply the machining liquid 36 to the ingot 11 along the machining portion 4 a of the wire 4.

  A cleaning wire (supply promoting means, debris removing means) 42 is disposed below each of the plurality of processed portions 4a. The cleaning wire 42 is wound around a cylindrical first cleaning guide roller 44 disposed in the vicinity of the fourth guide roller 20 and a cylindrical second cleaning guide roller 46 disposed in the vicinity of the third guide roller 18. It is hung.

  A rotation drive source (not shown) such as a motor is connected to the first cleaning guide roller 44 and the second cleaning guide roller 46. If the first cleaning guide roller 44 and the second cleaning guide roller 46 are rotated by this rotational drive source, the cleaning wire 42 is moved in a predetermined cleaning wire feeding direction so as to run in parallel with the wire 4 (processing portion 4a). Can send.

  The first cleaning guide roller 44 and the second cleaning guide roller 46 are supported by moving units (advance / retreat means) 48 and 50, respectively. The moving units 48 and 50 move (advance and retract) the first cleaning guide roller 44 and the second cleaning guide roller 46 in the vertical direction (processing feed direction). That is, the cleaning wire 42 can be moved in the vertical direction.

  Next, the electric discharge machining method of the ingot 11 using the wire electric discharge machining apparatus 2 mentioned above is demonstrated. FIG. 2 is a partial cross-sectional side view schematically showing how the ingot 11 is subjected to electric discharge machining, and FIG. 3A is a partial cross-sectional side view schematically showing how the ingot 11 is electric discharge machined. FIG. 3B is an enlarged view of a part of FIG.

  In the processing method of this embodiment, first, the first high-frequency pulse power is supplied from the high-frequency pulse power supply 28 to the ingot 11, and the second high-frequency pulse power having a polarity different from that of the first high-frequency pulse power is supplied to the wire 4. . Further, each guide roller is rotated to feed the wire 4 in a predetermined wire feeding direction as shown in FIG.

  Further, the ingot 11 is moved downward (processed feed) by the drive unit 26 so that the wire 4 (processed portion 4a) is cut into the ingot 11. As a result, when the ingot 11 that is in an insulating state in the machining liquid 36 and the processed portion 4a of the wire 4 sufficiently approach each other, the insulation is broken and a discharge occurs between the ingot 11 and the processed portion 4a.

  As a result, the ingot 11 is melted by the heat generated by the discharge. Further, the temperature of the machining liquid 36 rises rapidly and boils, the volume expands and the molten portion of the ingot 11 is scattered. In this way, by moving the ingot 11 downward while supplying high-frequency pulse power to the ingot 11 and the wire 4, as shown in FIG. 3A, the groove 11a corresponding to the movement path of the processed portion 4a is ingot. 11 can be formed.

  The downward movement of the ingot 11 is continued until the processed portion 4 a of the wire 4 is slightly cut into the base 22. Thereby, the ingot 11 can be cut and a plurality of wafers can be cut out.

  As described above, the processing portion 4a of the wire 4 and a part of the ingot 11 are immersed in the processing fluid 36, and the processing fluid 36 is ejected from the pair of nozzles 38 and 40 along the processing portion 4a of the wire 4. Is done. Therefore, as shown in FIG. 3 (B), most of the scrap (work scrap) 11b generated by the processing is removed without staying.

  However, a part of the scrap 11 b may stay between the ingot 11 and the processed portion 4 a of the wire 4. In particular, when the diameter of the ingot 11 (wafer) is increased or the width of the groove 11a is reduced in order to reduce the loss of cutting, the retention of the waste 11b becomes more remarkable.

  Therefore, in the present embodiment, a cleaning wire 42 that is sent so as to run in parallel with the wire 4 is disposed below each processed portion 4a. Accordingly, when the ingot 11 is moved downward to form the groove 11a, the cleaning wire 42 enters the groove 11a so as to follow the processed portion 4a of the wire 4, and the flow of the machining liquid 36 is formed in the groove 11a. Is done. That is, the supply of the machining liquid 36 into the groove 11a is promoted.

  As a result, it is possible to prevent the processing waste 11b from staying between the ingot 11 and the processing portion 4a of the wire 4. The cleaning wire 42 is preferably moved up and down by the moving units 48 and 50.

  Thereby, supply of the process liquid 36 in the groove | channel 11a is further accelerated | stimulated, and the residence of the waste 11b can be prevented more appropriately. The peristaltic movement of the cleaning wire 42 may be performed, for example, while keeping the cleaning wire 42 and the processing portion 4a parallel, or may be performed such that the cleaning wire 42 is inclined with respect to the processing portion 4a.

  The shape and the like of the cleaning wire 42 can be arbitrarily selected and changed. 4A is a side view schematically showing a first example of the cleaning wire 42, and FIG. 4B is a side view schematically showing a second example of the cleaning wire 42. FIG. 6C is a cross-sectional view schematically showing a third example of the cleaning wire 42.

  The cleaning wire 42a according to the first example is a general wire such as a piano wire. The cleaning wire 42b according to the second example is formed by twisting a plurality of wires, for example, and has an uneven surface. The cleaning wire 42c according to the third example is formed, for example, by subjecting a peripheral surface of a general wire to uneven processing.

  In order to increase the flow of the machining liquid 36 formed in the groove 11a, a cleaning wire 42 having irregularities on the peripheral surface, such as the cleaning wire 42b according to the second example and the cleaning wire 42c according to the third example, is used. Use it.

  As described above, the wire electric discharge machining apparatus 2 according to the present embodiment moves the ingot 11 downward as machining supply means for promoting the supply of the machining liquid 36 to the groove 11a formed in the ingot 11 (machining feed). In this case, the cleaning wire 42 that enters the groove 11a so as to follow the wire 4 and is fed so as to run along with the wire 4 in the groove 11a is provided, so that the machining liquid 36 is sufficiently distributed into the groove 11a. Further, it is possible to prevent the processing waste 11b from staying in the gap between the ingot 11 and the wire 4.

  In addition, this invention is not limited to description of the said embodiment, A various change can be implemented. For example, in the above-described embodiment, the wire 4 is wound around each guide roller a plurality of times to configure a plurality of processing portions 4a arranged in parallel, but the number of the processing portions 4a may be one.

  In addition, the configurations, methods, and the like according to the above-described embodiments can be appropriately modified and implemented without departing from the scope of the object of the present invention.

DESCRIPTION OF SYMBOLS 2 Wire electrical discharge machining apparatus 4 Wire 4a Processing part 6 Feeding bobbin 8 Feeding roller 10 Winding bobbin 12 Winding roller 14 1st guide roller 16 2nd guide roller 18 3rd guide roller 20 4th guide roller 22 Base (base) Part)
24 conductive adhesive 26 drive unit (drive means)
28 High-frequency pulse power supply (high-frequency pulse power supply unit)
30, 32 Terminal 34 Processing tank (working fluid supply means, debris removal means)
36 machining fluid 38, 40 nozzle (machining fluid supply means, debris removal means)
42, 42a, 42b, 42c Cleaning wire (supply promoting means, debris removing means)
44 First cleaning guide roller 46 Second cleaning guide roller 48, 50 Moving unit (advance / retreat means)
11 Ingot 11a Groove 11b Scrap (Processed Scrap)

Claims (5)

A wire that is wound around a plurality of guide rollers arranged at intervals, and travels as the guide rollers rotate,
A driving means for moving and processing the base part for fixing the ingot and the wire relatively so as to cut the wire into the ingot;
A high-frequency pulse power supply unit that supplies high-frequency pulse power to the ingot fixed to the base and the wire;
A scrap removing means for preventing machining waste from staying between the ingot and the wire,
The debris removing means includes
A machining fluid supply means for supplying a machining fluid to a groove formed in the ingot by feeding while feeding high frequency pulse power to the ingot and the wire;
Supply facilitating means for facilitating the supply of the working fluid into the groove,
The supply promoting means is
A wire electric discharge machining apparatus, which is a cleaning wire that penetrates into the groove so as to follow the wire at the time of machining feeding and runs alongside the wire in the groove.   The processing liquid supply means is a processing tank that immerses the ingot and the wire in the processing liquid, or a nozzle that jets the processing liquid toward the ingot and supplies the processing liquid along the wire. The wire electric discharge machining apparatus according to claim 1.   The wire electric discharge machining apparatus according to claim 1, wherein the cleaning wire has irregularities on a peripheral surface thereof.   The wire electric discharge machining apparatus according to any one of claims 1 to 3, further comprising advance / retreat means for advancing / retreating the cleaning wire along a machining feed direction. By winding the wire a plurality of times at intervals in the axial direction of the guide roller, a plurality of parallel cutting portions are formed,
The wire electric discharge machining apparatus according to any one of claims 1 to 4, wherein the plurality of cutting portions are processed and fed so as to be cut into an ingot.