JPH10175153A - Wire saw and cutting method of work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow process cutting a wafer with the even plate thickness and of a high quality, by correcting the tendency to increase the plate thickness of the cut wafer, as making deeper the cutting depth toward the processing direction, in a wire saw. SOLUTION: A wire 15 is wound at a specific pitch between plural rollers 13 and 14 for processing, and a work 20 is contacted to the wire 15 while running the wire 15, so as to apply the cutting process to the work 20. A control device 34 in order to convert the new wire feeding amount of the wire 15 between the rollers 13 and 14 according to the cutting depth is provided. The control device 34 regulates the running speed of the wire 15, and regulates the forward and the rearward moving time ratio in the both directions running of the wire 15, so as to convert the new wire feeding amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire saw and a method for cutting a work made of a brittle material such as a semiconductor material, a magnetic material, and a ceramic using a wire.

[0002]

2. Description of the Related Art In a wire saw of this type, a plurality of processing rollers are disposed at predetermined intervals, and a large number of annular grooves are formed on the outer periphery of the rollers at a predetermined pitch. In addition, one wire is sequentially wound around the annular groove between the processing rollers. Then, running on the wire, a slurry containing loose abrasive grains is supplied on the wire,
In this state, the work is pressed against the wire and is brought into contact with the wire, so that the work is cut.

[0003]

However, in a conventional wire saw, for example, when a workpiece having a circular cross section (that is, a cylindrical workpiece) is cut into a slice, the cutting depth of the workpiece in the processing direction is reduced. As the depth increases, the sharpness of the wire slows down, as shown in FIG.
The thickness of the obtained wafer 20a tended to increase.
For this reason, it has been difficult to cut a high-quality wafer having a uniform thickness.

The present invention has been made in view of the problems existing in the prior art, and has as its object to increase the thickness of a wafer cut out as the cutting depth increases in the processing direction. It is an object of the present invention to provide a wire saw and a method for cutting a workpiece, which can correct the tendency to increase in diameter and can cut a high-quality wafer having a uniform thickness.

[0005]

In order to achieve the above object, a wire saw and a method for cutting a workpiece according to the present invention are configured as described in the claims.

In the wire saw and the work cutting method according to the first, second, fifth and sixth aspects, the work is pressed into contact with the wire while the wire is running, and the work is cut into slices. At the time of this cutting process, the amount of new wire feeding between the processing rollers is changed by the control means in accordance with the cutting depth of the work (and / or the cutting length of the work). As a result, the tendency that the thickness of the cut wafer increases as the cutting depth or the like increases in the processing direction can be effectively corrected.

In the wire saw according to the third aspect, the new line feed amount is changed by adjusting the traveling speed of the wire by the control means. For this reason, the tendency of the wafer thickness to increase can be easily corrected.

In the wire saw according to the fourth aspect, the new line feed amount is changed by adjusting the reciprocating time ratio in the bidirectional traveling of the wire by the control means. For this reason,
The tendency to increase the thickness of the wafer can be easily corrected.

According to a seventh aspect of the present invention, in the method of cutting a workpiece according to the fifth aspect, the traveling speed of the wire is increased in accordance with an increase in the depth of the workpiece. According to this method, the tendency of the sharpness of the wire due to the deeper cutting depth of the work to be increased can be compensated for by increasing the traveling speed of the wire. Is made substantially uniform. Therefore, it is possible to correct a tendency that the thickness of the cut wafer increases as the cutting depth increases in the processing direction.

[0010] In the method for cutting a workpiece according to claim 8,
8. The method according to claim 7, wherein the workpiece is fed at a constant speed to the traveling wire. One advantage of this method is that
In order to maintain the sharpness of the traveling wire, it is not necessary to intentionally reduce the work feed speed, so that the cutting time does not become long.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of a wire saw and a method for cutting a workpiece according to the present invention will be described below with reference to the drawings.

(First Embodiment) As shown in FIGS. 1 and 2, a cutting mechanism 11 is mounted on an apparatus frame 12. The cutting mechanism 11 includes a processing drive roller 13 and a processing driven roller 14 extending in parallel, and a large number of annular grooves 13a and 14a are formed at a predetermined pitch on the outer periphery thereof. In the drawings, in order to facilitate understanding,
The number of the annular grooves 13a and 14a is drawn smaller than the actual number.

A wire 15 made of one wire is continuously wound around each of the annular grooves 13a and 14a of the processing rollers 13 and 14. The wire running motor 16 is disposed on the apparatus frame 12, and the processing drive roller 13 is directly rotated by the motor 16, and the processed driven roller 14 is rotated via the running wire 15. The rotation of the processing rollers 13 and 14 causes the wire 15 to reciprocate intermittently at a predetermined traveling speed in both directions.

A work supporting mechanism 19 is supported by the frame 12 above the cutting mechanism 11 so as to be vertically movable,
A work 20 made of a brittle material is removably set below the lower part. The work 20 is, for example, cylindrical. The work lifting motor 21 is disposed on the frame 12, and the work support mechanism 19 is moved up and down by a motor 21 via a ball screw (not shown). Therefore, the work support mechanism 19 and the work lifting / lowering motor 21 constitute a work supply means or a work feed means for supplying or feeding the work 20 to the traveling wire 15.

During operation of the wire saw, the wire 15
Is reciprocally moved between the processing rollers 13 and 14 of the cutting mechanism 11 while the work supporting mechanism 19 is moved by the cutting mechanism 1.
It is lowered toward 1. At this time, a slurry containing loose abrasive particles is supplied onto the wire 15 by a slurry supply device (not shown), and the work 20
Are pressed and contacted. As a result, the work 2
0 is sliced.

A reel mechanism 22 is mounted on the frame 12, and is a feed reel 23 for feeding the wire 15.
And a take-up reel 24 for taking up the wire 15. A pair of reel rotation motors 25 and 26 composed of servo motors whose rotation direction and rotation speed can be changed are arranged on the frame 12, and reels 23 and 24 are connected to their motor shafts. The traverse mechanism 27 is mounted on the frame 12 adjacent to the reel mechanism 22 and guides the feeding of the wire 15 from the feeding reel 23 and the winding of the wire 15 to the take-up reel 24 while traversing.

The two reels 2 of the reel mechanism 22
By the rotation of the reels 3 and 24, the wire 15 is fed from the feed reel 23 to the cutting mechanism 11, and the processed wire 15 is wound on the take-up reel 24.

The tension applying mechanism 28 and the guide mechanism 29
It is arranged between the reel mechanism 22 and the cutting mechanism 11. Then, the processing rollers 13 and 14 of the cutting mechanism 11
Both ends of the wire 15 wound between them are mounted on the tension applying mechanism 28 via the respective guide rollers 30 of the guide mechanism 29. In this state, the tension applying mechanism 28 applies a predetermined tension to the wire 15 between the processing rollers 13 and 14, and the encoder 31 detects the tension of the wire 15.

As shown in FIGS. 1 and 3, a control device 34 constituting the control means is disposed adjacent to the device frame 12, and has a keyboard 35 on its front surface. The control device 34 includes a central processing unit (CPU) 36
And a read-only memory (ROM) 37 and a random access memory (RAM) 38. ROM3
7 stores various programs for controlling the operation of the entire wire saw. Further, the RAM 38 holds data relating to the cutting depth D and the cutting length L of the work 20 or the new line feed amount of the wire 15 corresponding to both the cutting depth D and the cutting length L.

The CPU 36 inputs the detection signal from the encoder 31 and the input data from the keyboard 35, and controls the motors 16, 25, 26, 21
A drive signal and a stop signal are output via the drive circuits 39 to 42. Then, when the shape or size of the work 20 is changed, the CPU 36 operates the keyboard 35 to operate the keyboard 35 to change the data of the new line feed amount of the wire 15 corresponding to the cutting depth D or the cutting length L of the work 20. When you type
The data is stored in the RAM 38.

Further, at the time of cutting the work 20, the CPU 36 determines the distance between the two working rollers 13 and 14 in accordance with the cutting depth D and / or the cutting length L of the work 20 based on the data stored in the RAM 38. The new line feed amount of the wire 15 is changed. In this case, the running speed of the wire 15 is adjusted by changing the rotation speed of the wire running motor 16 and the reel rotating motors 25 and 26, or
25, 26 is changed so that the wire 1
The new line feed amount is changed by adjusting the round trip time ratio in the bidirectional running of No. 5. Therefore, the wire traveling motor 16 and the reel rotating motors 25 and 26 adjust the traveling speed of the wire 15 based on the instruction from the control device 34 or adjust the reciprocating time ratio in the bidirectional traveling of the wire 15. This constitutes a wire traveling means for variably adjusting the new line feed amount.

Next, the operation of the wire saw configured as described above will be described. In this wire saw, the wire 15 is paid out from the pay-out reel 23 of the reel mechanism 22, intermittently reciprocates bidirectionally between the processing rollers 13 and 14 of the cutting mechanism 11, and then takes up the take-up reel 24.
It is wound up. For example, at the start of cutting, the wire 15 moves forward step by step, such as moving forward 10 m and moving backward 9 m. Therefore, the new line feed amount at the start of the cutting is 1 m for one round trip of the wire 15. Then, the work 20 is pressed against the wire 15 by the work supporting mechanism 19 while the slurry containing loose abrasive grains is supplied onto the wire 15 between the processing rollers 13 and 14. Thereby, the work 20 is cut into a predetermined thickness.

For example, FIG. 4 shows an example of a change pattern of the new line feed amount according to the cutting depth of the work 20. At the time of cutting in this case, the wire between the processing rollers 13 and 14 is controlled by the CPU 36 of the control device 34 based on the data stored in the RAM 38 according to the cutting depth of the work 20 as shown in FIG. Fifteen new line feed amounts are changed. As a method of changing the new wire feed amount of the wire 15, a method of adjusting the traveling speed of the wire 15 as shown in FIG. 5 and a method of changing the reciprocating time ratio in bidirectional traveling of the wire 15 as shown in FIG. Is adjusted, and one is selected as necessary.

That is, in the method of adjusting the traveling speed of the wire 15 (see FIG. 5), as the cutting depth of the work 20 increases, the rotation speed of the wire traveling motor 16 and the reel rotating motors 25 and 26 increases. Is changed, and the traveling speed of the wire 15 when traveling forward is increased. As a result, as shown in FIG.
To F2, and the new line feed amount of the wire 15 between the processing rollers 13 and 14 is increased. For example, in the initial stage of the cutting process, the new line feed amount was 1 m in the forward 10 m and the retreat 9 m, but thereafter, the cutting process is advanced. The amount of advance is larger than the amount of retreat of the wire 15, and the amount of new line feed corresponding to the difference between the amount of advance and the amount of retreat gradually increases.

In the method of adjusting the reciprocating time ratio in the bidirectional traveling of the wire 15 (see FIG. 6), as the cutting depth D of the work 20 increases, the wire traveling motor 16 and the reel rotating motors increase. 25 and 26 are changed. As a result, as shown in FIG. 6, the ratio between the forward traveling time and the backward traveling time is Ta1.
/ Tb1 is changed (increased) to Ta2 / Tb2, and the new line feed amount of the wire 15 between the processing rollers 13 and 14 is increased. More specifically, the forward travel times Ta1 and Ta2 before and after the change have a relationship of Ta1 <Ta2, while the return travel times Tb1 and Tb2 before and after the change.
Are in a relationship of Tb1> Tb2. Therefore, between the ratios, (Ta1 / Tb1) <(Ta2 / Tb2).
Incidentally, in the example of FIG. 6, (Ta1 + Tb1) = (Ta
2 + Tb2). Therefore, as the cutting depth D of the work 20 increases, the ratio of the forward traveling time gradually increases, and the new line feed amount corresponding to the difference between the forward movement amount and the backward movement amount of the wire gradually increases. When the new wire feed amount of the wire 15 increases as the cutting depth D increases, the cutting efficiency (sharpness) of the work 20 by the wire 15 is increased.
Is gradually increased. In other words, the loose abrasive particles are deposited on the wire 15 in a portion where the cutting history of the wire 15 is short,
In other words, the newer part is better, so the newer part is sharper.

Therefore, as shown in FIG. 7, as the cutting depth D of the work 20 increases in the processing direction and the thickness of the obtained wafer 20a tends to increase, the thickness of the obtained wafer 20a tends to increase. Is corrected by increasing the new wire feed amount of the wire 15. Therefore, according to the first embodiment, it is possible to cut a high-quality wafer having a uniform thickness as shown by a two-dot chain line in the cross section of the wafer in FIG.

The case where the new wire feed amount of the wire 15 is changed according to the cutting depth D of the work 20 (corresponding to the vertical feed amount of the work) has been described. (Corresponding to the horizontal width of the cut surface of the wire 15). Further, both factors of the cutting depth D and the cutting length L can be reflected in the change control of the new line feed amount. Incidentally, when cutting a cylindrical work 15 having a circular cross section, an increase in the cutting depth D results in an increase in the cutting length L in a cutting section from the cutting start point of the work to the center. Further, as shown in FIG. 7, as the workpiece cutting end point E is approached, the cutting length L of the workpiece gradually decreases, so that the sharpness of the workpiece gradually increases from the highest point of the contour line. Because of this tendency, the factor of the cutting length L is taken in from the vicinity of the cutting end point E to the factor of the cutting depth D, and for example, as shown by a two-dot chain line B in FIG. By controlling so as to suppress, it is possible to save the feed amount of the new line.

The effects that can be expected from the first embodiment are listed below. ○ In the wire saw of the first embodiment, the wire 15
When the workpiece 20 is cut, the amount of new wire feeding of the wire 15 between the processing rollers 13 and 14 is changed according to the cutting depth D (and / or the cutting length L) of the workpiece 20. Therefore, it is possible to effectively correct the tendency that the thickness of the cut wafer 20a tends to increase as the cutting depth D of the work 20 increases, and to make the thickness of the wafer 20a uniform. it can.

By adjusting the traveling speed of the wire 15, the amount of new wire feeding of the wire 15 between the processing rollers 13 and 14 is changed. For this reason,
The wire traveling motor 1 according to the cutting depth D of the work 20
Only by changing the rotation speeds of the motor 6 and the reel rotation motors 25 and 26, the tendency of the thickness of the wafer 20a to increase can be easily corrected.

By adjusting the reciprocating time ratio in the bidirectional traveling of the wire 15 by the control means (control device 34), the amount of new wire feeding of the wire 15 between the processing rollers 13 and 14 is changed. It has become. Therefore, the plate thickness of the wafer 20a tends to increase only by changing the reversal switching timing of the wire traveling motor 16 and the reel rotation motors 25 and 26 according to the cutting depth D of the work 20 as described above. Can be easily corrected.

The first embodiment may be modified and embodied as in the following modified example. (Modification Example 1) In the method of adjusting the traveling speed of the wire 15 shown in FIG. 5, the traveling speed of the wire 15 during the backward traveling is reduced, so that the backward traveling feed amount of the wire 15 is reduced, and , 14 to increase the new line feed amount of the wire 15.

(Modification 2) As a method of adjusting the traveling speed of the wire 15, the traveling speed of the wire 15 is increased both in the forward traveling and in the backward traveling, so that the new line feed amount is increased. To be configured. For example, in the initial stage of the cutting process, the new line feed amount was 1 m at a forward speed of 10 m and a reverse speed of 9 m. The new line feed amount should be 2m.

(Modification 3) In the method of adjusting the round trip time ratio in the bidirectional traveling of the wire 15 shown in FIG.
By increasing and changing only the forward traveling time of the wire 15, the reciprocating time ratio is increased, and the processing rollers 13 and 1 are increased.
A configuration in which the new line feed amount of the wire 15 between the four is increased.

(Modification 4) In the method of adjusting the reciprocating time ratio of the wire 15 shown in FIG. 6, the reciprocating time ratio is increased by reducing and changing only the return travel time of the wire 15 so as to increase the processing roller 13. , 14 between wires 1
5 to increase the new line feed amount.

(Modification 5) Instead of detecting the cutting length L of the work 20 from the program data, for example, by measuring a mechanical change such as tension or bending of the wire 15 or an electrical change such as a motor load. Detecting the cutting length L.

The same effects as those of the first embodiment can be obtained even with the configurations of the first to fifth modifications. (Second Embodiment) Another embodiment for cutting a wafer having a uniform thickness will be described. When cutting the work 20 while keeping the slice speed (work feed speed) constant without taking any measures, the thickness of the wafer 20a gradually increases from the cutting start point P of the work 20 toward the cutting end point. The tendency to increase is as described above (see FIG. 7). In the second embodiment, two control methods for making the wafer thickness uniform will be described. Here, in order to simplify the description, a case will be described in which the traveling of the wire 15 is not stepwise and is continuously traveling in one direction. The mechanical configuration of the wire saw used in the second embodiment is the same as that of the first embodiment,
7 and the contents of the control programs and data stored in the RAM 38 are different. Therefore, the description will focus on the control procedure executed by the CPU 36.

A first control method for making the wafer thickness uniform is to change the feed speed Vs of the work 20 with time according to the control characteristics shown in FIG. That is, while the traveling speed of the wire 15 is kept constant, the work feed speed Vs is gradually reduced in accordance with the increase in the cutting depth D of the work 20 from the cutting start point P of the work 20. According to such a gradual control of the work feed speed Vs, the deeper the cut of the wire 15 into the work 20, the deeper the traveling wire 1
The time of the relative vertical movement of No. 5 (that is, the time required to obtain a constant cutting amount) becomes relatively long. As a result, the same effect as the improved sharpness of the traveling wire 15 can be obtained, and unevenness in the thickness of the wafer due to wire cutting can be suppressed.

As described above, according to the first control method, it is possible to cut out the wafer 20a having excellent uniformity in thickness at each portion from the work 20. However, this method is disadvantageous in that it requires more time for cutting per work because the work feed speed Vs (slice speed) is intentionally reduced.

A second control method for making the wafer thickness uniform is to change the traveling speed of the wire 15 with time according to the control characteristics shown in FIG. That is, while keeping the work feed speed Vs constant, the traveling speed Vw of the wire 15 is gradually increased in accordance with the increase in the cutting depth D of the work 20 from the cutting start point P of the work 20. According to the progressive control of the wire running speed Vw, the deeper the wire 15 is cut into the work 20, the greater the lapping action based on the relative speed difference between the work 20 and the wire 15 at the cut site. As a result, the same effect as the improved sharpness of the traveling wire 15 is obtained, and the thickness unevenness of the wafer 20a due to the wire cutting is suppressed.

As described above, according to the second control method, it is possible to cut out the wafer 20a having excellent uniformity in thickness at each portion from the work 20. Also, this second
Since the control method of (1) keeps the workpiece feed speed Vs constant and does not decrease with time, there is no element for prolonging the cutting process, and it can be said that this method is more advantageous than the first control method.

Further, according to the second control method, the running speed of the wire 15 becomes relatively low at the start of cutting the work 20, so that the amount of frictional heat generated by the lapping action is very small. This is very advantageous in securing dimensional accuracy and dimensional stability of the cut wafer 20a. That is, if the amount of heat generated by friction from the initial stage of the cutting process of the work 20 is excessive, each wafer portion immediately after the cutting may be so warped that it cannot be ignored. If there is a warp that cannot be ignored after the completion of the wafer cutting, it goes without saying that the commercial value of the wafer is reduced. According to the second control method, the amount of frictional heat generated by the lapping action can be suppressed as much as possible during the cutting start period of the work 20 in which large warpage is likely to occur. Therefore, high-quality wafers can be cut by preventing or suppressing warpage of the wafers.

[0042]

Since the present invention is configured as described above, the following effects can be obtained. Claims 1, 2, 5, 6,
According to the inventions described in 7 and 8, the tendency of the thickness of the cut wafer to increase as the cutting depth or the like increases in the processing direction can be effectively corrected, and the uniform thickness can be increased. It becomes possible to cut a quality wafer.

According to the third aspect of the invention, the tendency to increase the thickness of the wafer can be easily corrected by adjusting the traveling speed of the wire and changing the new line feed amount. According to the fourth aspect of the invention, the tendency of increasing the thickness of the wafer can be easily corrected by adjusting the reciprocating time ratio in the bidirectional traveling of the wire and changing the new line feed amount. .

[Brief description of the drawings]

FIG. 1 is a plan view showing a mechanical configuration of a wire saw according to the present invention.

FIG. 2 is a front view of the wire saw shown in FIG. 1;

FIG. 3 is a block diagram showing a control circuit of the wire saw shown in FIG. 1;

FIG. 4 is a diagram showing a variable control state of a new line feed amount corresponding to a cutting depth of a work according to the first embodiment.

FIG. 5 is an explanatory diagram when a new line feed amount is adjusted by changing a traveling speed of a wire.

FIG. 6 is an explanatory diagram when a new line feed amount is adjusted by changing a wire reciprocation time ratio.

FIG. 7 is an explanatory view showing a change in the thickness of a wafer obtained when a cylindrical workpiece is cut by a conventional method.

FIG. 8 is a control characteristic diagram of a first control method according to the second embodiment.

FIG. 9 is a control characteristic diagram of a second control method according to the second embodiment.

[Explanation of symbols]

11: Cutting mechanism, 13: Processing drive roller, 14: Processing driven roller, 15: Wire, 16: Wire running motor, 19: Work support mechanism, 20: Work, 21: Work lifting / lowering motor, 22: Reel Mechanism, 23 ... pay-out reel, 24 ... take-up reel, 25, 26 ... reel rotation motor, 34 ... control device constituting control means, 36 ... CP
U, 37 ... ROM, 38 ... RAM.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Ishizuka 1 Shinmeicho, Yokosuka City, Kanagawa Prefecture Inside the Hihei Toyama Technical Center Co., Ltd.

Claims (8)

[Claims] 1. A wire saw in which a wire is wound at a predetermined pitch between a plurality of processing rollers and a workpiece is brought into contact with the wire while the wire is running to perform a cutting process. A wire saw provided with control means for changing the new wire feed amount of the wire according to the cutting depth of the work. 2. A wire saw in which a wire is wound at a predetermined pitch between a plurality of processing rollers, and a workpiece is brought into contact with the wire while the wire is running to perform a cutting process. A wire saw provided with control means for changing the new wire feed amount of the wire according to the cutting length of the work. 3. The wire saw according to claim 1, wherein the control means changes the new line feed amount by adjusting a traveling speed of the wire. 4. The wire saw according to claim 1, wherein the control means changes the new line feed amount by adjusting a round trip time ratio in bidirectional traveling of the wire. 5. A method for cutting a work, wherein a new wire feed amount of the wire is changed according to a cutting depth of the work, wherein the work is cut by moving the wire in an extending direction thereof. 6. A method for cutting a work, wherein a new wire feed amount of the wire is changed in accordance with a cutting length of the work, wherein the wire is moved in an extending direction to cut the work. 7. The running speed of the wire is increased in accordance with an increase in the cutting depth of the workpiece.
The method for cutting a workpiece according to the above. 8. The method according to claim 7, wherein the workpiece is fed at a constant speed to the traveling wire.