JPH10128737A - Method for cutting workpiece of wire saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cutting a workpiece of a wire saw for improving parallelism of a wafer to be cut. SOLUTION: A feeding direction of an ingot is switched in response to switching of a feeding direction of a reciprocatingly feeding wire. That is, when the wire is fed forward (period A to C), the ingot is fed in a direction for urging it to a wire row (period t1 ), while when the wire is fed backward (period D to F), the ingot is fed in a direction for separating it from the wire row (period t2 ). As a result, the ingot is cut only when the wire is substantially fed forward. The ingot is fed reversely, and hence a tapered part generated at the time of cutting (urging the ingot) can be skived by abrasive grains sufficiently supplied to its interior. As a consequence, the wafer with high parallelism can be cut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cutting a workpiece of a wire saw, and more particularly to a method of cutting a workpiece of a wire saw for cutting brittle materials such as silicon, glass, and ceramics.

[0002]

2. Description of the Related Art A wire saw is an apparatus for slicing a workpiece by a lapping action of abrasive grains supplied to a traveling wire row.

[0003]

By the way, in the above-mentioned wire saw, when cutting of the workpiece progresses and the length of contact between the wire and the workpiece increases, as shown in FIG.
The amount by which the abrasive grains 2 attached to the wire 1 advance into the workpiece decreases, and as a result, a phenomenon occurs in which the wafer 3 is cut into a tapered shape.

Further, in a wire saw for cutting a workpiece by reciprocating a wire, as shown in FIG. 7, a step (so-called saw mark) is generated on the surface of the wafer 4 when the direction of travel of the wire is switched. A phenomenon occurs. Wafers that have been cut in a tapered shape or that have a level difference require a lot of time in the subsequent lapping process, etc., in order to obtain the required degree of parallelism for the wafers, and the processing efficiency of the wafers is significantly increased. There is a disadvantage that it decreases.

The present invention has been made in view of such circumstances, and has as its object to provide a method for cutting a workpiece of a wire saw that can improve the parallelism of a wafer to be cut.

[0006]

According to the present invention, in order to achieve the above object, a wire which reciprocates between a pair of wire reels is wound around a plurality of grooved rollers to form a wire row. In a wire saw that cuts a workpiece into a number of wafers by pressing the workpiece while supplying a processing liquid to the row, a direction in which the workpiece is pressed against the wire row when the wire travels in the forward direction. When the wire travels in the backward direction, the workpiece is fed in a direction opposite to the direction in which the workpiece is pressed against the wire row, and the workpiece is cut while repeating this operation.

According to the present invention, the feed direction of the workpiece is switched in accordance with the switching of the traveling direction of the reciprocating wire. That is, when the wire is traveling in the forward direction, the workpiece is sent in a direction of pressing the wire row, and when the wire is traveling in the backward direction, the workpiece is sent in a direction away from the wire row. As a result, the workpiece is cut by being pressed against the wire row only when the wire is substantially traveling in the forward direction, but the workpiece is sent in a direction opposite to the pressing direction. Thereby, the abrasive grains can be sufficiently supplied to the inside of the workpiece, and the tapered portion generated during the cutting can be scraped off. Thereby, a wafer with high parallelism can be cut.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for cutting a workpiece of a wire saw according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of an embodiment of a wire saw 10 to which a workpiece cutting method according to the present invention is applied.

As shown in FIG. 1, a wire 14 wound around a wire reel 12 has a large number of guide rollers 16, 16,
Are wound around three grooved rollers 18A, 18B, 18C via a wire running path formed by... To form a horizontal wire row 20. Wire 14 forming wire row 20
Is wound on a wire reel (not shown) through a wire running path on the other side formed symmetrically with respect to the wire row 20.

A wire guide device 22, a dancer roller 24, and a wire cleaning device 26 are provided on each of the wire running paths formed on both sides of the wire row 20 (only one side is shown). The wire 14 is guided from the wire reel 12 at a constant pitch. Also,
The dancer roller 24 applies a certain tension to the traveling wire 14, and the wire cleaning device 26 removes the slurry attached to the wire 14.

The pair of wire reels 12 and the grooved rollers 18C are connected to motors (not shown) that can rotate forward and backward, respectively. The wires 14 drive these motors synchronously, The wire reel 12
Travels back and forth at high speed. A work feed table 28 that moves vertically with respect to the wire row 20 is installed above the wire row 20. The work feed table 28 is provided with a tilting device 30, and an ingot 32 as a workpiece is held at a lower portion of the tilting device 30 and set at an arbitrary tilt angle.

In the wire saw 10 configured as described above, the cutting of the ingot 32 is performed by lowering the work feed table 28 holding the ingot 32 and pressing the ingot 32 against the wire row 20 traveling at high speed. At this time, a slurry is supplied to the wire row 20 from a slurry tank 34 through a nozzle (not shown), and the ingot 32 is cut into wafers by a lapping action of abrasive grains contained in the slurry.

The slurry used for processing the ingot 32 is as follows:
The oil is collected in a slurry tank 34 via an oil pan 40 installed below the wire array 20, and is circulated and used while replenishing the shortage. At this time, the temperature of the slurry is increased by absorbing heat generated during processing, and the recovered slurry is cooled to a constant temperature by the heat exchanger 36. Next, a method of cutting a workpiece according to the present invention applied to the above-described wire saw 10 will be described.

In the wire saw 10 of the present embodiment, the ingot 32 is cut by reciprocating the wire 14. FIG. 2 is an example of a traveling pattern of the wire 14 when performing reciprocating traveling cutting. As shown in the figure, when performing reciprocating traveling disconnection, first, in the period A, the wire reel 12
And the motor connected to the grooved roller 18C is driven synchronously to drive the wire 14 at a steady running speed (+700 m /
min). Then, 1 shown in the period B in FIG.
This steady running speed is maintained for a minute. After a lapse of one minute, in the section C, the driving of each motor is stopped, and
To decelerate. At this time, the traveling speed of the wire 14 becomes 0 m / min for 3 seconds.

When the running speed of the wire 14 becomes 0 m / min, the rotation direction of each of the motors is reversed in the section D, and the wire 14 is accelerated to a steady running speed (-700 m / min) in 3 seconds. Let it. Then, this steady running speed is maintained for 40 seconds indicated by a period E in the figure. After a lapse of 40 seconds, the driving of each motor is stopped in the section F, and the wire 14 is caused to travel at a reduced speed. At this time,
The running speed of the wire 14 becomes 0 m / min for 3 seconds.

By repeatedly performing the above-described steps A to F, the wire 14 reciprocates between the pair of wire reels 12, and the wire feed amount in the forward direction (the above steps A to C) is larger in the backward direction (the above-described direction). Since the wire travel amount is larger than the wire feed amount in the steps D to F) (the steady traveling time is longer in the forward direction by 20 seconds than in the backward direction), as a result, the wire 14 is wound around one of the wire reels 12. .

Next, the feed pattern of the ingot 32 will be described. As shown in FIG. 3, when the wire 14 is traveling in the forward direction (the right direction in FIG. 3) (time t _{1 in} FIG. 4), the ingot 32 moves in the forward direction, that is, the direction pressed against the wire row 20. The wire 14 is traveling in the backward direction (left direction in FIG. 3) (time t in FIG. 4).
₂ ), the ingot 32 is sent in the opposite direction, that is, in the direction away from the wire row 20.

Here, since the ingot 32 needs to be cut in the forward direction, the ingot 32 is fed by
Set as follows. As shown in FIG. 4, at the beginning of cutting, while the wire 14 is accelerated to the steady running speed (section A), the feeding of the ingot 32 is stopped.
Next, after the wire 14 is accelerated to the steady running speed, 0
Until it becomes m / min (section B-C), and sends only the time (t ₁ -Δt) at a constant speed v ₁ of the ingot 32 in the forward direction. As a result, the ingot 32 moves in the positive direction Z ₁ = v
₁ * (t ₁ -Δt) (FIG. 3
(State of (a)).

The ingot 32 is moved at a constant speed v in the forward direction.
₁At time (t₁−Δt), the process of section BC,
Step 1. Next, the wire 14 travels in the backward direction,
Until the traveling speed becomes 0 m / min again (section
DEF), the ingot 32 is moved at a constant speed v in the reverse direction._Two
At time t _TwoJust send. As a result, the ingot 32
Z in direction_Two= V_Two* T_Two(Figure 3
(State of (b)).

The ingot 32 is moved at a constant speed v in the reverse direction.
The interval D-E-F Send ₂ only time t ₂ step and step 2. Here, the feed amount Z of the ingot 32 in the forward direction
V ₁ , v ₁ so that the feed amount Z _{2 in the} direction opposite to ₁ is constant.
Set ₂ . As a result, the ingot 32
By making one reciprocation of 4, 4 returns to the original position, that is, the starting position of cutting. In order for the ingot 32 to be newly cut in the next round trip from this state, it is necessary to return the ingot 32 to the position cut in step 1.

[0021] Send Therefore, while the wire 14 is accelerated until a steady running speed (section A '), at a constant speed v ₃ the ingot 32 in the forward direction by the time Delta] t. As a result, the ingot 32 is fed in the forward direction by Z ₃ = v ₃ * Δt. However, in order to return the ingot 32 to the position cut in step 1, Z ₃ = Z ₁ v
You only need to set ₃ . As a result, the ingot 32 returns to the position cut in step 1 in this section A '.

The ingot 32 is moved in a forward direction at a constant speed v.
When the process of the section A 'sent in ₃ by a time Δt to Step 3, below, described above, by repeating steps 1-3, the ingot 32 is cut by Z ₁ each time the wire 14 reciprocates once Will go. That is,
Ingot 32 is cut in step 1 by Z _1,
In step 2, the amount cut in step 1 (Z ₁ )
Only in the opposite direction, and further in step 3 to the position cut in step 1 above. By repeating this process, the ingot 32 becomes possible to repeatedly cut by Z _1.

Ingot 32 sent as described above
Is cut as follows. The ingot 32 is sent toward the wire row 20 traveling in the forward direction, and is cut by the lapping action of the abrasive supplied to the wire row 20. Decrease in the direction of travel in the downstream direction. As a result, FIG.
As shown in (a), a phenomenon occurs in which the wafer 32w is cut into a tapered shape.

However, as in the cutting method of the present embodiment, when the traveling direction of the wire 14 is switched,
By switching the feed direction of the ingot 32, the tapered portion can be removed. That is, by sending the ingot 32 in the direction opposite to the pressing direction,
The wire 14 passes through the cut groove 32G of the ingot 32 that has already been cut. As a result, the wire 14
The abrasive particles adhered to the ingot 32 are sufficiently supplied to the inside of the ingot 32, and the abrasive particles sufficiently supplied to the inside of the ingot 32 scrape off the tapered portion formed at the time of cutting (when pressing the ingot). be able to.

At this time, since the wire 14 is traveling in the opposite direction, the rightmost portion in the figure where the uncut portion is the most left is
Most abrasive grains are supplied. Therefore, the tapered portion can be uniformly removed as a whole. in this way,
By switching the feeding of the ingot 32 in accordance with the switching in the running direction of the wire 14, the tapered portion formed at the time of cutting (when the ingot is pressed) is all scraped off at the time of feeding in the reverse direction. Therefore, at the end of cutting, a wafer 32w with extremely high parallelism is obtained.

As described above, according to the cutting method of the present embodiment, the wafer 32w having extremely high parallelism is cut, and as a result, the grinding time in the subsequent lapping step and the like is reduced, and the processing efficiency of the wafer 32w is reduced. improves. In addition, wafer 3
Since no irregularities such as saw marks are formed on the surface of 2w,
After the cutting is completed, the operation of extracting the wafer 32w from the wire row 20 can be performed smoothly.

[0027]

As described above, according to the present invention,
By switching the feed direction of the workpiece in accordance with the switching of the traveling direction of the reciprocating wire, a wafer with high parallelism can be cut.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a wire saw.

FIG. 2 is an explanatory diagram showing an example of a running pattern of a wire.

FIGS. 3A and 3B are explanatory diagrams for explaining an ingot feed pattern; FIGS.

FIG. 4 is a graph showing a relationship between a wire running pattern and an ingot feeding pattern.

FIGS. 5A and 5B are explanatory diagrams illustrating a cutting state of an ingot.

FIG. 6 is an explanatory view illustrating a cutting state of a conventional ingot.

FIG. 7 is an explanatory view illustrating a cutting state of a conventional ingot.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wire saw 12 ... Wire reel 14 ... Wire 16 ... Guide roller 18A-18C ... Grooved roller 20 ... Wire row 28 ... Work feed table 30 ... Tilting device 32 ... Ingot 32G ... Cutting groove 32w ... Wafer

Claims (1)

[Claims] 1. A wire that reciprocates between a pair of wire reels is wound around a plurality of grooved rollers to form a wire row, and a workpiece is pressed while supplying a working fluid to the wire row. In a wire saw for cutting the workpiece into a number of wafers, when the wire travels in the forward direction, the workpiece is sent in a direction to press the wire row, and when the wire travels in the backward direction, the workpiece A workpiece is cut in a direction opposite to a direction in which the workpiece is pressed against the wire row, and the workpiece is cut while repeating this operation.