JP2013176814A - Saw wire with excellent cutting property, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a saw wire with excellent cutting property which can compatibly secure the required elasticity of the wire, and consistency to a wire curl, and a method for manufacturing the same.SOLUTION: It is found that a saw wire with an excellent cutting property can be obtained by setting tensile strength at ≥3,900 MPa, a 0.2%-yield stress ratio in a range of 94-98%, and a free coil diameter at ≥300 mm. Wet drawing work is executed by setting an approach angle at 8-10° and a one-pass reduction rate in a range of 16-22% in a final die, and setting the approach angle at 4-8° and the one-pass reduction rate in a range of 16-22% in a die other than the final die. Thus, the saw wire with the excellent cutting property can be manufactured.

Description

The present invention relates to a saw wire suitable for manufacturing a wafer-like plate by slicing a hard and brittle material such as a semiconductor ingot such as a silicon ingot, crystal, and sapphire, and a manufacturing method thereof.

Conventionally, a saw wire cutting operation has been used to produce a wafer-like plate by slicing a hard and brittle material such as a semiconductor ingot such as a silicon ingot, crystal, and sapphire.

Saw wire is hung at a predetermined interval on the main roller of a wire saw machine that cuts silicon ingots, etc., and runs at a high speed while spraying a slurry of hard abrasives such as diamond and a special oily or aqueous agent. By doing so, an object to be cut such as a silicon ingot is cut.

FIG. 1 shows a schematic diagram of a wire saw machine. In the wire saw machine, the saw wire 1 supplied from the supply reel 2 is wound around the main roller 3 several times and travels at a high speed.
At this time, the saw wire 1 is in a high tension load state between the main rollers 3. When the workpiece 6 is pressed from above, the workpiece 6 is ground and thinly sliced by the sprayed slurry 5.
The used saw wire 1 is wound up on the discharge reel 4.

When a workpiece is cut using a saw wire, the characteristics required of the saw wire are wires that can obtain good wafer quality and have a low risk of disconnection during cutting. In order to obtain good wafer quality, it is effective to set the wire tension between the main rollers of the cutting machine as high as possible to stabilize the wire trajectory at the time of cutting while maintaining the straight shape of the wire.

Therefore, the characteristic required for saw wires is high strength.
In addition, the saw wire is required to have a good wire habit (a coiled habit having a uniform diameter of about 300 mm that does not change in the longitudinal direction of the wire). For example, if the wire diameter is poor, for example, if the coil diameter is small or if it is a spiral shape, even if high tension is applied to the wire, it will not be possible to maintain the straight shape, which will reduce the wafer accuracy. End up.

Normally, the wire at the time of cutting is used in a state where it is stretched with a tensile tension within the elastic range, but if for some reason the wire between the main rollers of the saw machine is momentarily subjected to a tension exceeding the elastic range, it will be plastic. Elongation occurs and slack occurs in the wire between the main rollers, which causes the wafer surface accuracy to deteriorate. When the wafer surface accuracy deteriorates, the restoration polishing takes a long time, and when the wafer cannot be repaired, the object to be cut is discarded.

Therefore, a wire having high strength and a high 0.2% yield strength ratio is desired, but if the 0.2% yield strength ratio is too high (plastic elongation is too small), excessive tension is instantaneously applied to the wire during cutting. Therefore, the characteristics of the saw wire excellent in the cutting property are high strength, have a good wire habit, and do not break during cutting. Japanese Patent No. 3814070 discloses a high-strength ultrafine steel wire having high strength and excellent ductility.
Further, in the case of drawing a steel hard wire, the approach angle of the die has been widely adopted as an angle that minimizes the drawing force from the relationship between the cross-section reduction rate and the drawing force.

Japanese Patent No. 3814070

The saw wire is used in a state where it is stretched with a tensile tension in the elastic region at the time of cutting. However, if the wire receives a tension exceeding the elastic region for some reason, plastic elongation occurs and the wire between the main rollers This causes slack in the wafer surface, which deteriorates the wafer surface accuracy. Therefore, a wire having a high 0.2% proof stress ratio is desired. However, if the 0.2% proof stress ratio is too high, there is a problem in that wire breakage occurs when excessive tension is applied to the wire. It was. Further, if the wire line is poor, there is a problem that even if a high tension is applied to the wire, the straight shape cannot be maintained and the wafer accuracy is lowered.

An object of the present invention is to provide a saw wire excellent in cutability and a method of manufacturing the same, which can solve the above-described problems, and can secure a necessary elasticity value of the wire and can achieve both stability with respect to the wire habit. is there.

That is, the saw wire of the present invention has a tensile strength of 3900 MPa or more, a 0.2% proof stress ratio in the range of 94 to 98%, and a free coil diameter of 300 mm or more.

In addition, the method of manufacturing the saw wire, when the wire obtained by performing heat treatment and plating on the steel wire, and then drawing to an intermediate diameter, when performing wet drawing using a die,
The final die has an approach angle of 8-10 ° and a 1-pass area reduction of 16-22%.
The dies other than the final die are characterized in that the approach angle is set to 4 to 8 °, and the wet drawing is performed in a range of 1 to 22% in a 1-pass area reduction.

According to the manufacturing method of the present invention, it is possible to manufacture a saw wire that has good cutting wafer surface accuracy, can reduce disconnection during cutting, has good cutting performance, and high productivity during manufacturing.

FIG. 1 is a schematic view of a wire saw machine. FIG. 2 is a schematic view of a die used for wet wire drawing of the present invention. FIG. 3 is a schematic diagram of a wet wire drawing machine.

Hereinafter, a preferred embodiment of the saw wire according to the present invention will be described together with a manufacturing method thereof with appropriate reference to the drawings.

Here, in the present invention, the 0.2% proof stress ratio is the following general formula (1),
0.2% yield strength ratio = (0.2% yield strength / tensile strength) × 100 [%] (1)
Indicated by
The die approach angle is the angle α in FIG.
The present invention relates to a saw wire manufacturing method,
When the wire 7 obtained by performing heat treatment and plating on the steel wire and then drawing to an intermediate diameter is wet-drawn with a die after heat treatment, the final die 11 uses a die with an approach angle of 8 to 10 °, In addition, the one-pass area reduction rate is in the range of 16 to 22%, the die 10 other than the final die is a die having an approach angle of 4 to 8 °, and the one-pass area reduction rate is in the range of 16 to 22%. It is characterized by processing. Here, the total area reduction rate in the wet wire drawing is 95% or more.

When a die with a small approach angle (approach angle 4 to 8 °) is used, the processing depth becomes large, so that a wire having a high strength and a high 0.2% yield strength ratio can be manufactured. When a die with a small approach angle is used, the variation in the line distortion increases, so that the final die 11 uses a die with an approach angle of 8 to 10 ° to ensure a good line defect.
If the approach angle is less than 4 °, the frictional force at the time of drawing increases, the drawing resistance increases, and disconnection occurs frequently, so the approach angle is set to 4 ° or more.

Moreover, by taking a 1-pass area reduction ratio, it is possible to manufacture a wire having a high strength and a high 0.2% yield strength ratio.
If the 1-pass area reduction ratio is less than 16%, high strength cannot be expected. If the 1-pass area reduction ratio exceeds 22%, there is a high possibility that the strands will stick to the die, so the 1-pass area reduction ratio is in the range of 16 to 22%. .

The tensile strength of the saw wire is preferably 3900 MPa or more.

If the 0.2% proof stress ratio of the saw wire exceeds 98%, the plastic elongation becomes too small, and this causes wire breakage when an excessive tension is momentarily applied to the wire during cutting. The following is preferable. More preferably, the 0.2% yield strength ratio is in the range of 94-98%.

The free coil diameter of the saw wire is preferably 300 mm or more.

The steel wire is preferably a high strength material such as a high carbon steel wire or a piano wire.

Plating is preferably brass plating or the like in order to facilitate wire drawing.

As described above, according to the saw wire manufacturing method of the present invention, the dies other than the final die have an approach angle of 4 to 8 ° and a one-pass area reduction rate of 16 to 22%. Thus, the strength and the 0.2% proof stress ratio can be increased, and the final die has an approach angle of 8 to 10 ° and a 1-pass area reduction ratio in the range of 16 to 22%. It is possible to manufacture a saw wire having a good wire habit while controlling the yield strength ratio.
Furthermore, since the tensile strength of the wire manufactured by this method is 3900 MPa or more and the 0.2% proof stress ratio is in the range of 94 to 98%, the strength is high and the plastic elongation is not too small. Therefore, wire breakage during cutting can be reduced.
Therefore, this saw wire has high strength, and the 0.2% proof stress ratio is not too high, and the wire habit is good, so that it can be cut with high tension at the time of cutting, and the wafer surface accuracy is good. You can get things.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail according to an Example, this invention is not limited to a following example.

<Example 1>
In Examples, a high carbon steel wire rod having a wire diameter of 5.5 mm containing 0.8% by weight of carbon was subjected to wire drawing to an intermediate diameter of 0.80 mm, and after heat treatment, the conditions shown in Table 1 below were applied. Wet drawing was performed to a wire diameter of 0.12 mm. Table 1 shows that the one-pass area reduction ratio in wet wire drawing is 14%, 19%, and 24%. The final die approach angles are 3 °, 6 °, 9 °, 12 °, and the die approach angles other than the final die. Is the tensile strength (MPa) of the saw wire obtained under the conditions of 3 °, 6 °, 9 °, and 12 °, 0.2% yield strength ratio (%), wire wetting stability, wire breaking rate index, The wafer accuracy index of the wafer cut with the saw wire is shown. The linear stability is a better index as the numerical value is larger than 100 in the conventional example, and 100 or more is acceptable. In this case, the condition that the coil diameter is 300 mm or more and the variation within the class is smaller than that of the conventional case is set to be 100 or more.
The drawing rate index at the time of wire drawing is a better index as the numerical value is smaller as 2.3 in the conventional example, and the wafer accuracy index is a better index as the numerical value is larger as 100 as the conventional example.

As can be seen from Table 1, the examples have improved tensile strength, 0.2% yield strength ratio, wire wrinkling stability, wire breakage rate index, and wafer accuracy index compared to the conventional example. The tensile strength, which is a characteristic of a saw wire excellent in cutting property, is 3900 MPa or more and high strength, the range of 0.2% proof stress ratio is 94 to 98%, and the wire habit is good. And saw wire with excellent cutting performance could be manufactured.
It was confirmed that those manufactured under other conditions did not satisfy the above characteristics.

<Example 2>
Table 2 shows that the one-pass area reduction ratio in wet drawing is 17%, 19%, and 21%, the approach angle of the final die is 8 °, 10 °, and the approach angles of dies other than the final die are 5 °, 7 ° The results are shown.

From Table 2, in all the examples, the tensile strength, 0.2% yield strength ratio, wire wrinkling stability, wire drawing breakage index, and wafer accuracy index are improved in all conditions as compared to the conventional example. Produces a saw wire with excellent cutting properties, satisfying that the tensile strength is 3900 MPa or more, high strength, the 0.2% yield strength range is 94 to 98%, and the wire habit is good. We were able to.

It should be understood that the forms and examples for carrying out the invention disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Saw wire 2 Supply reel 3 Main roller 4 Discharge reel 5 Slurry 6 Cut object 7 Element 8 Die 9 Drive capstan 10 Dies other than the final die 11 Final die α Approach angle

Claims (2)

A saw wire having a tensile strength of 3900 MPa or more, a 0.2% proof stress ratio in the range of 94 to 98%, and a free coil diameter of 300 mm or more. A method for producing a saw wire obtained by subjecting a wire obtained by heat treatment and plating to a steel wire, followed by wire drawing to an intermediate diameter, and wet drawing with a die,
In the wet wire drawing step, the final die has an approach angle of 8 to 10 ° and a one-pass area reduction rate in a range of 16 to 22%.
The method for manufacturing a saw wire according to claim 1, wherein dies other than the final die have an approach angle of 4 to 8 ° and a one-pass area reduction rate of 16 to 22%.