JP2013255977A - Wire for wire saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form concave parts for holding grinding particles on a surface of a wire for a wire saw not by passing a step for physically pushing and pressing.SOLUTION: Brass plating is applied to a surface of a wire 10 and is subjected to electrolytic polishing processing, thereby concave parts 12a for holding grinding particles g are formed on the surface of a brass plating layer 12. Strength is not greatly lowered and the breakage of the wire 10 can be prevented different from the case of physically forming the concave parts by pushing and pressing or others because of chemically forming the concave parts 12a. It is possible to easily change the size of the concave parts 12a by adjusting a current value and an immersing time in the electrolytic polishing processing. The damage of the wire 10 accompanied by rolling of the grinding particles can be suppressed g because the grinding particles g do not roll by matching the size of the concave parts 12a to an average particle size selected when cutting.

Description

  The present invention relates to a wire used in a wire saw.

  A wire saw is known as a cutting device used for a hard material cutting operation (slicing operation) such as an operation of cutting a silicon wafer from a silicon ingot.

A wire saw is made by winding a large number of wire saw wires in parallel between opposing rolls, running the wound wire at a high speed by rotating the roll, and pressing a material to be cut such as a silicon ingot against the running wire. It is a mechanism for cutting.
Here, since the wire itself has poor cutting ability, during the above operation, abrasive grains (cutting fluid in which abrasive grains are dispersed) are supplied to the traveling wire (free abrasive system).

Therefore, in the cutting operation, the cutting efficiency improves as the amount of abrasive grains drawn into the material to be cut along with the wire increases.
One way to improve the cutting efficiency is to improve the ability of the wire to hold the abrasive grains on the surface.

For this reason, as described in Patent Documents 1 to 3, in the wire manufacturing process, a concave portion is physically formed on the surface of the wire by pressing the wire between rolls provided with irregularities. It is done.
Since the abrasive grains supplied at the time of cutting work fit into the recesses provided on the surface of the wire, the abrasive grain holding ability of the wire is improved.

By the way, in the wire saw, since the material to be cut is pressed against the traveling wire and cut, the size of the cutting allowance of the material to be cut depends on the wire diameter.
Therefore, the yield at the time of cutting | disconnection improves, so that a wire is reduced in diameter.

However, in general, a thin wire is uneasy in terms of strength. If this wire is further pressed between the rolls and physically pressed, the mechanical strength of the wire will be further reduced, such as wire breakage. The danger is greatly increased. In general, when the wire diameter is reduced, the pulling performance of the abrasive grains decreases.
In Patent Documents 2 and 3, in order to suppress the decrease in mechanical strength, the amount of pressing by the roll is reduced and the concavity becomes shallow and flat, but the wire is physically attached by the roll. As long as the pressing is performed, the mechanical strength cannot be completely reduced.

Japanese Patent No. 3923965 JP 2007-44841 A JP 2001-205551 A

  Therefore, a problem to be solved by the present invention is to form a recess for holding abrasive grains on the surface of a wire saw wire, particularly a small-diameter wire, without undergoing a physical pressing step.

  In order to solve the above-mentioned problems, in the wire saw wire of the present invention, the surface is subjected to brass plating, and this is subjected to an electropolishing treatment to chemically form a recess for holding abrasive grains on the surface of the plating. It was.

  That is, the wire saw wire of the present invention is composed of a drawn steel wire and a brass plating layer formed on the surface of the steel wire, and the brass plating layer is formed by an electropolishing treatment. The surface has a large number of recesses into which abrasive grains can fit. It is preferable that the surface of the steel wire is exposed at the bottom of the concave portion of the brass plating layer.

Each recess of the brass plating layer preferably has a depth of 0.5 to 3.0 [mu] m and a width of 6.0 to 9.0 [mu] m as a size that suitably holds a commonly used abrasive grain. .
As a wire, the thing of a thin diameter is mainly assumed and it is preferable that it is 0.1-0.2 mm.

  Since the concave portion is chemically formed on the surface of the wire saw wire by electrolytic polishing, the strength is not greatly reduced unlike the case where the concave portion is physically formed by pressing the roller or the like. Therefore, even when the wire has a small diameter, disconnection or the like can be prevented.

  By adjusting the current value and immersion time in the electropolishing process, it is possible to easily change the dimensions of the recesses, and to optimize the dimensions according to the average grain size of the abrasive grains selected during the cutting operation. it can.

  When the steel wire is exposed to the surface of the wire through the recess by the electrolytic polishing treatment, the wettability is increased, and the abrasive grains are likely to become familiar with the cutting fluid, so that the abrasive grains are easily drawn and the cutting efficiency is improved.

The schematic diagram which shows the state by which the abrasive grain was hold | maintained at the wire for wire saws of embodiment The flowchart which shows the outline | summary of the whole manufacturing process of the wire for wire saws of embodiment. The schematic diagram which shows the electropolishing process in the manufacturing process of the wire for wire saws of embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the wire saw wire 10 according to the embodiment includes a drawn steel wire 11 and a brass plating layer 12 formed on the surface of the steel wire 11.
As shown in the figure, a large number of small recesses 12a are formed on the surface of the brass plating layer 12 by electrolytic polishing.
Therefore, when the abrasive grains g are supplied during the cutting operation using the wire saw wire 10, the abrasive grains g fit into the recesses 12 a as shown in the figure, and the abrasive holding ability of the wire is improved. Yes.
It is preferable that the surface of the steel wire 11 is exposed at the bottom of the recess 12a because the wettability of the wire saw wire 10 is improved.

Although the wire diameter of the wire saw wire 10 is not particularly limited, it is mainly assumed that the wire diameter is 0.04 to 0.20 mm.
The thickness of the brass plating layer 12 is not particularly limited, but can be about several μm.

The size of the recess 12a formed in the brass plating layer 12 is not particularly limited, but if it is adjusted to the average grain size of abrasive grains in a general-purpose cutting fluid, the abrasive grains g stuck in the recess 12a are transferred. It can suppress moving. Therefore, it is possible to prevent the wire 10 from being worn with the rolling of the abrasive grains g, and the abrasive grains g are firmly held by the wires, so that the cutting efficiency is improved.
Since the average grain size of general abrasive grains g is about several μm to several tens of μm, particularly about 15 μm, the width and depth of the recesses are also about several μm to several tens of μm, particularly 15 μm. As the size in which the abrasive grains g are sufficiently fitted and the strength of the wire 10 is not lowered, the width is preferably 6 μm to 9 μm and the depth is preferably 0.5 μm to 3 μm.
If the entire abrasive grain g gets stuck in the recess 12a, the abrasive grain g is less likely to contact the object to be cut and the cutting efficiency is reduced, and when the abrasive grain g gets only a little in the recess 12a, The abrasive g is not firmly held by the wire 10 and may cause rolling. Therefore, it is preferable that the volume of the recess 12a is a size in which 1/4 to 1/2 of the abrasive grains g are fitted.

For example, as shown in FIG. 2, the wire saw wire 10 according to the embodiment prepares a widely used steel wire 11, and performs a primary wire drawing step S <b> 1, a patenting step S <b> 2, a brass plating step S <b> 3, a finish wire drawing step S <b> 4, electrolysis. It is manufactured through the polishing step S5.
Although the kind of steel wire 11 is not specifically limited, The carbon content can illustrate a high carbon wire with 0.80 mass% or more.
Since the primary wire drawing step S1, the patenting step S2, the brass plating step S3, and the finish wire drawing step S4 are the same as in the prior art, the details are omitted, and the electropolishing step S5 will be described in detail below.

  The steel wire 11 that has undergone the primary wire drawing step S1, the patenting step S2, the brass plating step S3, and the finish wire drawing step S4 is a feed roller attached to the electropolishing apparatus 20 in the electropolishing step S5 as shown in FIG. 23, it is drawn into the electrolytic solution tank 21 in which the acidic electrolytic solution 21a is accommodated. The steel wire 11 immersed in the electrolytic solution tank 21 passes through the electrode plate 22 disposed in the electrolytic solution tank 21 and is sent out of the electrolytic solution tank 21.

Here, in the electropolishing apparatus 20, the steel wire 11 subjected to the brass plating is used as a cathode, for example, and the electrode plate 22 is used as an anode, for example, and a current is passed, and a part of the brass plating layer 12 is ionized to be an electrolytic solution. It will melt into 21a.
Originally, very fine irregularities are inevitably formed on the brass plating layer 12 of the steel wire 11, and the current concentrates on the edge portions of the irregularities, so the recessed portions are preferentially and selectively electropolished. As a result, the recesses become large, and a large number of recesses 12a of the brass plating layer 12 are formed.

Here, the size of the concave portion can be freely changed by adjusting the immersion time and the current value of the steel wire 11 in the electrolytic solution tank 21.
The immersion time is not particularly limited, but if it is too long, not only the concave portion of the brass plating layer 12 but also the entire surface is electropolished and the surface becomes smooth. On the other hand, if it is too short, the electrolytic polishing is not performed so much and the concave portion is not formed. About 30 seconds to 60 seconds is preferable because the size cannot be sufficient for holding the abrasive grains.
For the same reason, the current value is not particularly limited, but is preferably 0.5 A to 1.0 A (ampere).
Although the kind of acidic electrolyte solution is not specifically limited, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and these liquid mixture can be illustrated.

  Hereinafter, examples of the present invention and comparative examples will be given to further clarify the contents of the invention.

For the wire having a wire diameter of 0.13 mm subjected to brass plating, an electrolytic polishing treatment was performed at a current value (A) and an immersion time (second) in an electrolytic solution as shown in Table 1 below. Wires for wire saws of Examples 1 to 4 and Comparative Example, each having a concave portion having a size (μm) on the surface thereof, were formed.
Here, a mixed solution in which water, sulfuric acid, and phosphoric acid were mixed at a weight ratio of 5: 6: 50 was used as the electrolytic solution.

Next, using the wires for wire saws of Examples 1 to 4 and Comparative Example, a glass ingot cutting test was performed while supplying commonly used abrasive grains having an average particle diameter of 15 μm, and the cutting speed (mm / min) ) Was measured. The results are shown in Table 2.
As can be seen from Table 2, in Examples 1 to 4, the cutting speed was significantly improved as compared with the comparative example.

  It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications and variations within the scope and meaning equivalent to the terms of the claims.

10 Wire for Wire Saw of Embodiment 11 Steel Wire 12 Brass Plating Layer 12a Recess 20 Electrolytic Polishing Device 21 Electrolytic Solution 21a Electrolytic Solution 22 Electrode Plate 23 Feed Roller g Abrasive Grain

Claims (4)

It consists of a drawn steel wire and a brass plating layer formed on the surface of the steel wire,
The brass plating layer is a wire saw wire having a large number of concave portions formed by electrolytic polishing treatment into which abrasive grains can be fitted.   The wire for a wire saw according to claim 1, wherein a surface of the steel wire is exposed from a bottom of the concave portion of the brass plating layer.   The wire for a wire saw according to claim 1 or 2, wherein each of the recesses has a depth of 0.5 to 3.0 µm and a width of 6.0 to 9.0 µm.   The wire for a wire saw according to any one of claims 1 to 3, wherein the wire diameter is 0.1 to 0.2 mm.

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