JPH11277398A - Brittle material cutting wire tool and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diamond electrodeposited wire tool capable of feeding processing lubricant sufficiently to a processing part, easy to manufacture and excellent in processing efficiency and durability. SOLUTION: A plurality of strands are twisted so as to be formed into a core wire, and abrasive grains are electrically deposited uniformly to the surface of the core metal. The number of the strands is desirably to be 2 to 3. As abrasive grains, diamond abrasive grains are considered suitable, the core wire where a plurality of the strands 1 are twisted in advance, is submerged in a nickel plating tank filled with abrasive grains 3, so that the abrasive grains 3 are electrically deposited uniformly over the surface of the core wire. The twisting of a plurality of the strands thereby allows trough parts in a spiral shape formed mutually among the strands to be formed into passages for processing lubricant and chips. The diameter of each strand will be smaller than that of a single strand, the strands are desirably twisted in such a way that each strand itself is not twisted when they are twisted as a whole, because, in case of a piano wire, the smaller diameter of a wire is more subject to greater tension force per unit area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire tool used for cutting a brittle material such as single crystal silicon, quartz, amorphous silicon, etc., and uses abrasive grains electrodeposited on the surface of a core material such as a piano wire. The present invention relates to a wire tool for cutting and cutting a (workpiece) and a method for manufacturing the same.

[0002]

2. Description of the Related Art Semiconductor devices use brittle materials such as single crystal silicon used for IC substrates, quartz used for oscillators, and amorphous silicon used for solar cells and optical sensors. The technology for producing high-purity, high-precision, and low-cost products is extremely important as a technology that supports the advanced electronics society. One of the processing steps of a brittle material necessary for manufacturing a semiconductor device includes a slicing processing step of cutting a large number of thin wafers from an ingot. In slicing processing, it is required to reduce as much as possible defects and crack layers due to processing, and an abrasive grain processing method is widely used as a processing method satisfying the requirements.

[0003] There are a fixed abrasive method and a free abrasive method as abrasive processing methods, and an inner peripheral blade saw of a fixed abrasive method and a multi-wire saw of a free abrasive method are mainly used for cutting brittle materials. It is used for The fixed abrasive method has a high cutting efficiency per tool, but has disadvantages such as a reduction in processing efficiency as processing is repeated due to wear and clogging of abrasive grains, and a large processing crack. Further, the inner peripheral blade saw has a drawback that there is a limit to increasing the size of the blade corresponding to an increase in the diameter of the ingot, and it is difficult to realize a multi-saw that performs simultaneous machining with a large number of tools.

On the other hand, a wire saw can easily realize a multi-saw by winding a long wire a plurality of times between two multi-groove pulleys, and can improve the processing efficiency by cutting a large number of wafers simultaneously. It is easy to cope with a large diameter ingot. However, in the loose abrasive method, the processing efficiency per wire is poor, and the processing is performed while a large amount of a working fluid (slurry) containing abrasive grains flows out. In addition, a problem of disposal of the used slurry occurs.

Therefore, a diamond electrodeposited wire has been proposed as a tool having both the advantages of a wire saw and the advantages of a fixed abrasive system. This is a tool in which diamond abrasive grains are electrodeposited by nickel plating on the surface of a core wire such as a piano wire.Since this is a fixed abrasive type tool, a much higher cutting efficiency can be obtained compared to a free abrasive type wire saw. In addition, there is an advantage that cutting can be performed using a highly fluid working fluid such as light oil or water. However, it is difficult to manufacture a long wire tool because the production of the diamond electrodeposited wire tool is troublesome and expensive, and the cutting is performed using a shorter wire compared to the case of the free abrasive method. Machining is performed, the cutting load per wire unit length is large, and the machining efficiency decreases due to abrasion, falling off, clogging, etc. of the abrasive grains during repetition of machining, and the wire tension caused by the increase in machining load There is a problem that a wire cutting accident occurs due to an increase in the number of wires.

Therefore, the inventors of the present invention have made diamond abrasive grains spiral around the core wire for the purpose of further improving the cutting efficiency of the electrodeposited diamond wire tool and extending the life of the wire tool. A wire tool has been proposed in which a groove is formed in a portion that is electrodeposited and the abrasive grains are not electrodeposited. According to such a tool, since the machining fluid is smoothly supplied to the machining portion through the groove on the surface of the wire, the chips are washed away, and wear and clogging of the abrasive grains can be reduced, and the diamond electrodeposited wire tool is used. Can contribute to the improvement of the processing efficiency and the extension of the service life.

[0007]

However, a tool in which abrasive grains are spirally electrodeposited on the surface of a wire has a step of applying a spiral masking to the surface of the wire or a step of forming a spiral groove on the surface of the wire. Requires extra steps and it is relatively difficult to increase the productivity of those steps. As a result, there has been a problem that the manufacturing cost is increased and the tool cannot be supplied at a low cost. Also, in order to supply the machining fluid to the machining area sufficiently, the groove on the surface of the wire must be deepened, and the strength of the wire is reduced due to the decrease in the cross-sectional area of the wire and the concentration of stress, and the wire is easily broken. In order to avoid this, if the wire is made thicker, there is a dilemma that the processing efficiency and the yield of the material decrease due to an increase in the amount of material cut off during slicing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and has an object to obtain a diamond electrodeposited wire tool for cutting brittle materials, which enables a sufficient supply of a working fluid to a working portion and makes the tool more efficient. It is an object of the present invention to obtain an abrasive grain electrodeposited wire that can be manufactured well and easily, and has more excellent processing efficiency and durability when cutting a material.

[0009]

According to the present invention, there is provided a wire tool in which a plurality of strands 1 are twisted to form a core wire 2 and abrasive grains 3 are uniformly electrodeposited on the surface of the core wire. The above-mentioned problem has been solved. The material of the element wire 1 forming the core wire includes a metal wire material having a high tensile strength as with the conventional core wire,
Generally, a piano wire is used. The number of the wires 1 forming one core wire 2 is preferably two or three. Abrasive grain 3
Is suitable for diamond abrasive grains. A core wire 2 formed by twisting a plurality of strands 1 in advance is passed through a nickel plating tank 35 filled with abrasive grains 3 so that the surface of the core wire 2 is uniformly coated with the abrasive grains 3.
Electrodeposit.

As shown in FIGS. 1 and 2, the obtained wire tool has a structure in which abrasive grains 3 are electrodeposited on the exposed surface of the twisted strand 1 via a nickel plating layer 4. Become. By twisting the plurality of strands 1, spiral valleys (tip pockets) formed between the strands become passages for the machining liquid.

In order to make the substantial diameter D of the wire tool at the time of slicing work the same as that of a conventional core wire made of a single wire, the diameter of the wire is 1/2, 3 or 2 twists. It must be 1 / 2.15. Accordingly, the cross-sectional area of the core wire is 0.5 and 0.65, respectively, which is naturally smaller than that of a single strand. However, as the wire diameter of a piano wire becomes smaller, the tensile strength per unit area becomes larger. Is small and there is no concentration of stress, so that the tensile strength is rather large as compared with a single strand having a grooved surface.

Further, the wire is twisted during the slicing process to generate shear stress. However, since the wire diameter is small, the value of the shear stress caused by the twist is small, and the durability at this point is greatly improved. When the plurality of strands 1 are twisted, it is more preferable to twist the strands without giving twists to the strands themselves, because the strands do not generate residual stress in the strands.

[0013]

FIG. 3 is a diagram showing an outline of an apparatus for manufacturing a brittle material cutting wire tool 7 (hereinafter referred to as a stranded wire tool) according to the present invention. The apparatus of the illustrated embodiment includes a stranded wire device 11, an abrasive electrodeposition device 31, and a winding device 51.
It consists of two devices. In the stranded wire device 11, the stranded wire 6 serving as a core wire is produced, and diamond abrasive grains are electrodeposited on the stranded wire by nickel plating in an abrasive electrodeposition device 31. Then, the produced stranded wire tool 7 is wound around the bobbin by the winding device 51. By changing the rotation speed of the bobbin support arm of the twisting device 11 and the winding speed of the bobbin 52 of the winding device 51, a twisted wire tool having an arbitrary twist pitch can be manufactured.

FIG. 4 is a perspective view showing the twisting device. A rotating arm 15 is attached to the tip of a main shaft 14 rotatably supported by bearings 13 and 13 mounted on the base 12, and the main shaft 14 and the main shaft 14 are positioned at equal distances from the center of the main shaft at both ends of the rotating arm. A bobbin holder 16 is mounted so as to be freely rotatable about a parallel axis. Bobbin holder 16
, A bobbin 18 around which a piano wire 1 serving as a strand is wound around an axis orthogonal to the main shaft 14 is rotatably mounted. In FIG. 4, one of the bobbin and the bobbin holder and one side of the rotary arm are shown in phantom lines to show the gear train behind them.

Behind the rotating arm 15, a sun gear 19 is fixedly mounted on the base 12 so as to be coaxial with the main shaft 14, and an intermediate gear 20 rotatably mounted on the rotating arm 15 is provided with a sun gear 19. The planetary gear 21 fixed to the bobbin holder 16 meshes with the intermediate gear. A pulley 22 is mounted on the rear end of the main shaft 14, and a motor 24 is connected via a belt 23.

When the piano wire 1 is drawn from the two bobbins 18 while rotating the main shaft 14 with the motor 24, the two piano wires are twisted by the revolving motion of the two bobbins. On the other hand, by the action of the sun gear 19, the intermediate gear 20, and the planetary gear 21, each bobbin 18 is
5, the bobbin 18 does not rotate on its own in the direction opposite to the rotation direction of the main shaft 14 at the same speed. That is, the bobbin 18 always keeps the same direction, so that the two wires pulled out of the bobbin are twisted without twisting each wire itself.

The stranded wire 6 thus manufactured
Is contacted with the cathode electrode 32, the surface of the wire is degreased through an acetone tank 33, the surface is activated through a 10% hydrochloric acid tank 34, and is sent to an electrodeposition plating tank 35.

Activated twisted wire 6 whose surface is degreased and activated
Are nickel plates 37 arranged on both sides of the electrodeposition plating tank 35.
With nickel as the anode and the stranded wire 6 itself as the cathode. In the first tank 35a, only the nickel is pre-plated on the stranded wire 6 to ensure the adhesion between the plating layer 4 and the piano wire surface.

Next, the stranded wire 6 (FIG. 6 shows a main part of the second tank 35b of the electrodeposition plating tank).
It is led to 35 g of an abrasive grain tank provided in 5b. The diamond abrasive grains 3 are filled in the space in the abrasive grain tank 35 g provided in the plating solution. The wall plate 40 of the abrasive tank 35g has a diameter of 1
A hole 41 having a diameter of about 0 mm is formed, and a Teflon film 42 is formed on the hole 41 to prevent outflow of the diamond abrasive grains 3 and allow inflow of a plating solution. Further, in order to promote the inflow of the plating solution into the abrasive tank, a plating liquid suction pipe 43 is provided at a lower portion of the abrasive tank, and is constantly sucked by a liquid feed pump (not shown). A plate-shaped weight 38 is inserted into the upper portion of the abrasive grain tank 35g so that a cavity is not formed in the abrasive grain tank 35g due to the decrease in diamond abrasive grains caused by the implantation of the abrasive grains on the stranded wire 6. Is added.

In the abrasive tank 35 g, the diamond abrasive grains in contact with the surface of the stranded wire 6 land on the surface of the stranded wire 6 together with the plating layer 4. After that, the stranded wire 6 is guided to the third tank 35c, and only nickel plating is performed to further bury and fix the diamond abrasive grains with shallow landing on the wire surface.

The stranded wire tool 7 having the diamond abrasive grains electrodeposited on the surface in this way is washed through a washing tank 36 and then wound up on a bobbin 52 by a winding device 51.

FIG. 5 is a perspective view of the winding device. The winding bobbin 52 is driven by a motor 55 via a timing belt 35 and a timing pulley 54. Further, the rotational force of the winding bobbin 52 is transmitted to the ratchet pawl 56 via a joint having a crank mechanism, and causes the ratchet pawl 56 to reciprocate to rotate the ratchet wheel 57 intermittently. The ratchet wheel 57 rotates by one pitch every time the winding bobbin 52 makes one rotation. This rotational motion is transmitted to the cylindrical cam 60 via the gears 58 and 59. In front of the winding bobbin 52, a guide pulley 61 for guiding the stranded wire tool 7,
A slider 62 to which 61 is attached is slidably provided in parallel with the bobbin axis, and a pin 63 protruding downward is pressed against the cylindrical cam 60 by the restoring force of a coil spring 64. The slider 62 reciprocates with the rotation of the take-up bobbin 52, and the wire tool on which the abrasive grains are electrodeposited is aligned and wound around the take-up bobbin 52.

Next, the results of a cutting test of the stranded wire tool manufactured as described above will be described. The apparatus subjected to the cutting test is a reciprocating type cutting apparatus schematically shown in FIG. 7 and includes a winding and feeding section 71 of the stranded wire tool 7, a cutting section 72, and a wire tension adjusting section 73. I have. One end of the stranded wire tool 7 is wound around one side of the double drum 74, passes through the tension adjusting section 73 and the cutting section 72 via the guide pulley 75, and the other end is on the opposite side of the double drum 74. It is wound around. The duplex drum 74 is installed at an inclination of 18 degrees, so that when the stranded wire tool 7 is sent out and wound up, the adjacent stranded wire tools overlap each other, and the stranded wire tool is damaged. Is prevented.

The double drum 74 includes a stepping motor 76
When the wire tool 7 is rotated forward and backward, the stranded wire tool 7 reciprocates and cuts the workpiece (brittle material) 77 in the cutting portion 72. The tension of the wire tool 7 is kept constant in a tension adjusting section 73 constituted by a torque motor 78.

FIG. 10 shows a cutting process performed by using a stranded wire tool prepared in three stages of a wire diameter of 0.1 mmφ and a twist pitch of 2, 5, and 10 mm until the number of cuts reaches 30 times. The behavior of the cutting efficiency obtained at this time was shown in comparison with the cutting efficiency of a conventional single-strand wire tool. In the figure, a black circle is a stranded wire tool with a twist pitch of 2 mm, a black triangle is a stranded wire tool with a twist pitch of 5 mm, a black square is a stranded wire tool with a twist pitch of 10 mm, and a white circle is a single wire with a strand diameter of 0.2 mmφ. A wire tool. The stranded wire tool showed higher cutting efficiency than the single strand wire tool at any pitch, especially as the pitch became smaller.

The reason will be described with reference to machining model diagrams shown in FIGS. In the case of the single strand wire tool of FIG.
The working fluid supplied to the working part can flow only from between the abrasive grains on the surface of the wire tool, and the amount of working fluid supplied to the working part is considered to be extremely small compared to the amount actually supplied. . As a result, not only is it difficult to dissipate the grinding heat, but also because the chips are poorly discharged, the chips tend to remain around the abrasive grains, causing the abrasive grains to be clogged and cutting performance of the wire tool. Deteriorates.

On the other hand, in the case of the stranded wire tool shown in FIG.
Since the stranded wire is used as the core wire, valleys that become chip pockets are formed on the surface of the wire tool, which facilitates the flow of machining fluid into the machining area and discharges chips quickly, so that the abrasive grains Deterioration of cutting performance due to clogging can be prevented. Since the cutting efficiency becomes higher as the twist pitch becomes smaller, it is considered that the action of the chip pocket improves as the pitch becomes smaller, and the chip discharging effect becomes more remarkable. From this, it is clear that the use of a stranded wire tool not only can significantly improve the cutting performance than the conventional single-strand wire tool, but also can extend the life. Was.

[Brief description of the drawings]

FIG. 1 is a plan view of a stranded wire tool of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a schematic diagram of an apparatus for manufacturing a wire tool.

FIG. 4 is a perspective view of a twisted wire device in a manufacturing apparatus.

FIG. 5 is a perspective view of a winding device in the manufacturing apparatus.

FIG. 6 is a perspective view of a main part of a second tank of an electrodeposition plating tank in the manufacturing apparatus.

FIG. 7 is a perspective view of a cutting apparatus.

FIG. 8 is a schematic diagram when processing is performed using a conventional wire tool.

FIG. 9 is a schematic diagram when processing is performed using a stranded wire tool.

FIG. 10 is a graph of the number of cuts and cutting efficiency.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Element wire 2 Core wire 3 Abrasive grain 4 Nickel plating layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kentaro Ota 7-1 Ogigaoka, Nonoichi-machi, Ishikawa-gun, Ishikawa Prefecture Inside Kanazawa Institute of Technology

Claims (4)

[Claims] 1. A wire tool for cutting brittle material, wherein abrasive grains are uniformly electrodeposited on a surface of a core wire formed by twisting a plurality of strands. 2. The brittle material cutting wire according to claim 1, wherein the number of the wires forming the core wire is 2 or 3, the abrasive grains are diamond abrasive grains, and the electrodeposition plating layer is a nickel plating layer. tool. 3. A step of twisting two or three strands to form a core, a step of cleaning the surface of the twisted strand and electrodepositing abrasive grains on the exposed surface, Winding a core wire on which abrasive grains have been electrodeposited, the method comprising the steps of: 4. A wire tool for cutting brittle material according to claim 3, wherein a plurality of strands forming a core wire are supplied from a plurality of wire bobbins which revolve around the same axis and do not rotate and are twisted. Manufacturing method.