JP4386814B2 - Resin bond wire saw - Google Patents

Description

  The present invention relates to a resin bond wire saw in which abrasive grains are bonded with resin around a core wire.

  In the field of manufacturing various semiconductor devices, with the large diameter of silicon wafers, the cutting method from a silicon ingot is being shifted to a wire saw cutting method that can easily cope with the large diameter. As this wire saw, a fixed abrasive type wire saw in which abrasive grains such as WA, GC, diamond, and cBN are fixed to the peripheral surface of a core wire is used.

  As this fixed abrasive type wire saw, there are an electrodeposited wire saw for fixing abrasive grains by electrodeposition and a resin bond wire saw for fixing abrasive grains using a resin as a binder. Manufacturing problems that it is practically impossible to electrodeposit abrasive grains on long core wires as long as one hundred kilometers, and usage problems that break torsional strength and bending strength make it easy to break during processing Resin bond wire saws have been developed as an improvement of these drawbacks, and resin bond wire saws are now becoming the mainstream of wire saws.

In the multi-cutting process using a resin bond wire saw, it is necessary to accurately cut with a stable processing efficiency. For this purpose, it is necessary to keep the number of working abrasive grains on the surface of the wire saw as constant as possible. However, the grain size of the abrasive grains is not actually constant but usually has a predetermined distribution, and it is difficult to align the abrasive grain tips. In order to align the tips of the abrasive grains, it is effective to sink the abrasive grains in the resin. For this purpose, it is effective to provide a resin-only layer between the abrasive grain layer and the core wire.
An example in which a resin-only layer is provided between a core wire and an abrasive layer is described in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5.

JP 2000-71161 A Japanese Patent No. 3390686 JP 2000-246542 A Japanese Patent No. 3362015 JP 2001-79775 A

However, both of these are those in which an adhesive layer is provided between the core wire and the abrasive grain layer to increase the adhesive strength. Even if the abrasive grains are arranged using these components, the tip of the abrasive grain tip The height cannot be aligned.
The present invention has been made in view of such circumstances, and provides a resin bond wire saw capable of accurately cutting while maintaining a stable processing efficiency by aligning the tips of abrasive grains. Objective.

In order to solve the above problems, the present invention provides a resin bond wire saw in which abrasive grains are fixed in a single layer using a resin as a binder on the surface of a core wire, and a buffer layer made of only resin is provided around the core wire, An abrasive layer is formed on the outer periphery of the buffer layer by bonding the abrasive grains with a binder not added with filler or a binder added with a soft filler that does not inhibit the sinking of the abrasive grains. a is the elastic modulus of the wood is 1500MPa or less, the elastic modulus of the buffer layer is Ri der 0.4 times the elastic modulus of the binder of the abrasive layer, and characterized that you have uniform abrasive tip Resin bond wire saw.
By providing the buffer layer having such an elastic modulus, the abrasive grains sink into the buffer layer during grinding, and even when abrasive grains having different particle diameters are used, the tips of the abrasive grains can be aligned.

Also, if the elastic modulus of the binder of the abrasive layer exceeds 1500 MPa, the flexibility of the wire saw becomes poor, the resin peels off at the contact position with the pulley and the contact portion with the work material, and the abrasive grains fall off. Since it becomes easy to do, it is not preferable.

  In the present invention, no metal filler is added to the abrasive layer. This is because when the metal filler is added, the sinking of the abrasive grains is hindered.

  In the present invention, the binder of the abrasive layer is made of a photosensitive resin. Since the photosensitive resin cures instantaneously, the position of the abrasive grains hardly changes during the curing process, and the positional deviation of the abrasive grains hardly occurs.

In the present invention, the thickness of the buffer layer is 2 μm or more and 5 μm or less.
If the thickness of the buffer layer is less than 2 μm, the buffer layer is too thin and the abrasive grains cannot sink sufficiently, so that the tips of the abrasive grains are difficult to align and the surface roughness of the work material increases. When the thickness of the buffer layer is 2 μm or more, the surface roughness of the work material is improved. However, when the thickness exceeds 5 μm, the surface roughness is almost constant.

  ADVANTAGE OF THE INVENTION According to this invention, the resin bond wire saw which can arrange | equalize the front-end | tip of an abrasive grain and can maintain a stable processing efficiency and can perform a cutting process accurately can be implement | achieved.

Hereinafter, the resin bond wire saw of this invention is demonstrated based on the embodiment.
In FIG. 1, the structure of the resin bond wire saw which concerns on embodiment of this invention is shown. In FIG. 1, a resin bond wire saw 1 is provided with a buffer layer 3 made of resin only around a core wire 2 made of a piano wire or the like, and abrasive grains 4 bonded to the outer periphery of the buffer layer 3 with a binder 5. A grain layer 6 is formed. The buffer layer 3 has a thickness of about 2 to 5 μm and an elastic modulus of 1000 MPa or less. Moreover, the binder 5 of the abrasive layer 6 is formed of a photosensitive resin and has an elastic modulus of 1500 MPa or less. In neither the buffer layer 3 nor the abrasive layer 6, no metal filler is added.

Based on FIG. 2, in the resin bond wire saw of the present invention, a method for aligning abrasive grain tips will be described in comparison with a conventional one. 2A is a conventional resin bond wire saw in which the buffer layer 3 is not formed, and FIG. 2B is a resin bond wire saw according to an embodiment of the present invention.
In the conventional resin bond wire saw shown in FIG. 2A, since the buffer layer 3 is not formed, the bottom of the abrasive grains 4 cannot directly sink into contact with the core wire 2. The tips cannot be aligned. On the other hand, in the resin bond wire saw of the present invention shown in FIG. 2B, since the buffer layer 3 is formed, the abrasive grains 4 having a large particle size may sink into the buffer layer 3 during grinding. Even if the abrasive grains 4 having different particle diameters are arranged, the tips of the abrasive grains 4 can be aligned.

  FIG. 2C shows a state of a load applied to the abrasive grains during processing. The abrasive grain 4 is subjected to a load Fn in the cutting direction (normal direction of the wire saw) and a load Ft in the traveling direction of the wire saw (tangential direction of the wire saw). As a result, the abrasive grain 4 is applied to the axis of the wire saw. On the other hand, a resultant force in an oblique direction acts.

  When the elastic modulus of the binder 5 of the abrasive layer 6 is E1 and the elastic modulus of the buffer layer 3 is E2, E1 ≧ E2, that is, the elastic modulus of the buffer layer 3 is the elasticity of the binder 5 of the abrasive layer 6. By making the ratio or less, the abrasive grains 4 can be easily subducted, and the tips of the abrasive grains 4 can be aligned. Furthermore, by setting the elastic modulus of the buffer layer 3 to 0.7 times or less of the elastic modulus of the binder 5 of the abrasive layer 6, the abrasive particles 4 can be effectively subducted.

The reason for the elastic modulus of the binder 5 of the abrasive grain layer 6 less 1500 MPa, will be described with reference to FIG. In the processing by the wire saw, the component Fn in the normal direction of the load is small as compared with the general processing by other methods, and in order to sink the abrasive grains, the elastic modulus of the bonding material 5 of the abrasive layer 6 is 1500 MPa or less. It is good to do.

  Further, the wire saw is set to the wire guide 10 via a number of pulleys, and during the machining, the contact portion 12 with the work material 11 is bent and the cutting proceeds. Therefore, the wire saw needs to be deformed flexibly with respect to this bending to absorb the load. When the elastic modulus of the binding material 5 of the abrasive grain layer 6 exceeds 1500 MPa, the flexibility of the wire saw becomes poor, and the resin is peeled off at the contact position with the pulley or at the contact portion 12 with the work material 11. Will drop, and the processing efficiency and processing accuracy will decrease. From such circumstances, the elastic modulus of the binder 5 of the abrasive layer 6 is set to 1500 MPa or less.

  In the resin bond wire saw of the present invention, the metal filler is not added, but this is because, as shown in FIG. 4, if the metal filler 13 is added, the sinking of the abrasive grains 4 is inhibited. . However, it is possible to add a soft filler that does not inhibit the sinking of the abrasive grains 4.

  The bonding material 5 of the abrasive grain layer 6 is formed of a photosensitive resin, and thus the bonding material 5 of the abrasive grain layer 6 can be instantaneously cured. FIG. 5 shows a comparison between the case where the photosensitive resin is used and the case where the thermosetting resin is used. The thermosetting property of (b) is compared with the case of forming the abrasive layer shown in (a). In the case of resin, the abrasive grains 4 are easy to move due to shrinkage at the time of curing, and it is difficult to align the tips of the abrasive grains 4. However, in the case of the photosensitive resin (c), the abrasive grains 4 are cured instantaneously. The position hardly changes and the tips of the abrasive grains 4 are easily aligned. Moreover, since the hardening time of liquid resin can be shortened, production efficiency can be improved.

  The formation of the abrasive layer 6 can be performed by a known method. For example, the core wire 2 on which the buffer layer 3 is formed is passed through a mixture of abrasive grains 4 and a liquid resin contained in a container so that the surface of the buffer layer 3 is coated with the mixture of the abrasive grains 4 and the liquid resin. A wire saw is manufactured by passing the core wire 2 through a die having a predetermined inner diameter, curing the liquid resin after passing through the die, and fixing the abrasive grains 4 to the core wire 2.

  The buffer layer 3 can be formed by the same method as the method for forming the abrasive layer 6. Pass the liquid resin contained in the container to coat the surface of the core wire 2 with the liquid resin, pass the core wire 2 in this state through a die having a predetermined inner diameter, and cure the liquid resin after passing through the die to form the core wire. The buffer layer 3 is formed on 2. In addition, since resin of the buffer layer 3 is not limited other than an elastic modulus, a photosensitive resin, a thermosetting resin, and a thermoplastic resin can be used.

  In FIG. 6, the elastic modulus of the binder 5 of the abrasive layer 6 is fixed to 1500 MPa, and the ratio between the elastic modulus of the buffer layer 3 and the elastic modulus of the binder 5 of the abrasive layer 6 is changed, and FIG. As shown, the result of measuring the displacement in the normal direction of the abrasive grain tip by applying a load in the normal / tangential direction to the abrasive grain tip is shown. Ratio of elastic modulus (elastic modulus of buffer layer / elastic modulus of binder of abrasive layer)> 0.7 is almost the same as 1.0, whereas elastic modulus ratio ≦ 0 In the case of .7, the amount of displacement in the normal direction increases. Further, when the elastic modulus ratio ≦ 0.4, the amount of displacement increases rapidly, and the effect of the sinking of the abrasive grains 4 is further increased.

FIG. 8 shows the results of measuring the surface roughness of the work material by performing a cutting test while changing the ratio between the elastic modulus of the buffer layer 3 and the elastic modulus of the bonding material 5 of the abrasive layer 6. The test conditions are as follows.
Work Material Single Crystal Silicon Wire Wire Speed 300m / min
Grinding fluid Water-soluble grinding fluid According to the test results, the surface roughness of the work material is stable at a good value when the ratio of elastic modulus ≦ 0.7.
From the above results, the elastic modulus of the buffer layer 3 is preferably 0.7 times or less, more preferably 0.4 times or less than the elastic modulus of the binder 5 of the abrasive layer 6.

  FIG. 9 shows the results of examining the number of cracks generated by conducting a winding test while changing the elastic modulus of the binder 5 of the abrasive layer 6. The test was performed by winding a wire saw 15 times around a round bar having a diameter of 2.0 mm, observing the surface of 10 wire saws located at the center, and counting the number of cracks. As shown in FIG. 9, the number of cracks is large when the elastic modulus of the binder 5 of the abrasive layer 6 is 1800 MPa, whereas the number of cracks is low when the elastic modulus of the binder 5 of the abrasive layer 6 is 1500 MPa or less. There were few cracks at 1000 MPa or less.

FIG. 10 shows a result of measuring the peeling length of the abrasive layer 6 by performing a cutting test while changing the elastic modulus of the binder 5 of the abrasive layer 6. The test conditions are as follows.
Work Material Single Crystal Silicon Wire Wire Speed 300m / min
Grinding fluid Water-soluble grinding fluid According to the test results, when the elastic modulus of the binder 5 of the abrasive layer 6 is 1500 MPa or less, the peeling length of the abrasive layer 6 is reduced.
From the above results, the elastic modulus of the binder 5 of the abrasive layer 6 is preferably 1500 MPa or less, and more preferably 1000 MPa or less.

FIG. 11 shows a result of measuring the surface roughness of the work material by performing a cutting test while changing the thickness of the buffer layer 3. The test conditions are as follows.
Work Material Single Crystal Silicon Wire Wire Speed 300m / min
Grinding fluid Water-soluble grinding fluid

  As shown in FIG. 11, if the thickness of the buffer layer 3 is less than 2 μm, the abrasive grains 4 cannot sink sufficiently, so that the tips of the abrasive grains are difficult to align and the surface roughness increases. When the thickness of the buffer layer 3 is 2 μm or less, the surface roughness is improved, but when it exceeds 5 μm, the surface becomes almost constant. Accordingly, the thickness of the buffer layer 3 is preferably 2 μm or more and 5 μm or less.

  INDUSTRIAL APPLICABILITY The present invention can be used as a resin bond wire saw capable of cutting with high precision while maintaining a stable processing efficiency by aligning the tips of abrasive grains.

It is a figure which shows the structure of the resin bond wire saw which concerns on embodiment of this invention. In the resin bond wire saw of this invention, it is a figure explaining the method of aligning an abrasive grain front-end | tip. It is a figure explaining the reason which is making the elasticity modulus of the binder of an abrasive grain layer into 1500 Mpa or less. It is a figure explaining the case where a metal filler is added. It is a figure which compares and demonstrates the case where a photosensitive resin is used, and the case where a thermosetting resin is used. The elastic modulus of the buffer layer binder is fixed at 1500 MPa, and the ratio of the elastic modulus of the buffer layer to that of the abrasive layer is changed to apply a load in the normal / tangential direction to the abrasive grain tip. It is a figure which shows the result of having measured the displacement of the normal direction of the abrasive grain tip. It is a figure which shows the direction of the load concerning an abrasive grain front-end | tip. It is a figure which shows the result of having performed the cutting test by changing the ratio of the elasticity modulus of a buffer layer, and the elasticity modulus of the binder of an abrasive grain layer, and measuring the surface roughness of a workpiece. It is a figure which shows the result of having investigated the number of the cracks which performed the winding test by changing the elasticity modulus of the binder of an abrasive grain layer, and produced | generated. It is a figure which shows the result of having performed the cutting test by changing the elasticity modulus of the binder of an abrasive grain layer, and measuring the peeling length of an abrasive grain layer. It is a figure which shows the result of having performed the cutting test by changing the thickness of a buffer layer, and measuring the surface roughness of a workpiece.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin bond wire saw 2 Core wire 3 Buffer layer 4 Abrasive grain 5 Binder 6 Abrasive layer 10 Wire guide 11 Work material 12 Contact part 13 Metal filler

Claims (3)

In a resin bond wire saw in which abrasive grains are fixed as a single layer using resin as a binder on the surface of the core wire, a buffer layer made only of resin is provided around the core wire, and filler is added to the outer periphery of the buffer layer. An abrasive layer bonded with a binder that is not bonded or a binder added with a soft filler that does not hinder sinking of the abrasive grains is formed, and the elastic modulus of the binder of the abrasive layer is 1500 MPa or less, and the buffer der 0.4 times or less the modulus elasticity of the binder of the abrasive grain layer of the layer is, resin bond wire saw characterized that you have uniform abrasive tip.   2. The resin bond wire saw according to claim 1, wherein the binder of the abrasive layer is made of a photosensitive resin.   The resin bond wire saw according to claim 1 or 2, wherein the buffer layer has a thickness of 2 µm or more and 5 µm or less.

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