JP3604319B2 - Resin bond wire saw - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixed abrasive type wire saw using a resin bond, and more particularly to a resin bond wire saw capable of maintaining good sharpness from the beginning to the end of processing.
[0002]
[Prior art]
In the field of manufacturing various semiconductor devices, performance has been improved by miniaturization of wiring patterns.However, miniaturization of wiring patterns alone cannot keep up with multi-functionality. ing. With the increase in the size of such chips, silicon wafers with large diameters have been used from the viewpoint of improving the yield, and the cutting method from the silicon ingot, which is the preceding process, has also been changed from the conventional inner peripheral blade cutting method. The transition to the wire saw cut method, which can easily accommodate large diameters, is being made.
[0003]
One of the wire saw cutting methods that has been mainly performed in the past is a loose abrasive method using a slurry. In this loose abrasive method, a piano wire or ultra-high strength alloy wire is run in strong contact with the silicon ingot, and the free wire such as WA or GC is applied to the portion where the piano wire or ultra-high strength alloy wire is in contact. Cutting is performed while pouring lubricating oil containing particles. However, it is said that there is a limit to the cutting efficiency due to the deterioration of the working environment and the contamination of the work due to the scattering of the lubricating oil, and the inability to control the depth of penetration of the abrasive grains into the work material to be uniform. I have.
[0004]
On the other hand, in recent years, a fixed abrasive method using a wire saw in which abrasive grains such as WA, GC, diamond, and CBN are fixed to the peripheral surface of a core wire has been proposed. As a wire saw used in the fixed abrasive method, an electrodeposited wire saw for fixing the abrasive grains by electrodeposition and a resin bond wire saw for fixing the abrasive grains using a resin (resin) as a binder are known. Even with these electrodeposited wire saws and resin bond wire saws, cutting by abrasive grains is possible by running while strongly contacting the workpiece similarly to the loose abrasive method.
[0005]
By the way, an electrodeposited wire saw spends much time in the plating process of electrodepositing abrasive grains and it is difficult to make it longer, and it has a low breaking torsional strength and a low bending strength, so it is easy to break during processing. Usage problems have long been pointed out. Thus, there is a history that a resin bond wire saw has been developed as an improvement over such a drawback of the electrodeposited wire saw.
[0006]
As such a resin bond wire saw, for example, there is a resin bond wire saw described in JP-A-10-138114. The resin bond wire saw described in this publication has a configuration in which a high tensile strength metal is used as a core wire, and a polyamideimide resin is used as a binder and abrasive grains are dispersed and contained in the core wire to coat the core wire.
[0007]
[Problems to be solved by the invention]
According to such a resin bond wire saw, the problem of the electrodeposited wire saw can be solved, but on the other hand, since the entire abrasive grains are covered with the resin, the amount of the abrasive grains protruding is small, and poor sharpness in the initial stage of cutting becomes a problem. Has become. As one of the methods for solving this problem, dressing by dressing can be considered as in the case of a general grindstone. However, since the abrasive layer of the wire saw has a thickness of only about several tens of μm, the dressing operation is not easy.
[0008]
On the other hand, as described in JP-A-11-28654, when a wire saw is wound around a groove roller to cut a silicon wafer, a dressing stone is pressed against the wire saw between the groove rollers to dress the wire saw. A method has been proposed. However, in the method of dressing a wire saw by pressing such dressing stones, although clogging is reduced to some extent due to the sharpening effect, a load is applied to the wire at the time of dressing, and the wire may be damaged. There is a risk of disconnection.
[0009]
An object of the present invention is to provide a resin bond wire saw that improves sharpness at the beginning of cutting without performing dressing, maintains the sharpness over a long period of time, and is free from a risk of disconnection.
[0010]
[Means for Solving the Problems]
The present invention provides a resin bond wire saw in which abrasive particles are fixed to a surface of a wire with a resin as a binder, using a photocurable resin as the resin, and forming a low-hardness uncured layer on the surface layer of the abrasive layer. It is characterized by having done.
[0011]
By forming the low-hardness unhardened layer on the surface layer of the abrasive layer, the low-hardness unhardened layer is deleted due to the resistance in the initial stage of processing, and the abrasive grain tip becomes a surface of the abrasive layer protruding by about several μm. As a result, the sharpness of the wire saw at the initial stage of processing is improved, and further, by holding the abrasive grains by the high-hardness resin layer below the abrasive layer, it is possible to maintain the excellent sharpness until the end of processing. Further, unlike the conventional method using dressing stones for dressing, there is no fear of peeling of the abrasive grain layer due to wire breakage or scratch of the abrasive grain layer.
[0012]
In order to form a low-hardness uncured layer on the surface layer of the abrasive layer, the properties of the photocurable resin in curing are used. The photo-curable resin is generally used in the atmosphere, but when the curing reaction is performed by light irradiation, the curing reaction of the resin layer in contact with the atmosphere has a property that does not easily proceed, and is completely cured. Requires higher energy. The reason that the curing reaction of the resin surface layer that is in contact with the atmosphere is difficult to proceed is considered to be that the radical generated from the photopolymerization initiator is inhibited by the curing reaction that reacts with oxygen in the atmosphere. Higher energy is required to generate an amount of radicals that breaks reaction inhibition. Therefore, when curing by light irradiation, an uncured low-hardness layer is formed on the resin layer by performing a curing reaction using light energy such that the inside of the resin is completely cured but the surface layer is not completely cured. Can be.
[0013]
As the photocurable resin, a photosensitive resin having a functional group excited by a photopolymerization initiator and polymerizing by a photochemical reaction can be used. Such resins include, for example, those having a π bond such as C = C, those having an epoxy, and the like. It becomes a resin having properties. In addition, the photo-curable resin auxiliary additive includes a curing accelerator such as an anaerobic curing agent that promotes a polymerization reaction by blocking oxygen or a heat curing agent that exhibits the same effect as described above by heat, and Stabilizers that stabilize resin properties before curing and polymers and copolymerizable monomers that do not inhibit photochemical reactions can be used.If they do not inhibit photochemical reactions, they change the properties of the cured product. For the purpose, metal powders such as Cu, Ni, Co and Fe, non-metallic powders such as C and SiO ₂ , inorganic salts such as MgSO ₄ , and general abrasive grains such as GC and WA are added as filler material. Is also possible.
[0014]
The amount of light irradiation that does not completely cure the surface layer of the resin during curing by light irradiation varies depending on the type of resin used, the size of the wire saw, and the like. It is desirable to obtain the type, illuminance, distance, feed speed of the wire saw core wire, and the like.
[0015]
The method of manufacturing a resin bond wire saw according to the present invention is basically the same as the conventional method of manufacturing a resin bond wire saw except for the adjustment of the light irradiation amount, and includes a brass-plated piano wire or a special alloy steel. While sending core wire such as wire and ultra-high-strength alloy wire at a fixed pitch, it is passed through a coating tank containing a mixture of liquid photo-curable resin and abrasive grains such as diamond abrasive grains and CBN abrasive grains, and then liquid is applied to the core wire. A resin-bonded wire saw is manufactured by coating a mixture of resin and abrasive grains and then passing the mixture through a resin curing device such as an ultraviolet irradiation device to cure the liquid resin and fix the abrasive particles to the core wire.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a partial front view of a wire saw according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view taken along line AA of FIG.
[0017]
The wire saw according to the present embodiment is obtained by mixing a filler wire with an acrylate resin to which a photoradical generator is added so that the core wire 1 of a piano wire having a wire diameter of 0.16 mm and the finished outer diameter of the core wire 1 is 0.22 mm. The abrasive layer 2 is formed by fixing diamond abrasive grains 4 having an average particle diameter of 30 μm by the bond layer 3.
[0018]
The acrylate resin used in the present embodiment completely cures to the surface layer when reacted with energy of 150 mW / cm ² for 15 seconds. However, when reacted with energy of 100 mW / cm ² for 20 seconds, the abrasive layer having a thickness of 30 μm is formed. The uncured layer can be formed up to about 5 μm from the surface layer. Here, the uncured layer refers to a liquid or gel resin layer in which the curing reaction has not progressed and has not been polymerized.
[0019]
As shown in FIG. 2, in the abrasive layer 2 after manufacturing (before use), most of the diamond abrasive grains 4 are buried in the bond layer 3, and very few abrasive grains protrude from the bond layer 3. is there. In a conventional wire saw, sharpness during cutting is not stable in a state where such protruding abrasive grains are small, and dressing is necessary from the beginning of processing to stabilize the cutting. However, in the wire saw of the present embodiment, the bond layer By using a photo-curable resin to which a photo-radical generator is added as the resin of No. 3 and irradiating ultraviolet rays under conditions that the surface layer 3a of the bond layer 3 is not completely cured during the curing reaction, the surface layer 3a becomes an inner layer portion. Since the hardness is lower than that of 3b, the bond layer 3 as shown in FIG. 2 before use comes into contact with the workpiece and, at the same time, the bond of the surface layer 3a having low hardness is mechanically deleted. As shown in FIG. 3, the tips of the diamond abrasive grains 4 protrude. As a result, the wire saw exhibits good sharpness from the beginning of processing, and each time processing is performed, the removal of the resin of the surface layer is repeated, so that a substantial dressing operation is performed, without dressing until the end of processing. , Good sharpness can be maintained.
[0020]
As described above, since the wire saw of the present embodiment does not need to be dressed from the beginning to the end of processing, there is no risk of disconnection caused by scratching the core wire 1 and cracks are generated in the bond layer 3. Since there is no abrasive grain, the abrasive grain holding power does not decrease.
[0021]
In order to confirm the effects of the present invention, the wire saw of the above embodiment (inventive product), a wire saw completely cured to the surface layer of the bond layer (comparative product), and a conventional wire saw using a phenol resin as a resin (conventional product) ) Was used for a cutting test.
〔Test condition〕
Cutting device: Single wire cutting device Wire speed: 400m / min on average
Wire tension: 19.6N
Workpiece: Silicon ingot [0022]
FIG. 4 shows the test results. FIG. 4 is a diagram showing the relationship between the total processing amount and the sharpness. The vertical axis represents the cutting speed (index), and the horizontal axis represents the integrated deletion amount in terms of the number of cut ingots. As can be seen from the figure, in the initial stage of processing, the invention product shows about twice as good sharpness as the conventional product, and the difference becomes remarkable when the processing amount is further increased, and when the 100 pieces are processed, the difference is about 4 times. Was seen. From these results, it was confirmed that the inventive product had better sharpness from the beginning of processing than the conventional product, and that the sharpness could be maintained for a long time. The comparative product had sharpness not much different from the conventional product.
[0023]
【The invention's effect】
(1) By using a photocurable resin as a binder and forming a low-hardness uncured layer on the surface layer of the abrasive layer, the low-hardness uncured layer is removed due to the resistance at the initial stage of processing, and the abrasive grains are removed. The tip is projected and a substantial sharpening operation is performed, so that good sharpness can be maintained without dressing until the end of processing.
[0024]
(2) Since there is no need to perform dressing from the beginning to the end of processing, there is no risk of disconnection caused by damage to the core wire, and no cracks are generated in the abrasive layer, so that the abrasive holding force is low. It does not drop.
[Brief description of the drawings]
FIG. 1 is a partial front view of a wire saw according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view taken along line AA of FIG.
FIG. 3 is a diagram showing a cross section of the wire saw at the time of cutting.
FIG. 4 is a diagram showing a cutting test result.
[Explanation of symbols]
Reference Signs List 1 core wire 2 abrasive layer 3 bond layer 3a surface layer 3b inner layer 4 diamond abrasive

Claims (1)

In a resin bond wire saw in which abrasive particles are fixed to a surface of a wire using a resin as a binder, a light-hardening type resin is used as the resin, and a low-hardness uncured layer is formed on a surface portion of the abrasive layer. Resin bond wire saw.

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