JPH10337669A - Grinding wheel and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the density and to secure the strength by increasing the dispersing property and the conformity of the abrasive grains, and to allow to suppress a grinding burn, a blinding, a scratch, and the like, in the grinding, the rubbing, the polishing, and the like. SOLUTION: In this grinding wheel, the whole body is composed only of sintered bodies of minute inorganic abrasive grains 0.02 to 2 μm, and no binder is added practically. As the manufacturing method of this grinding wheel, at first, a slurry is manufactured by adding the cesium oxide powder the alumina power, the water, and the polycarboxilic acid type ammonium salt as a dispersing agent. After the obtained slurry is molded into a specific form by a coating molding, a pressurizing molding, or the like, it is dried and baked. In this case, it is desirable to control the conditions of the abrasive grains, the dispersing agent, the water volume, and the like, depending on the object using the grinding wheel. Furthermore, an inorganic grain, a carbon grain, an inorganic solvent, and the like may be added as necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to various types of grinding,
The present invention relates to a grindstone intended for use as an object to be polished or polished, and a method for producing the same.

[0002]

2. Description of the Related Art For polishing or polishing the surface of a silicon wafer or the like used as a semiconductor material, a method using so-called free abrasive grains, which supplies inorganic abrasive grains themselves, has been used. For other grinding and polishing, a method using a fixed whetstone in which inorganic abrasive grains are fixed with a binder is used. For example, a vitrified grindstone obtained by firing inorganic abrasive grains such as fused alumina and silicon carbide at 1300 ° C. or less with an inorganic binder such as feldspar, A diamond or cubic boron nitride (cB
N) is divided into burnt stones.

In these methods, studies have been made to find optimum conditions in consideration of finishing accuracy, economy, etc., which are always suitable for an object.

[0004]

However, in the method using the loose abrasives, since the abrasives easily flow during surface polishing or polishing, there is a problem from an economic point of view that a large amount of the abrasives is used. There have been various problems such as problems in the workplace environment such as scattering of abrasive grains generated during polishing, and problems in wastewater treatment such as clarification of highly turbid wastewater.

On the other hand, in the conventional fixed grindstone, since the abrasive grains are formed in a fixed state via a binder, clogging and burning due to the binder often occur. Further, in the production of a fixed grindstone using a binder such as an inorganic substance or an organic substance, it is extremely difficult to uniformly disperse the abrasive grains when using ultrafine abrasive grains (0.02 to 15 μm). That is, when a hard grindstone is manufactured, a large amount of a binder is required, and the abrasive grains are relatively reduced, and the dispersibility of the abrasive grains is reduced. In addition, when the abrasive particles are fine powder, the particle size of the binder is larger than the particle size of the abrasive particles, and a structure in which the binder is interposed between the particles of the abrasive particles cannot be obtained, and the function of the abrasive particles is substantially performed. Can not be done. In addition, it is difficult to uniformly mix powders of different types of abrasive grains, and the dry shrinkage is large. In addition, there is a problem that a large amount of the binder is used when mixing the abrasive powder and the binder.

[0006] In addition, the grinding wheels manufactured by these conventional methods have a reduced grinding ability due to scratches and shavings that cause polishing scratches on the surface of the polished workpiece that has been ground or polished, and which are welded to the grinding wheel use surface. There is a problem that clogging occurs and polishing burns in which the eyes of the grindstone are crushed occur.

The present invention has been made by paying attention to such problems existing in the prior art. The aim is to increase the dispersibility and uniformity of the abrasive grains,
An object of the present invention is to provide a grindstone capable of improving density, securing strength, and suppressing burn, clogging, and scratching in grinding, polishing, polishing, and the like, and a method for manufacturing the same.

Another object of the present invention is to improve the working environment by improving the precision, achieving a higher degree of mirror finish, and reducing the scattering of abrasive grains in the grinding and polishing steps, and at the same time reducing the manufacturing cost. An object of the present invention is to provide a grindstone that can be reduced and a manufacturing method thereof.

[0009]

Means for Solving the Problems In order to achieve the above object, the grinding wheel according to the first aspect of the present invention comprises only a sintered body of inorganic abrasive grains.

According to a second aspect of the present invention, in the grinding wheel according to the first aspect, the shrinkage is set to 1.0% or less. The manufacturing method of the grinding wheel according to the invention according to claim 3 is to form an inorganic abrasive containing a dispersant that disappears by firing into a predetermined shape by a casting method or a pressure forming method, and after drying the formed product, It is to be fired.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. The grindstone is substantially composed of only a sintered body of inorganic abrasive grains. In the method of manufacturing this grindstone, first, water and a dispersant or an alcohol, an organic solvent such as xylene, and a dispersant are used for an inorganic abrasive raw material selected in consideration of compatibility with an object to be ground, polished or polished. When added, a slurry in which the abrasive grains are in a dispersed state is produced. Polishing refers to polishing with high polishing accuracy such as mirror polishing.

The slurry is mixed and stirred using a ball mill, and the inorganic abrasive particles in the slurry are uniformly dispersed. Then, the slurry is formed into a predetermined shape by a casting method or a pressure forming method after deaeration and stirring in a vacuum state. Next, the molded product is dried and then fixed in shape by baking to produce a desired grindstone.

[0013] The raw material of the inorganic abrasive used in the grinding stone is
Considering compatibility with the object to be ground, polished or polished
Selected. Specifically, starting with diamonds,
Boron carbide (B_FourC), cubic boron nitride (cBN),
Boron nitride (BN), titanium carbide (TiC), boride
Tan (TiB), aluminum oxide (Al_TwoO_Three),acid
Titanium chloride (TiO_Two), Zirconium carbide (ZrC),
Niobium carbide (NbC), Tantalum carbide (TaC), Carbonized
Chrome (Cr_ThreeC_Two), Silicon nitride (Si_ThreeN _Four),acid
Zirconium (ZrO)_Two), Aluminum nitride (Al
N), tantalum nitride (TaN), silicon oxide (Si)
O_Two), Yttrium oxide (Y_TwoO_Three), Silicon carbide
(SiC), ferric oxide (Fe)_TwoO_Three), Cerium oxide
(CeO_Two), Barium oxide (BaO), chromium oxide
(CrO_Two) And bone ash (3CaO · P)_TwoO _Five)
Can be

As the inorganic abrasive raw material, one or more of these compounds are appropriately selected and used. In this case, cerium oxide, containing a rare earth element such as yttrium oxide, the resulting grindstone is relatively soft,
This is desirable because there is little risk of damaging the object to be polished.
The particle size of the inorganic abrasive raw material is desirably in the range from 0.02 to 15 μm from ultrafine powder to fine powder in order to perform polishing or the like.

As the dispersant, those having an ammonium polycarboxylate as a main component are preferably used in order to disperse abrasive grains to form a stable slurry. The amount of the dispersant added is changed according to the object to be ground or polished. The dispersant disappears at around 550 ° C. during firing.

The amount of the water to be added is adjusted within the range of 10 to 30% by weight in the slurry in accordance with the object to be ground, polished or polished. The ball mill is used for mixing and stirring the slurry. At this time, the conditions of the ball mill are selected in consideration of the uniform dispersion, the fluidity, and the density at the time of molding of the inorganic abrasive particles, and the material, diameter, weight and the like of the ball are selected.

The above-mentioned casting method is a method in which a slurry containing 10 to 30% by weight of a solvent is used and is formed using a gypsum mold. The pressure molding method is such that the solvent is 10 to 30% by weight.
The finished slurry is further diluted with a solvent to a concentration of 30 to 55% by weight to improve the compressibility or press workability and the green strength and sintered body strength. A foaming agent, a lubricant, a shape retention agent and the like are added. After mixing and stirring, the mixture is heated and dried at 150 to 230 ° C. for several seconds with a spray drier to perform granulation. afterwards,
The granules are placed in a mold and pressurized at a pressure in the range of 50 to 1000 kg / cm ² to obtain a molded product having a desired shape. In this pressure molding method, since the production of a large product is not easy, the molding operation is usually performed by a cast molding method.

The drying method is carried out by using a box-type, tunnel-type, or ventilation-band-type dryer using a heat source such as exhaust gas from a tunnel kiln, infrared rays, high frequency waves, or the like in order to remove moisture from the molded product.

[0019] The above-mentioned firing method comprises the steps of:
The temperature is raised to 00 to 1800 ° C. in 5 to 48 hours, and further maintained at the same temperature for 1 to 10 hours, followed by firing. The grindstone in the embodiment is suitably used for polishing a silicon wafer, ferrite, sapphire, or the like.
In that case, cerium oxide (Ce)
O ₂ ), silicon oxide (SiO ₂ ), barium carbonate (Ba)
One or more of CO ₃ ), titanium oxide (TiO ₂ ), and aluminum oxide (Al ₂ O ₃ ) are appropriately selected and used. The firing temperature is set in the range of 600 to 1200 ° C.

Since the grinding wheel manufactured as described above does not contain a conventional binder, its shrinkage ratio, that is, the ratio of the weight of the grinding wheel after firing to the weight of the molded product before firing is determined by the grinding wheel. 1. When the particle diameter is 0.02 to 2 μm;
It is set to a small value of 5% or less. When the particle size of the abrasive grains is 2 to 15 μm, the value is set to a smaller value of 1.0% or less. Thus, since the shrinkage ratio of the grindstone is small, the shape of the grindstone formed into a predetermined shape can be maintained.

As described above, according to this embodiment, the following effects are exhibited. In the whetstone of the embodiment, the inorganic abrasive grains are uniformly dispersed using a dispersant that disappears by firing without using a binder remaining after firing. For this reason, the obtained grindstone is formed substantially only of a sintered body of inorganic abrasive grains, and has a high density,
The required strength can be secured. Therefore, by selecting inorganic abrasive grains corresponding to the object, it is possible to greatly reduce the occurrence of polishing burns, clogging, and scratches, which are scratches caused by the grinding stone, during grinding. In the whetstone of the embodiment, when the polishing work is performed because the inorganic abrasive grains are not bonded by the binder remaining after firing, and the inorganic abrasive grains are bonded and fixed to each other. In addition, the scattering of abrasive grains can be reduced, and the surrounding environment can be kept clean. In the grindstone of the embodiment, since the inorganic abrasive grains are bonded and fixed as described above, the wear of the grindstone is small, and as a result, the consumption of the grindstone can be reduced, and the production cost can be reduced. Reduction can be achieved. -In the grindstone of the embodiment, the obtained grindstone can be adjusted to a desired water absorbency and hardness by controlling the adjustment of the raw material, the firing temperature, and the like. In the whetstone of the embodiment, a new slurry having a composition and a type suitable for the intended use can be produced by using fine powder inorganic abrasive grains or by mixing different types of slurries. . In the grindstone of the embodiment, the shrinkage rate is set to 2.
It can be set to a small value of 5% or less, and the particle size is 2 to 15μ.
In the case of m, the shrinkage can be set to a smaller value of 1.0% or less. Therefore, the whetstone can be formed into a predetermined shape, and the shape can be maintained for a long period of time. In the whetstone of the embodiment, since a slurry having extremely good fluidity can be obtained by the dispersant that disappears by baking, large ones of the inorganic abrasive particles are sequentially turned into fine particles due to friction between the particles. Therefore, at the time of casting, it is possible to obtain a molded body in a state very close to the closest packing. In the grindstone of the embodiment, while the inorganic abrasive powder is uniformly dispersed and fine, the density of the grindstone is higher, and the hardness and strength are appropriately adjusted according to the polishing object by the firing temperature. be able to. In the whetstone of the embodiment, a dense sintered body can be easily obtained, and in the firing step, the hardness after general firing can be freely controlled by raising the temperature or holding time. -The grindstone of the embodiment can set the water absorption in the range of 5 to 40% and the apparent porosity in the range of 5 to 60%, preferably 20 to 60%. Can increase the water absorption depending on the type of raw material used, and is useful as a grindstone having water absorption.

[0022]

[Examples] Hereinafter, the above embodiment will be described more specifically with reference to examples. (Example 1) 1680 g of distilled water and 60 g of dispersant (Celna D-305, manufactured by Chukyo Yushi) were added to 8320 g of aluminum oxide (Al ₂ O ₃ ) powder having an average particle size of 0.6 μm, 5mm in diameter
Of zirconia (ZrO ₂ ) balls were added to a 10-liter polyethylene ball mill container. This was mixed and stirred for 48 hours, and further degassed and stirred under vacuum to prepare a slurry.

The viscosity of the slurry was measured with a B-type viscometer of Tokyo Keiki Co., Ltd. (temperature at the time of measurement was 15.6).
° C), apparent viscosity is 1100 cps and pH is 9.17
Met.

Further, the obtained slurry was converted into a gypsum mold (65
× 65 × 6.8 cm). After drying, the temperature was raised to 1000 ° C. in 14 hours and calcined by maintaining the temperature at the same temperature for 1 hour.

At this time, the shrinkage due to firing is only 0.3% or less, the bulk specific gravity of the fired body is 2.584, the apparent porosity is 33.3%, and the water absorption is 12.8%. A whetstone having characteristics was able to be produced. Example 2 Cerium oxide (Ce) having an average particle size of 0.9 μm
O ₂₎ relative to the powder 3225G, aluminum oxide having an average particle diameter of 0. 6μm (Al ₂ O ₃₎ powder 1075g, distilled water 700 g, ammonium polycarboxylate dispersant mainly comprising (Chukyo Yushi Serna D- 305) 40 g,
A mixture of 5100 g of zirconia (ZrO ₂ ) balls having a diameter of 5 mm was placed in a 5-liter polyethylene ball mill container. This was mixed and stirred for 48 hours to prepare a slurry, which was then degassed and stirred under vacuum.

As a result of measuring the viscosity of the slurry in the same manner as in Example 1, the apparent viscosity was 440 cps and the pH was 9.5.
It was 0 (measuring temperature 16 ° C.). This slurry was cast in the same manner as in Example 1. Then, after drying,
The temperature was raised to 900 ° C. in 14 hours, and then calcination was performed at the same temperature for 1 hour. As a result, the shrinkage of the grindstone was 0.22% or less, the bulk specific gravity was 3.601, and the apparent porosity was 3
The water absorption was 5.28% and the water absorption was 9.70%. Example 3 Cerium oxide (Ce) having an average particle size of 0.9 μm
O ₂₎ relative to the powder 3225G, aluminum oxide (Al ₂ O ₃ having an average particle size of 0.6 .mu.m) powder 1075g, distilled water 700 g, ammonium polycarboxylate dispersant mainly comprising (Chukyo Yushi Serna D- 305) 37 g,
A mixture of 5100 g of zirconia (ZrO ₂ ) balls having a diameter of 5 mm was placed in a 5 liter polyethylene ball mill container. This was mixed and stirred for 48 hours to prepare a slurry. It was further degassed and stirred in vacuum.

This slurry (apparent viscosity 1300 cp
s, pH is 9.37, measurement temperature is 14 ° C), 500 g of walnut (walnut) husk grains (average particle size of 120 µm) is added and mixed. did.

After the obtained molded body is dried, it is heated to 900 ° C. for 1 hour.
The temperature was raised in 4 hours, and the mixture was calcined by holding at the same temperature for 1 hour.
993%, apparent porosity 44.90%, water absorption 21.
A 90% whetstone was obtained.

Therefore, it was demonstrated that the water absorption can be freely controlled by mixing walnut shell grains as an organic substance. In addition, as a confirmatory experiment, the grindstone of each embodiment was attached to a conventional lapping machine, and 1.
Each product of sapphire, silicon wafer, and ferrite finished to the surface roughness of 0S was polished under ordinary conditions. As a result, the surface roughness (Ra) was as fine as about 3 nm, and it was confirmed that polishing with extremely high precision could be performed.

The above-described embodiment can be modified and embodied as follows. Use of ammonium salt of polyacrylic acid, ammonium salt of polymaleic acid or the like as the dispersant.

When these dispersants are used, the inorganic abrasive grains can be uniformly dispersed, and at the same time, can be eliminated after firing. Further, a technical idea grasped from the embodiment will be described below. The particle diameter of the inorganic abrasive is 2 to 15 μm.
Whetstone described in 1.

In the case of such a configuration, the grindstone can be preferably used as a grindstone for pre-processing or general polishing. The whetstone according to claim 1, wherein the particle diameter of the inorganic abrasive grains is 0.02 to 2 m.

With this configuration, it is possible to perform extremely high-precision polishing compared to a conventional polishing grindstone, and it is suitable as a grindstone for mirror polishing. The grinding stone according to claim 1 or 2, wherein the inorganic abrasive grains contain a rare earth element.

With this configuration, the performance of the obtained grindstone, such as the density and strength, can be appropriately adapted to the object to be polished. The method according to claim 3, wherein the dispersant has a polycarboxylic acid ammonium salt as a main component.

With this configuration, the abrasive grains can be uniformly dispersed, and the grinding wheel can be manufactured efficiently. The grinding stone according to claim 1 or 2, wherein the inorganic abrasive grains are composed of two or more kinds.

With this configuration, the performance of each inorganic abrasive grain can be complemented, and a grindstone having performance suitable for the purpose can be obtained.

[0037]

As described above, according to the present invention, the following effects can be obtained. According to the grinding wheel of the invention described in claim 1, by increasing the dispersibility and uniformity of the abrasive grains,
Density and strength can be improved, and burns, clogging, scratches, and the like can be suppressed in grinding, polishing, and the like. Further, in the grinding and polishing steps, it is possible to improve the working environment by improving the precision, making the mirror surface more sophisticated, and reducing the scattering of the abrasive grains, and it is possible to reduce the manufacturing cost.

According to the grinding wheel of the second aspect of the present invention, since the shrinkage is set to 2.5% or less, the grinding wheel can be easily formed into a predetermined shape and the shape can be maintained. be able to.

Further, according to the method of manufacturing a grinding wheel according to the third aspect of the present invention, the abrasive is molded by a casting method or a pressure molding method and fixed by firing. In addition to solving problems such as wastewater treatment, a grindstone having desired performance can be easily manufactured.

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Toshihiro 2388-1 Shimoishicho, Toki City, Gifu Prefecture

Claims (3)

[Claims] 1. A grindstone composed only of a sintered body of inorganic abrasive grains. 2. The inorganic abrasive has a particle size of 0.02 to 2 μm.
The grinding wheel according to claim 1, wherein the shrinkage rate in the case of (1) is set to 2.5% or less. 3. A method for producing a grindstone in which inorganic abrasive grains containing a dispersant which disappears by firing are formed into a predetermined shape by a casting method or a pressure forming method, and the formed product is dried and fired.