JP5414706B2 - Superabrasive wheel and grinding method using the same - Google Patents

Description

  The present invention relates to a porous vitrified bond superabrasive wheel in which superabrasive grains are bonded by vitrified bond and a grinding method using the same.

Vitrified bond wheels are known in which superabrasive grains (diamond abrasive grains, CBN abrasive grains), general abrasive grains (SiC abrasive grains, AL ₂ O ₃ abrasive grains) and the like are used as abrasive grains and these are bonded by vitrified bonds.

JP 54-39292 A JP 59-161269 A Japanese Patent Laid-Open No. 3-184771

  However, when grinding is performed with a conventional vitrified bond wheel, there is a problem that the grinding resistance value increases and the grinding resistance value is not stable as the grinding process is continued.

In order to solve the above-mentioned problems, the present invention is a vitrified bond superabrasive wheel having a superabrasive layer in which superabrasive grains are bonded by vitrified bond, and is dispersed in the superabrasive layer. It is a vitrified bonded superabrasive wheel with a porous hole, characterized in that it includes small-sized pores and spherical large-diameter pores arranged in a dispersed manner.
The present invention includes spherical large-diameter pores arranged uniformly dispersed in the superabrasive layer, so that the total area of the pores exposed to the superabrasive layer is substantially constant in the process of wearing the superabrasive layer. Therefore, there is a feature that the area where the superabrasive layer acts on the workpiece does not change. Therefore, even if the grinding process is continued, the sharpness is always good and the grinding resistance value is stable at a low value.
A vitrified bond having a known composition can be applied to the present invention. For example, a vitrified bond having the following composition disclosed in the claims of Japanese Patent Laid-Open No. 54-39292 can be applied.
SiO _2: 40 to 60 _{wt%, AL} 2 O 3: _{2~14 wt%, B} 2 O 3: _{9~25 wt%, P} 2 O 5: _1~8 wt%, RO (RO is, CaO, MgO And one or more oxides selected from BaO): 3 to 14% by mass, R ₂ O (R ₂ O is one or more oxides selected from Li ₂ O, Na ₂ O and K ₂ O) : 2 to 4% by mass, ZrO ₂ : 2 to 20% by mass
More specifically, a vitrified bond having the composition of No. 1 to No. 8 in Table 1 disclosed in Example 1 of JP-A No. 54-39292 can be applied. Needless to say, the vitrified bond applicable to the present invention is not limited to these compositions, and other known compositions are also applicable.

In the present invention, the spherical shape has a substantially circular or substantially elliptical cross section, and the average value (hereinafter referred to as “sphericity”) of the ratio a / b between the minor axis a and the major axis b is 0.5 or more. 1 or less. Therefore, it does not require a three-dimensional shape whose cross section is a mathematically strict circle or ellipse, such as a strict true sphere or an elliptic sphere. The sphericity of the large pores used in the present invention is preferably 0.6 to 1.0, and more preferably 0.8 to 1.0.
In order to measure the sphericity, the superabrasive layer of the vitrified bond superabrasive wheel is accurately trued with a diamond dresser. Then, for 100 pores exposed on the surface of the superabrasive layer after completion of truing, the minor axis a and the major axis b are measured, and the average value of the ratio a / b is defined as the sphericity.
The shape of the small-diameter pores may be spherical or irregular, and the shape is not particularly limited. The reason is that in the present invention, the shape of the small diameter pores hardly affects the grinding characteristics.

In the vitrified bond superabrasive wheel of the present invention, the average pore diameter of the small pores is preferably 0.1 to 15 μm, and the average pore diameter of the large pores is preferably 20 to 200 μm.
The pores in the vitrified bond superabrasive wheel of the present invention are factors that have a large influence on the grinding characteristics. The average pore diameter of small pores is 0.1 to 15 μm, and the average pore diameter of large pores is 20 to 200 μm. It is preferable.
If the average pore size of the small pores is less than 0.1 μm, the cooling efficiency is unfavorable, and if it exceeds 15 μm, the bond bridge strength is undesirably lowered.
Furthermore, if the average pore size of the large pores is less than 20 μm, the chips are likely to clog, and if it exceeds 200 μm, the surface roughness of the ground surface becomes rough.
In order to measure the pore diameter, the superabrasive layer of the vitrified bond superabrasive wheel is accurately trued with a diamond dresser. Then, circles circumscribing the pores are measured at 100 pores exposed on the surface of the superabrasive layer after completion of truing, and the average value of the diameters of the circles is defined as the average pore diameter.

In the vitrified bonded superabrasive wheel of the present invention, the ratio of the total capacity of the small diameter pores and the large diameter pores to the superabrasive layer is preferably 40 to 80% by volume.
If the ratio of the total capacity of the small pores and the large pores to the superabrasive layer is less than 40% by volume, it is not preferable because sufficient effects of the invention cannot be obtained. If it exceeds 80% by volume, vitrified bond superabrasive grains Since the strength of a wheel falls remarkably, it is not preferable.

In the vitrified bond superabrasive wheel of the present invention, the large-diameter pores are preferably formed of a spherical pore-forming agent.
The pore forming agent is preferably a spherical material that disappears during the firing process. As a material, a resin, carbon, an inorganic hollow body, or the like is preferable.
Further, the pore forming agent is preferably spherical. In the present invention, the spherical shape has a substantially circular or substantially elliptical cross section, and the average value (hereinafter referred to as “sphericity”) of the ratio a / b between the minor axis a and the major axis b is 0.5 or more. 1 or less. Therefore, it does not require a three-dimensional shape whose cross section is a mathematically strict circle or ellipse, such as a strict true sphere or an elliptic sphere. The sphericity of the pore forming agent used in the present invention is preferably 0.8 to 1.0, and more preferably 0.9 to 1.0.
When the sphericity is measured, the pore-forming agent dispersed in the resin and cured is polished to a flat surface, and the cross section is observed. The minor axis a and the major axis b are measured at 100 locations of the pore-forming agent exposed on the surface of the resin after completion of polishing, and the average value of the ratio a / b is defined as sphericity.

In the vitrified bond superabrasive wheel of the present invention, the softening temperature of the vitrified bond is preferably 600 to 900 ° C.
When the softening temperature of the vitrified bond is less than 600 ° C., the holding power of the superabrasive grains decreases, which is not preferable.

  The vitrified bond superabrasive wheel of the present invention is preferable when it is used for grinding various wafers such as silicon, sapphire, and compound semiconductor, because sufficient effects of the invention can be obtained.

  Furthermore, the present invention provides a method of grinding various wafers such as silicon, sapphire, and compound semiconductor using a vitrified bond superabrasive wheel.

  According to the vitrified bond superabrasive wheel of the present invention, the sharpness is good and the grinding resistance value is stable at a low value.

  The mode for carrying out the invention will be described in detail in Examples.

The details of the vitrified bond superabrasive wheel of Example 1 of the present invention are as follows.
Vitrified bonds are listed in Table 1. 1 was used. That is, the composition of the vitrified bond is as follows.
SiO _2: 51.4 _wt%, AL ₂ O 3: 11 _{wt%, B} 2 O 3: 17.8 wt%
P ₂ O ₅ : 5.2% by mass, RO (RO is one or more oxides selected from CaO, MgO, and BaO): 6.2% by mass, R ₂ O (R ₂ O is Li ₂ One or more oxides selected from O, Na ₂ O and K ₂ O): 3.1% by mass, ZrO ₂ : 5% by mass, other: 0.3% by mass
As the superabrasive grains, diamond abrasive grains having an average particle diameter of 2 μm were used, and as the pore forming agent, the material was resin, the shape was spherical, and the average grain diameter was 100 μm.
After adding 20 volume% vitrified bond, 40 volume% diamond abrasive, and 40 volume% pore-forming agent, and adding a known binder, the chip-shaped molded body is molded by a press, and in an air atmosphere A binder removal treatment was performed, followed by firing at a temperature of 850 ° C. in an air atmosphere.
The chip after firing was bonded to an aluminum alloy base metal using an adhesive, and then truing and dressing using a conventional grindstone to complete the vitrified bond diamond wheel of Example 1.
The wheel is a segment type cup wheel (JIS B4131 6A7S type) having an outer diameter of 200 mm, a superabrasive layer width of 4 mm, and a superabrasive layer thickness of 5 mm.
In the completed vitrified bond diamond wheel, the average pore diameter of the small pores was 5 μm, the average pore diameter of the large pores was 100 μm, and the ratio of the total capacity of the small pores and the large pores to the superabrasive layer was 60% by volume. .
The vitrified bond diamond wheel of Example 1 was attached to a vertical rotary table type surface grinder, and silicon wafer was ground to confirm the effect of the present invention.
When grinding was performed, the sharpness was good and stable, and the wear amount in the thickness direction of the superabrasive layer was also small. When the amount of wear in the thickness direction of the superabrasive layer was measured after completion of the grinding, it was 1 μm. Further, the current value of the spindle motor during grinding was 7.2 A.
Here, the average particle diameter refers to an average particle diameter measured with a laser diffraction particle size distribution analyzer SALD series manufactured by Shimadzu Corporation.

(Comparative Example 1)
On the other hand, the vitrified bond diamond wheel of Comparative Example 1 uses a resin as the pore-forming agent, an irregular shape with an average particle size of 120 μm, and the rest of Comparative Example 1 under the same specifications and conditions as in Example 1. Completed the vitrified bond diamond wheel.
When the same grinding process as in Example 1 was performed, the sharpness was unstable and the wear amount in the thickness direction of the superabrasive layer was also large. When the amount of wear in the thickness direction of the superabrasive layer was measured after completion of the grinding, it was 1.2 μm. Further, the current value of the spindle motor during grinding was 8.5A.
The results of Example 1 and Comparative Example 1 are shown in Table 2.

  The present invention can be used in a superabrasive wheel for grinding various wafers in the semiconductor field and a processing method using this superabrasive wheel.

Claims (5)

A vitrified bond superabrasive wheel having a superabrasive layer in which superabrasive grains are bonded by vitrified bond,
Wherein the small pores having an average pore diameter which are arranged distributed in the superabrasive layer is 0.1-15, average pore diameter saw contains a large pores of spherical 20 to 200 [mu] m, the large pores of the spherical The average value of the ratio of the minor axis a to the major axis b (a / b) is 0.5 or more and 1.0 or less, and is used for grinding various wafers such as silicon, sapphire and compound semiconductors. A vitrified bonded superabrasive wheel with air holes. Wherein the small pores, the percentage of the total capacity occupied superabrasive layer of the large pores is characterized in that 40 to 80 volume%, claim 1 Symbol placement of vitrified bond superabrasive wheel. The vitrified bond superabrasive wheel according to claim 1 or 2 , wherein the large-diameter pores are formed of a spherical pore-forming agent. The vitrified bond superabrasive wheel according to any one of claims 1 to 3 , wherein a softening temperature of the vitrified bond is 600 to 900 ° C. How silicon, various wafers such as sapphire and compound semiconductor grinding using a vitrified bond superabrasive wheel according to any one of claims 1 4.