JPS6368366A - Polishing method - Google Patents

Abstract

PURPOSE:To effectively cool the frictional heat generated on a polished article by carrying out polishing by intermittently jetting water and halogenated hydrocarbon separately onto the polishing surface of a liquid bond grindstone which is shaped by mixing liquid with abrasive grains. CONSTITUTION:When a turnable 2 on which a liquid bond grindstone 1 is loaded is revolved, and a polished member 5 installed onto a jig 4 at the lower edge of a spindle 3 is pressed and polished through planetary revolution, water is jetted in mist form onto the surface of the grindstone 1, and halogenated hydrocarbon solution is jetted in mist form once per polishing in 10min. As the halogenated hydrocarbon solution, used is the substance having the boiling point lower than that of water and higher than the normal temperature and having a large vaporization heat, for example, 1.1.2- trichloro-1.2.2-trifluroethane. Therefore, the frictional heat can be effectively removed, and a silicone wafer, etc. can be surface-polished favourably free from the strain or working deterioration of the polished member due to heat.

Description

[Detailed Description of the Invention] <Industrial Application Fields> The present invention involves intermittently spraying wood and a cooling liquid separately onto the polishing surface of a liquid pound grindstone formed by mixing abrasive grains with a liquid. The present invention relates to a polishing method for polishing a material to be polished.

<Conventional technology> A liquid is placed between the abrasive grains, and the material to be polished is pressed against a liquid pound grinding wheel that holds the abrasive grains using the surface tension and adhesive force of the liquid, and the relative relationship between the grinding wheel and the material to be polished is A polishing method in which a material to be polished is polished using a movement difference is disclosed in a patent application published by the present applicant in 1983, for example.
This has already been proposed in No. 0-269350 or Japanese Patent Application No. 155024/1982.

In addition, the present inventors have described a polishing method using a liquid pound grinding wheel in the Proceedings of the 1986 Society for Precision Engineering Spring Conference Academic Lectures, page 569, and the Proceedings of the Japan Society of Mechanical Engineers (0th edition), Vol. 51, No. 47.
No. 1 (published in November 1985), page 3145, Production Research Vol. 37, No. 7 (edited by Institute of Industrial Science, University of Tokyo, 198
Published in July 2015), etc.

The content of the above-mentioned applications and documents is that the material to be polished is pressed against the surface of a liquid pound grinding wheel that holds the abrasive grains by filling the gaps between the abrasive grains in a close-packed state with an appropriate liquid, and then This is a method of polishing a material to be polished using a grindstone using a relative movement difference between the two.

(Problems to be Solved by the Invention) In the seven methods described above, heat is generated due to friction between the material to be polished and the liquid pound grinding wheel.This heat increases as the pressing force of the material to be polished against the grinding wheel increases. This may cause distortion of the polished material due to heat or deterioration due to machining.

Therefore, when a normal hard grindstone is used to cool down the frictional heat, water or oil can be supplied to the grindstone surface. However, in a liquid pound whetstone in which the abrasive grains are held by liquid, the holding power of each abrasive grain is extremely weak, so if water or oil is poured onto the whetstone, it will disintegrate.

Also, even if water does not disintegrate when poured onto the whetstone, it will soften and the self-dressing effect will progress too much.
The wear and tear on the grindstone increases significantly.

Furthermore, spraying a small amount of cooling liquid such as water onto the grindstone cannot provide a sufficient cooling effect, and the liquid immediately evaporates due to frictional heat, so that the self-dressing effect does not work.

There is also a method that does not directly supply cooling liquid to the surface of the grinding wheel, but instead uses liquid to cool the supporting tools that contact the bottom and side surfaces of the grinding wheel, the jigs that support the material to be polished, etc. to the IMR level. Because it has a porous structure and has countless fine bubbles inside, it has poor thermal conductivity and cannot effectively cool the polished surface.

(Means for Solving the Problems) The present invention has been proposed in view of the above, and is made by applying water and a halogenated hydrocarbon solution separately to the polishing surface of a liquid pound grindstone, which is formed by mixing a liquid on a grinding shaft. This is characterized in that the material to be polished is polished while being sprayed intermittently.

(Example) The present invention will be described in detail below.1 The liquid pound grindstone according to the present invention has a liquid present between the abrasive grains, and the abrasive grains are held by the surface tension or adhesive force of the liquid.

The abrasive grains used in the above whetstones include diamond, corundum, emery, garnet, silica, tripoli, calcined dolomite, fused alumina, artificial emery, silicon carbide,
Any abrasive grains that can be used as normal abrasive grains, such as boron carbide, iron oxide, calcined alumina, chromium oxide, cerium oxide, and zirconium oxide, may be used.

The particle size of the abrasive grains may be approximately 30 gm or less.

On the other hand, the liquid used in the liquid pound grindstone of the present invention is used to hold the above-mentioned abrasive grains by surface tension or adhesive force, and is water or a water-soluble substance (alkaline solution,
Acid solutions, aqueous solutions of many other salts, polymer solutions, oily liquids, magnetic fluids, etc.) can be used.

The liquid pound whetstone of the present invention is manufactured by mixing the above-mentioned abrasive grains and liquid, and the abrasive grains in the whetstone are 30 to 70%.
It is about 1% of vo. Then, the abrasive grains and liquid are not only simply mixed, but also a diluent is added if necessary, and dry or semi-dry molding is performed, but it is preferable to compression mold the abrasive grains to form a V& dense state.

When polishing a material to be polished using a liquid pound grindstone formed as described above, a small amount of water and the amount of halogenated hydrocarbon required to cool the material to be polished are added to the grinding surface of the grindstone. The solution is intermittently sprayed onto the polishing surface of the grindstone while polishing.

The halogenated hydrocarbon solution used in the present invention includes:
As mentioned above, there is almost no solubility or reactivity with water,
It is desirable that the lighting point is below the boiling point of water, the heat of vaporization is large, and the flammability and toxicity are low.

Examples of halogenated hydrocarbon solutions that satisfy the above conditions include carbon tetrachloride, methyl chloride, l-1-l-trichloroethane, trichloroethylene, fluorodichloromethane, dichlorodichloromethane, chlorotrichlormethane, and trifluoromonofluoromethane. , difluorochloroethane, 1Φ1 self-2-trichlor-1,2,2-tri7
Among the above-mentioned components, the one most suitable for the present invention is one whose lighting temperature is lower than that of water, slightly higher than room temperature, and has a large heat of evaporation.・2-Trichloro-1-2-2-triple olethane (hereinafter R-1
13) can be used.

Therefore, in the following explanation, the case where R-113 is used as the halogenated hydrocarbon solution will be explained.

Water is an excellent cooling liquid, but if you spray a large amount of water onto a liquid pounding wheel that uses water as a pounding agent, the wheel may collapse. Keep it moist. However, if the liquid pound grindstone contains sufficient water, it is not necessary to spray water onto the polishing surface of the grindstone.

In this way, the reason why water is sprayed onto the grinding wheel is to prevent R-113 from penetrating into the grinding wheel when R-113 is next sprayed as a cooling liquid, and to achieve extremely good self-dressing. This is to make it work.

If a water-soluble substance is used instead of water as a ponding agent, it is necessary to spray a slightly larger amount of water than when water is used as a pulsing agent in order to liquefy the water-soluble substance. However, in this case as well, the pounding agent on the surface of the grinding wheel is limited to a level that liquefies, and it is not possible to spray in such a large amount that the entire grinding wheel becomes soft.

As described above, after water is sprayed onto the grindstone, R-113 is sprayed onto the surface of the grindstone.

This R-113 liquid hardly dissolves in water, so when R-113 is sprayed onto the surface of a whetstone that has water, it is blocked by the water contained inside the whetstone as a pounding agent and by the previously sprayed water, causing the whetstone to deteriorate. It cannot penetrate inside and remains on the surface of the grindstone, effectively cooling the material to be polished, and will not soften or disintegrate the grindstone even when sprayed in large quantities.

Moreover, even in the case of a whetstone using a water-soluble substance as a pounding agent, since this water-soluble substance does not dissolve in R-113, there is no possibility that the whetstone will soften.

In addition, since R-113 has an evaporation heat of 35.07 cal/rc', it evaporates extremely easily, so the heat generated by contact between the material to be polished and the grinding wheel is consumed as latent heat, effectively preventing the A temperature of the material to be polished. do.

The amount of R-113 sprayed can be increased or decreased as appropriate depending on the amount of heat generated during polishing and the temperature rise limit allowed by the material to be polished.

Specifically, while measuring the temperature of the material to be polished during polishing, R
It is only necessary to adjust the injection N amount of -113.

In addition, during polishing, R-113 comes into contact with water on the surface of the whetstone and inside the whetstone, mixing, stirring, etc., but R-113 evaporates extremely quickly and stagnates on the surface of the whetstone for a long time. Unless an extremely large amount is sprayed, R-11 will not form an emulsion with water, delaying evaporation, or penetrating into the inside of the grinding wheel, causing it to soften.
3 is not flammable, inhalable, or toxic, so even if it evaporates during work, it will not harm your health or cause any pollution problems.

Then, as the polishing process progresses, the surface layer of the whetstone that has been moistened by spraying water is scraped off by the material to be polished and self-dressing is performed, so water is periodically sprayed and R-113 is also sprayed. The material to be polished is polished by repeating this operation intermittently.

This polishing method cannot be applied to liquid pounding wheels that use oil or oil-soluble substances as a pounding agent, because R-113 is compatible with oil or oil-soluble substances and easily penetrates into the inside of the grinding wheel by spraying. It is.

There is also a component similar to R-113 that evaporates slowly, but if you use this component, the cooling effect tends to be insufficient when polishing at high speed, and it tends to form an emulsion with water. Unfavorable, also R-11
Although similar to 3.

Since components that evaporate quickly evaporate in a short time when sprayed, they cannot cover the surface of the grindstone and prevent water from evaporating, so a self-dressing function cannot be expected.

FIG. 1 shows an example of an apparatus for carrying out the method of the present invention.
It consists of a rotary table 2 on which a liquid pound grindstone l is placed, and a spindle 3 that can press the workpiece attached to the tip onto the surface of the rotary table 2 using hydraulic pressure. A mounting jig 4 is provided. and.

The workpiece 5 attached to the jig 4 faces a position other than the center of rotation on the upper surface of the grinding wheel 1, and the rotary table 2 and spindle 3 are rotated in the same direction and at the same number of rotations. The material 5 is caused to move planetarily relative to the grindstone l.

In a specific embodiment of the present invention, a silicon wafer with a diameter of 3 inches is attached to a jig 4 as the material to be polished 5 with wax, and the grindstone 1 is made of silicon carbide with an average particle diameter of 3 microns using water as a pounding agent. The grains were shaped into a disk with a diameter of 220 mm.

Then, after spraying 7 milliliters of water in a fine mist onto the polishing surface of the whetstone, the processing pressure was increased to 3 kg/cm.
2. Polishing was performed at a rotation speed of 10 orpm.

When the temperature was continuously measured on the side of jig 4, it was 20°C before the start of polishing, but 30°C 10 minutes after the start.
It rose to . Then, when polishing for 10 minutes and stopping for 5 minutes is repeated as a - cycle, the temperature on the side surface of the jig 4 further increases as shown in Fig. 2, and after 1 hour and 10 minutes of reading the 5th cycle, the temperature at the side surface of the jig 4 rises to 48. ℃, and at this point the wax to which the silicon wafer was attached melted and the silicon wafer was peeled off from the jig 4.

Although the temperature of the silicon wafer was not directly measured in the polishing process described above, the melting point of the wax used to attach the silicon wafer was 140. 'C, the surface temperature of the silicon wafer was above the melting point of the wax, and there was a significant temperature rise.

Note that the self-dressing effect of the grindstone during the polishing process was measured by the amount of cut into the silicon wafer, and the result was 1 millimeter, which is not necessarily sufficient.

Next, spray 7 milliliters of water in a fine mist on the surface of the grinding wheel 1, and immediately perform polishing under the same conditions as above. During each 10-minute polishing session, 7 milliliters of R-113 was applied each time. was made into a fine mist and was sprayed onto the surface of the grinding wheel. When the above cycle of polishing for 10 minutes and stopping for 5 minutes was repeated 5 times, the temperature change on the side surface of the jig during this period was as shown in FIG. 3, and there was almost no temperature change. Also, the depth of cut at this time is approximately 3 mm.

The self-dressing effect worked effectively.

On the other hand, in the same polishing process as above, R-113
The polishing was carried out by spraying only water without using polishing, but the total amount of water required to maintain the same temperature transition as above was approximately 80 milliliters after repeating the polishing four times. In this polishing process, the grinding wheel was significantly worn out, and the depth of cut reached approximately 6 millimeters up to the fourth time, and the grinding wheel collapsed in the middle of the fifth polishing.

(Effects of the Invention) In summary, according to the present invention, water and a halogenated hydrocarbon solution are separately and intermittently sprayed onto the polishing surface of a liquid pound grindstone formed by mixing abrasive grains with a liquid. Since it is characterized by polishing the material, even if frictional heat is generated between the material to be polished and the grindstone, it can be effectively cooled, and the material to be polished will not be distorted or deteriorated due to processing due to heat. do not have.

In addition, the liquid pound grinding wheel, which has extremely low physical strength, has a very low degree of collapse or wear and can withstand long-term polishing, and can be particularly effectively used for polishing the surfaces of silicon wafers and the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for carrying out the method of the invention;
FIG. 2 is a temperature rise diagram of the material to be polished when the method of the present invention is not carried out, and FIG. 3 is a diagram of the temperature rise of the material to be polished when the method of the present invention is carried out.

Claims (2)

[Claims] (1) On the polishing surface of a whetstone formed by mixing abrasive grains with liquid,
A polishing method characterized in that a material to be polished is polished while water and a halogenated hydrocarbon solution are separately sprayed intermittently. (2) The polishing method according to claim (1), wherein the halogenated hydrocarbon solution has almost no solubility or reactivity with water, and has a boiling point below the boiling point of water.