JPH08168954A - Method for preventing polishing flaw - Google Patents

Abstract

PURPOSE: To provide a method for preventing polishing flaws caused by abrasives. CONSTITUTION: The quality of an abrasive is conventionally evaluated on the basis of its average grain size. In view of the grain size distribution of abrasives, abrasives which contain grains of not less than a certain size in a greater proportion are excluded from abrasives with an almost equal average grain size, so that polishing flaws can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing agent for polishing a material, and more particularly to a polishing agent selecting method for reducing the rate of occurrence of polishing scratches in the polishing agent for polishing a glass substrate for liquid crystal.

[0002]

2. Description of the Related Art Polishing glass to smooth the surface,
Alternatively, in the case of flattening the surface, free-abrasive grain type polishing using an abrasive such as cerium oxide is most often performed. For example, the surface of a glass substrate for liquid crystal used in displays of recent personal computers, word processors, etc. is usually polished by a single-sided swing type polishing machine called an Oscar type polishing machine. In this Oscar type polishing machine, while rotating a platen with a polishing cloth attached at a constant speed, a slurry liquid containing an abrasive such as cerium oxide is poured onto the polishing cloth, while the glass substrate attached to the glass holding member is fixed. It is pressed against the polishing cloth on the plate with a constant polishing pressure. At this time, since the glass holding member can freely rotate about its center, it swings on the plate while freely rotating according to the rotation of the plate. It has a structure.

The abrasive used here is an abrasive composed of fine powder having a particle size of mainly about 1 to 2 μ. The particle size depends on the smoothness of the polishing surface, the polishing rate, and the polishing scratches. It is known to be deeply involved in quality such as. However, as is well known, the particle size of powder is not constant and has various particle sizes. Therefore, usually, the median diameter or mode diameter of the measured particle size distribution of the powder has been used as the representative diameter of these various particle diameters. This also applies to the abrasives, and various types of abrasives are mainly classified by average particle size. In the past, it was customary to regard this average particle size as an index of the rate of occurrence of polishing scratches, and to obtain a lot having a relatively small average particle size in one product type.

[0004]

The average particle size of the abrasive is a typical characteristic value that determines the characteristics of the abrasive, and can be said to be an appropriate characteristic value when the abrasives are simply distinguished.
The abrasive particles involved in the polishing flaw are not essentially particles of average particle size, but rather large particles in the particle size distribution. Therefore, it is not appropriate to use the average particle size of the abrasive as an index of the occurrence rate of polishing scratches. For example, there are lots with a large scratch occurrence rate even in lots with a small average particle diameter, which is a problem that can be seen only after actually performing polishing. The present invention has been made in view of such conventional problems, and it is an object of the present invention to provide a method of predicting the occurrence rate of abrasive scratches and preventing the occurrence of polishing scratches in advance.

[0005]

In order to achieve the above object, in the method for preventing polishing scratches of the present invention, the proportion of particles having a certain size or more in the entire particle size distribution of the measured abrasive is measured. Is used as an index of the rate of occurrence of scratches to prevent the occurrence of scratches.

[0006]

The polishing scratches generated on the surface of the glass substrate are considered to be caused by large particles having a size of 5 to 10 μ or more in view of their size and shape. Therefore, in order to predict the occurrence rate of polishing scratches caused by the abrasive, it is necessary to know the proportion of large particles contained in the abrasive. This can be achieved by measuring the particle size distribution of the abrasive and using not the average particle size of the obtained particle size distribution but the ratio of large particles to the whole as an index.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 and Fig. 2 show the results of particle size distributions of two types of abrasive lots with different polishing scratch generation rates by a laser diffraction type granulometer
Shown in Lot A in FIG. 1 is an abrasive lot having a polishing flaw occurrence rate of 1.9% and has an average particle size of 2.5 μ, whereas lot B in FIG. 2 has a polishing flaw occurrence rate of 0.8. %, The average particle size was 2.4 μ and the polishing scratch occurrence rate was half or less, but there was almost no difference in the average particle size, and the particle sizes were almost the same.

On the other hand, in the judgment for preventing the occurrence of polishing scratches of the present invention, the proportion of large particles of 5 μ or more in the whole is 14.6% for lot A and 11.7% for lot B. It should be noted that there is a large difference between the lot A and the lot B at 5.4% and 3.5% in the proportion of large particles of 10 μ or more. .

Next, FIG. 3 shows the relationship between the rate of occurrence of polishing scratches in various abrasive lots and the proportion of large particles in the abrasive lots. It can be seen that the larger the proportion of large particles in the lot, the higher the rate of occurrence of polishing scratches. Therefore, the evaluation method of the present invention can accurately predict the rate of occurrence of polishing scratches and prevent the occurrence of polishing scratches.

[0010]

EFFECT OF THE INVENTION By measuring the particle size distribution of an abrasive and using the ratio of large particles in the particle size distribution to the whole as an index of the rate of occurrence of polishing scratches, the occurrence of polishing scratches caused by the abrasive is predicted. Therefore, the quality of the polishing agent can be judged. As a result,
It is possible to judge the quality of the polishing agent before using it, and it is possible to eliminate the waste that polishing scratches occur after the conventional use and polishing lots are exchanged. .

[Brief description of drawings]

FIG. 1 Particle size distribution of abrasive lot A with a large scratch rate

[Fig. 2] Particle size distribution of abrasive lot B with a small scratch rate

FIG. 3 is a graph showing the relationship between the proportion of large particles in the abrasive and the rate of occurrence of polishing scratches.

Claims (1)

[Claims] 1. An abrasive having an average particle size of approximately the same,
A method for preventing polishing scratches, which comprises selecting an abrasive having a small mixing ratio of large particles in the particle size distribution of the abrasive.