JPH11245161A - Abrasive material aqueous solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the polishing efficiency by adding the alkali material to the abrasive material aqueous solution so as to increase the alkaline. SOLUTION: An alkali electrolyte or sodium carbonate are mixed in the abrasive material aqueous solution (formed by mixing the pure abrasive material and adding the preservative) so as to increase the alkaline (pH value) of the abrasive material aqueous solution. The alkali electrolyte having the pH value 12 is used, and the pH value is maintained at 12 by mixing the abrasive grains. Since the sodium carbonate is alkaline, it shows the pH value 12 equal to the alkali electrolyte by mixing the pure abrasive grains. Polishing efficiency is improved by increasing the pH value of the abrasive material aqueous solution to the alkaline (pH value 10-pH value 12).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method for a workpiece in which an aqueous solution of an abrasive supplied to a rotary surface polishing apparatus is improved in rust prevention effect, plane parallelism, and polishing efficiency.

[0002]

2. Description of the Related Art Conventionally, for example, for adjusting the thickness of a piezoelectric vibrator, an aqueous abrasive solution and a rotary polishing apparatus (polishing apparatus) have been used.
Is mainly used. Surface polishing refers to cutting the piezoelectric material (crystal, etc.), which is the material of the piezoelectric vibrator, with the most precision of thickness, and then finishing the final thickness (in the case of a piezoelectric vibrator, converting the thickness to frequency (Calculate the precision). Abrasive materials used for polishing are generally alumina oxide (Al
Fine particles of ₂ O ₃ ) are used, and the polishing accuracy and the finished surface roughness vary depending on the size of the fine particles.

In addition, a so-called surface lapping machine (lapping machine) comprising an upper stool, a lower stool, a center gear and an internal gear is used for the basic structure inherited from ancient times. The working principle is that an aqueous abrasive solution is supplied from a powder ring attached to the upper platen, and between the upper gear and the lower platen, between the center gear and the internal gear via a piezoelectric vibrator holding plate called a carrier. The surface of the piezoelectric vibrator held by the carrier is polished by rotating the carrier with the abrasive aqueous solution, rotating the upper platen and rotating the carrier by its own weight, the lower platen, the center gear, and the internal gear. The thickness polishing of the vibrator is performed.

[0004] As described above, an aqueous abrasive solution is indispensable for performing the thickness polishing process. However, as described above, a mixture of silicon-based fine particles with pure water is used. Dispersion must be taken into account, and measures are generally eliminated by mixing chemicals such as sodium nitrite and amine, and at the same time, polishing by mixing chemicals such as sodium nitrite and amine. It is known that it also has the ability to improve efficiency.

[0005]

In recent years, electronic devices have been rapidly developed to become smaller, lighter, and more sophisticated. Among them, mobile communication devices (mobile phones) and portable small acoustic green regenerators are naturally carried and used on a daily basis. Under these circumstances, the components that make up these devices are also required to be small and highly accurate, and most of the recent electronic devices are controlled by a computer (CPU), and a piezoelectric (crystal) that strikes the heart of the electronic devices is controlled by a computer (CPU). The oscillator is in an important position as an important clock source.

[0006] Therefore, the processing accuracy of the piezoelectric vibrator is required to be higher than ever before in the manufacturing process of the piezoelectric vibrator. In the case of the aqueous abrasive solution described in the prior art, the polishing to be supplied to the polishing device when the surface polishing device is used. The proportion of the abrasive used for the direct polishing action in the aqueous material solution (abrasive) is generally 2 to 2.
It is said to be 3%, and there is a problem that processing accuracy and processing efficiency required for polishing are poor.

[0007]

SUMMARY OF THE INVENTION The present invention aims at improving the processing accuracy and processing efficiency over the aqueous abrasive solution described in the prior art, and uses an alkaline substance (alkali electrolyzed water, sodium carbonate) in the aqueous abrasive solution. ) Is added to further increase the alkalinity of the conventional aqueous solution of the abrasive.

The inventor of the present invention has proposed the use of an aqueous alkaline solution (a mixture of pure water and an abrasive to add a rust preventive agent) to a conventionally used abrasive aqueous solution by using alkaline electrolyzed water instead of pure water. An experiment was conducted in which an abrasive solution was prepared by mixing the mixture and a conventional abrasive solution to which sodium carbonate was further added, and ordinary surface polishing was performed.

In various experiments, when the aqueous solution of the abrasive is weakly alkaline, a negative potential is generated on the surface of the quartz crystal, a positive potential is generated in the abrasive particles, and the potential is substantially the same. Therefore, it was found that they were attracted to each other in the aqueous abrasive solution. on the other hand,
A conventional abrasive solution (having rust-preventing effect) forms an amine-based film around the quartz and abrasive grains and is adsorbed. Therefore, although there is a rust-preventing effect, the potential relationship between the quartz and the abrasive grains becomes unbalanced. In addition, the repulsive force between the abrasive particles is small, the dispersibility is poor, and the particles are fixed from agglomeration, resulting in poor redispersibility.

However, when alkaline electrolyzed water or sodium carbonate is added, the pH value rises and the surface charges of the quartz and the abrasive grains change, so that the abrasive grains repel each other and the dispersion and the rust prevention effect are improved. In particular, Na + of sodium carbonate activates the repulsive force between the abrasive grains to improve the dispersibility. Also, unlike the conventional abrasive aqueous solution, coagulation does not occur, so that re-dispersibility is possible without sticking.

According to the above-described potential relationship between the vibrator and the abrasive grains, the ratio at which the abrasive of the aqueous abrasive solution directly acts on the surface of the piezoelectric vibrator appropriately acts to improve the polishing efficiency. Since the processing time can be shortened and the polishing process itself can be performed uniformly, the polishing accuracy can be improved and the polishing variation can be reduced.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The present invention relates to a conventionally used abrasive aqueous solution (a slurry obtained by mixing an abrasive in pure water and adding a rust preventive agent).
By further mixing alkaline electrolyzed water or sodium carbonate instead of pure water, the alkalinity of the aqueous abrasive solution (pH value) is strengthened.

The applicant of the present invention conducted an experiment under the following conditions. For the experiment, an aqueous abrasive solution conventionally used (the abrasive was dissolved in pure water), an aqueous abrasive solution using alkaline electrolyzed water instead of pure water in which the abrasive was dissolved, and a conventional aqueous sodium abrasive solution (20%) were used. %) Is used to investigate and confirm the finished state (polishing time, polishing accuracy, polishing variation, etc.) of the surface polishing process when using three types of aqueous abrasive solutions of the aqueous abrasive solution to which% is added.

[0014] The abrasive is an abrasive aqueous solution obtained by dissolving generally used silicon-based fine particles (about # 4000) in pure water, alkaline electrolyzed water, and a mixed water of pure water and sodium carbonate. Polishing time, polishing accuracy, polishing dispersion, etc. can be improved by using the aqueous material solution itself. However, it is necessary to mix chemicals such as sodium nitrite and amine to add rust prevention measures and abrasive grain dispersion effect. Thus, the above-described effect can be further enhanced.
The surface polishing apparatus uses a commonly used 4-way polishing apparatus (a surface polishing apparatus having an upper surface plate, a lower surface plate, a center gear, and an internal gear and having a rotating mechanism).

FIGS. 1 and 2 show graphs summarizing the experimental results. FIG. 1 is a graph showing a change in polishing amount (transition of polishing process), and FIG. 2 is a graph showing a change in polishing thickness variation. As can be seen from the graph, the polishing amount and the polishing thickness variation were successfully improved as compared with the conventional abrasive aqueous solution. FIGS. 3 and 4 are graphs showing changes in polishing efficiency (FIG. 3) and polishing variations (FIG. 4) when a rust inhibitor is added to an aqueous abrasive solution under the same conditions.

[0016] The pH value of the conventional aqueous solution of the abrasive is pure water.
Value 7, the pH value of the aqueous solution of the polishing material becomes about 9 by mixing these because the polishing material (abrasive) itself is alkaline,
By further adding a rust inhibitor (pH value 11), the pH value of the entire aqueous abrasive solution becomes about 10. Also,
The alkaline electrolyzed water has a pH value of 12. When the abrasive grains are added and mixed, the pH value becomes 12 as it is. Since sodium carbonate has alkalinity, when abrasive grains are mixed with pure water, it shows a pH value 12 equivalent to that of alkaline electrolyzed water.

As described above, the polishing efficiency is improved by increasing the pH value to alkaline (pH value 10 to pH value 12) with respect to the conventional aqueous abrasive solution. Also, with respect to the polishing thickness variation, by improving the conventional thickness variation phenomenon, the variation amount can be reduced even if the polishing time becomes long. In particular, since sodium carbonate has a higher dispersion of abrasive grains than alkaline electrolyzed water, it is possible to stably supply an aqueous abrasive solution even when the polishing (processing) time is long. In the present embodiment, the polishing efficiency and the degree of dispersion are simply described for the aqueous solution mixed with the abrasive grains, but by adding a rust inhibitor to the abrasive aqueous solution as in the prior art, Needless to say, the polishing efficiency and the degree of variation can be further improved. Although the present invention has been described with reference to the example of polishing a piezoelectric vibrator, the present invention is also effective in surface polishing of semiconductor silicon, single crystal, metal processing, glass, and the like.

[0018]

According to the present invention, the ratio of the abrasive in the aqueous abrasive solution directly acting on the surface of the workpiece to be polished acts appropriately, thereby improving the polishing efficiency, shortening the processing time, and reducing the polishing time. It is possible to realize a reduction in the number of manufacturing steps and an improvement in the yield by performing the uniformity of the process.

[Brief description of the drawings]

FIG. 1 is a graph comparing the polishing efficiencies of a conventional aqueous abrasive solution, an aqueous alkaline electrolyzed abrasive solution, and an aqueous abrasive solution to which sodium carbonate is added.

FIG. 2 is a graph comparing polishing variances of a conventional aqueous abrasive solution, an aqueous alkaline electrolyzed abrasive solution, and an aqueous abrasive solution to which sodium carbonate is added.

FIG. 3 is a graph showing a change in polishing efficiency when a rust inhibitor is not added and when a rust inhibitor is added in addition to the comparison of FIG.

FIG. 4 is a graph showing a change in polishing variation when a rust inhibitor is not added and when a rust inhibitor is added in addition to the comparison of FIG. 2;

Claims (3)

[Claims] 1. A surface polishing process using an aqueous solution of an abrasive in which alumina oxide-based abrasive grains are dissolved in pure water, wherein the pH value in the aqueous solution of the abrasive is made weakly alkaline at 10 to 12. Abrasive solution. 2. The method according to claim 1, wherein
An aqueous abrasive solution characterized by using alkaline electrolyzed water to make the H value weakly alkaline. 3. The polishing agent aqueous solution according to claim 1, wherein
An aqueous abrasive solution characterized by adding sodium carbonate to make the H value weakly alkaline.