Etching a substrate: processes – Forming or treating article containing magnetically...
Patent
1996-12-02
1999-02-16
Powell, William
Etching a substrate: processes
Forming or treating article containing magnetically...
216 88, 216 91, 216 97, B44C 122
Patent
active
058716548
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for producing a glass substrate for a magnetic disk to reduce occurrence of flaws in its front surface.
BACKGROUND ART
In conventional methods for producing a glass substrate for a magnetic disk, there has been carried out such a method for processing a glass substrate into a concentric circular form, i.e., a doughnut-like form; conducting a lapping process for polishing it with use of separating abrasive grains on a metallic surface plate; and conducting further a polishing process wherein the surface having been lapped is polished with use of a polishing pad made of synthetic resin and separating abrasive grains having a finer grain size.
Washing was generally conducted between the lapping process and the polishing process, and an etching process for removing foreign substances on the surface of the glass substrate for a disk was not conducted. As a result, abrasive grains having a larger grain size produced during the lapping process and metallic particles resulted from the metallic surface plate for lapping were left in the polishing process which was conducted subsequent to the lapping process, and these caused occurrence of flaws in the surface of the glass substrate for a disk and a damage to the polishing pad.
As an example for the etching process, there has been known a method disclosed in, for instance, Japanese unexamined Patent Publication No. 230621/1995. The main purpose of this method is to reduce the depth of flaws existing in an inner circumferential area of the glass substrate to thereby increase the mechanical strength of the glass substrate. Accordingly, there is a condition that the depth of the glass substrate surface by the etching be deeper than 3 .mu.m. As another example, there is a case that an etching process is conducted as a texture (minute projections and recesses in a magnetic disk surface) forming technique to improve friction sliding characteristics to the magnetic head.
In this method, however, a polishing process is not used after the etching process. Accordingly, abnormal projections which exceed the height of the texture around the projections are formed at a masked portion in the glass substrate surface for a disk, due to deposition of dust or the like. When a magnetic disk produced by using such glass substrate is rotated at a high speed such as 3000 rpm and a magnetic head is floated above the disk at a height of 350 .ANG. for instance, there was a possible problem of causing head-crushing of the magnetic head or breakage of a portion in the magnetic disk surface. In this case, it is necessary to suppress the depth by the etching to be less than 350 .ANG. for instance. However, such a small amount (depth) of etching was insufficient to remove the abrasive grains and the like, and a liquid phase etching which was usually carried out made it difficult to control the depth by the etching.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to prevent abrasive grains deposited on the surface of a glass substrate for a magnetic disk in a lapping process and metallic particles produced from a metallic surface plate for the lapping process from being brought to a polishing process subsequent to the lapping process whereby occurrence of flaws in the polishing process is reduced.
The present invention is to solve the above-mentioned problem and to provide a method for producing a glass substrate for a magnetic disk which comprises: a magnetic disk; in a depth of 0.1 .mu.m to 3 .mu.m, and where the etching process has been conducted.
The present invention has been attained by finding that abrasive grains deposited on the main surface and a portion of inner or outer circumferential portion of the glass plate for a disk and fine particles produced from a metallic surface plate in the lapping process can be completely removed by conducting an etching process with use of an etching solution between the lapping process and the polishing process. In this case, when the depth by the etching is more tha
REFERENCES:
patent: 5131977 (1992-07-01), Morizane et al.
patent: 5268071 (1993-12-01), Sono et al.
patent: 5429711 (1995-07-01), Watanabe et al.
Hayashi Ichiro
Mannami Kazuo
Tokuma Atsushi
AG Technology Co., Ltd.
Powell William
LandOfFree
Method for producing a glass substrate for a magnetic disk does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing a glass substrate for a magnetic disk, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing a glass substrate for a magnetic disk will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2059195