Adhesive bonding and miscellaneous chemical manufacture – Delaminating processes adapted for specified product – Delaminating in preparation for post processing recycling step
Patent
1992-09-10
1993-12-07
Hearn, Brian E.
Adhesive bonding and miscellaneous chemical manufacture
Delaminating processes adapted for specified product
Delaminating in preparation for post processing recycling step
65 31, 156635, 156637, 156625, H01L 2100
Patent
active
052680711
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process of forming irregularities on the surface of a magnetic recording glass disk substrate. More specifically, the present invention relates to a process of processing the surface of the glass substrate for use as a magnetic disk whereby the deterioration of the mechanical, magnetic and other properties of the substrate can be prevented for a substantial period of time.
Compositions comprising a magnetic disk substrate, a magnetic film and a protecting film, formed by processes such as sputtering, metal plating, vapor deposition and the like, are called magnetic recording media (referred to as "media" hereinafter).
The main composition of a magnetic memory device comprises the media and a magnetic head for recording and reproduction (referred to as "head" hereinafter). Typically, the head and the media are in contact with each other when the magnetic memory device commences operation. By rotating the media, a space is generated between the head and the surface of the media by the formation of an air layer. Once operating in this state, recording and reproducing operations can be carried out. When the operation of the memory device is terminated, the rotation of the media stops. The head and the media return to the contact state.
It should be understood that contact frictional force is generated when the operation of the memory device is commenced and terminated causing abrasion to the head and media. Such abrasion causes the mechanical and magnetic properties of the media to deteriorate. This frictional force is usually referred to as contact start stop resistance and is abbreviated as CSS.
If water is adsorbed onto the surface of a media in an atmosphere with high humidity, the water is diffused into an interstice of the head and the media, causing an agglutination phenomenon. Under these conditions, the head and the media may be exposed to a high degree of resistance when operation of the memory device begins. Such resistance may eventually cause damage to the head and destruction of the media. This phenomenon is usually referred to as head crash.
Since glass has an excellent smooth surface, is hard and has a high resistance against deformation together with few surface defects it is particularly useful as a magnetic disk substrate appropriate for high information density storage. (See Japanese Patent Laid-open No. 122707/1974).
The contacting area of the media surface with the head increases when a glass substrate is used due to the superior mirror surface property of the glass. As a result of an increased contacting area there is also an increase in frictional resistance and adhesion forces generated between the head and the media as compared with a media employing a substrate having a rougher surface than glass.
In order to overcome such problems, a method to reduce frictional force and adhesion force generated between a head and a media, by mechanically forming minute irregularities on the surface of a substrate has been disclosed (for example, Japanese Patent Laid-open No. 123906/1978). Alternatively, chemical etching may be used to form irregularities on the surface of a glass substrate (for example, Japanese Patent Laid-open No. 136035/1985). A method combining the two aforementioned methods has also been disclosed (for example, Japanese Patent Laid-open No. 160010/1988).
To improve the frictional property of a glass substrate, the minute irregularities formed on the surface of the glass are preferably 0.1 to several .mu.m in pitch and have a depth up to several tens of nm.
The present invention is carried out to solve the aforementioned problems caused by CSS resistance and head crash when using magnetic disk glass substrates.
Conventional mechanical processes, such as the process of forming irregularities by polishing a substrate with tapes coated with fine powders such as Al.sub.2 O.sub.3, SiC, etc., may cause the development of cracks on the surface of a fragile material including a glass substrate. The cracks have caused indisputable problems by damaging
REFERENCES:
patent: 3773489 (1973-11-01), Forker et al.
patent: 4747093 (1988-05-01), Benne et al.
patent: 4859505 (1989-08-01), Nakayama et al.
patent: 4985306 (1991-01-01), Morizane et al.
Kawakita Shinya
Oikawa Masahiro
Okuda Eiji
Sono Kenzou
Goudreau George
Hearn Brian E.
Nippon Sheet Glass
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