Patent EP0263512B1 successfully refreshed from Google Patents.
EP0263512B1
Expired / Lapsed
EP
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Glass substrate for a magnetic disc and process for its production
Assignee: AGC Inc
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Filing: 1987-10-07
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Granted: 1994-06-01
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Expires: 2007-10-07
Abstract
No abstract record available.
Inventors
- 👤 Takashi Kijima
- 👤 Jyun Matsui
- 👤 Takaaki Sera
- 👤 Takayuki Kobayashi
- 👤 Shunji Takakusa
- 👤 Hiroshi Ogata
- 👤 Tu Dr. Chen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 11:34
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73921; G11B5/7368; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
56 words
A glass substrate for a magnetic disc having a finely and isotropically roughened surface, wherein the maximum height R max of the surface roughness is substantially not higher than 70 nm (700 Å) at a standard length of 250 µm and substantially not less than 5 nm (50 Å) at a standard length of 50 µm.
Claim 2
Dependent Claim
18 words
The glass substrate according to Claim 1, wherein the tops of mountains constituting the surface roughness are rounded.
Claim 3
Dependent Claim
22 words
The glass substrate according to Claim 1, which is made of a silicate glass containing at least 40% by weight of SiO₂.
Claim 4
Dependent Claim
67 words
A glass substrate for a magnetic disc having a finely and isotropically roughened surface on which a magnetic layer is to be formed by a process such as sputtering, plating or vapor deposition, wherein mountains constituting the surface roughness having heights within a range of from 5 to 70 nm (50 to 700 Å) are formed with pitches within a range of from 0.1 to 50 µm.
Claim 5
Dependent Claim
68 words
A process for producing a glass substrate for a magnetic disc, which comprises applying chemical etching treatment to a glass surface to form a surface roughness wherein the maximum height R max of the surface roughness is substantially not higher than 70 nm (700 Å) at a standard length of 250 µm and substantially not less than 5 nm (50 Å) at a standard length of 50 µm.
Claim 6
Dependent Claim
26 words
The process according to Claim 5, wherein the chemical etching treatment is conducted by contacting an aqueous solution containing a fluorine compound to the glass surface.
Claim 7
Dependent Claim
24 words
The process according to Claim 5, wherein the chemical etching treatment is conducted by contacting a gas containing hydrogen fluoride to the glass surface.
Claim 8
Dependent Claim
43 words
The process according to Claim 5, wherein the chemical etching treatment is conducted by contacting a gas containing from 0.01 to 10 mol% of hydrogen fluoride in an inert gas to the glass surface maintained at a temperature of from 5 to 90°C.
Claim 9
Dependent Claim
31 words
The process according to Claim 8, wherein the gas containing from 0.01 to 10 mol% of hydrogen fluoride in an inert gas has a relative humidity of not higher than 70%.
Claim 10
Dependent Claim
83 words
A process for producing a glass substrate for a magnetic disc, which comprises applying chemical etching treatment to a glass surface to form a roughened surface and then applying mechanical polishing treatment to the roughened surface to provide a surface roughness wherein the maximum height R max of the surface roughness is substantially not higher than 70 nm (700 Å) at a standard length of 250 µm and substantially not less than 5 nm (50 Å) at a standard length of 50 µm.
Claim 11
Dependent Claim
26 words
The process according to Claim 10, wherein the chemical etching treatment is conducted by contacting an aqueous solution containing a fluorine compound to the glass surface.
Claim 12
Dependent Claim
24 words
The process according to Claim 10, wherein the chemical etching treatment is conducted by contacting a gas containing hydrogen fluoride to the glass surface.
Claim 13
Dependent Claim
22 words
The process according to Claim 10, wherein the polishing is conducted to have the tops of mountains constituting the surface roughness rounded.
References Cited (Backward Citations)
No citation records indexed.
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