US4608293A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composite substrate for a thin-film magnetic head
Assignee: Proterial Ltd
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Filing: 1983-03-02
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Granted: 1986-08-26
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Expires: 2003-03-02
Abstract
Abstract A composite substrate for a thin-film magnetic head comprises a substrate material, and an insulating oxide film formed thereon, and defining a smooth and stress-free surface having a surface roughness not greater than 50 Å. A film of a magnetic material having improved magnetic properties may be formed on the surface of the oxide film.
Inventors
- 👤 Toshiaki Wada
- 👤 Yoshiaki Katsuyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:50
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/31; G11B5/3163; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/18; H01F10/20; H01F10/26; H01F10/265; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/11; Y10T428/1157; Y10T428/24; Y10T428/24355
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
190 words
A composite substrate for a thin-film magnetic head comprising a substrate made of a material selected from the group consisting of soft magnetic and non-magnetic materials and an insulating film on said substrate, said insulating film having a surface opposite to said substrate which has a surface roughness not greater than 50 Å and is stress-free, said composite substrate being made by (1) providing a substrate made of a material selected from the group consisting of soft magnetic and non-magnetic materials, (2) forming an insulating film on said substrate, said insulating film having a surface opposite to said substrate, (3) placing said substrate with insulating film therein in an aqueous suspension containing between 0.5 and 20% by weight of one or more polishing powders selected from the group consisting of MgO, SiO 2 and Al 2 O 3 , each polishing powder having a particle diameter of not greater than 0.1 micron, and (4) polishing the insulating film on said substrate using a rotating polisher to provide a surface roughness to said insulating film of not greater than 50 Å and a stress-free character and thus form said composite substrate.
Claim 2
Dependent Claim
190 words
A composite substrate for a thin-film magnetic head comprising a substrate made of a material selected from the group consisting of soft magnetic and non-magnetic materials and an insulating film on said substrate, said insulating film having a surface opposite to said substrate which has a surface roughness not greater than 50 Å and is stress-free, said composite substrate being made by (1) providing a substrate made of a material selected from the group consisting of soft magnetic and non-magnetic materials, (2) forming an insulating film on said substrate, said insulating film having a surface opposite to said substrate, (3) placing said substrate with insulating film therein in an aqueous suspension containing between 0.5 and 20% by weight of one or more polishing powders selected from the group consisting of MgO, SiO 2 and Al 2 O 3 , each polishing powder having a particle diameter of not greater than 0.1 micron, and (4) polishing the insulating film on said substrate using a rotating polisher to provide a surface roughness to said insulating film of not greater than 50 Å and a stress-free character and thus form said composite substrate.
Claim 3
Dependent Claim
25 words
A composite substrate as set forth in claim 1, further including a film of a magnetic material formed on said surface of said insulating film.
Claim 4
Dependent Claim
31 words
A composite substrate as set forth in claim 1, wherein said substrate is made of a soft magnetic material selected from the group consisting of Mn-Zn ferrite, Ni-Zn ferrite and Sendust.
Claim 5
Dependent Claim
52 words
A composite substrate as set forth in claim 1, wherein said substrate is made of a non-magnetic material of high wear resistance and precision workability selected from the group consisting of Al 2 O 3 -TiC, Al 2 O 3 -TiO 2 and Al 2 O 3 -Fe 2 O 3 ceramics.
Claim 6
Dependent Claim
37 words
A composite substrate as set forth in claim 1, wherein said insulating film comprises a non-conductive material of high mechanical strength and hardness selected from the group consisting of Al 2 O 3 and SiO 2 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-08-25 | 1990-02-24 | 1990-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-25 | 1994-02-24 | 1994-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-25 | 1998-02-24 | 1998-08-26 | $7700.00 | Window Closed / Lapsed |