Patent US5494722A successfully refreshed from Google Patents.
US5494722A
Expired / Lapsed
US
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Magnetic recording medium and method for its production
Assignee: Resonac Holdings Corp
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Filing: 1993-01-26
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Granted: 1996-02-27
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Expires: 2013-01-26
Abstract
Abstract A thin-film rigid disk magnetic medium is prepared having a non-magnetic substrate and a magnetic alloy layer formed on the substrate with a non-magnetic underlayer containing chromium as the main component interposed therebetween, where the magnetic alloy layer contains cobalt as the main component and not more than 8 atomic % of boron, not more than 40 atomic % of nickel, not more than 26 atomic % of chromium and not more than 10 atomic % of tantalum. Preferably, the magnetic alloy layer is formed by sputtering while a voltage relatively lower than the plasma potential is applied to the non-magnetic substrate.
Inventors
- 👤 Masahiro Oka
- 👤 Fumiaki Yokoyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:22
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/656; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12458; Y10T428/12493; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12847; Y10T428/12854; Y10T428/12861; Y10T428/12931; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
82 words
A metal thin film rigid disk magnetic medium, comprising: a non-magnetic disk shaped substrate; a Co-Cr-Ni-B-Ta magnetic alloy layer formed on said substrate; a non-magnetic underlayer containing chromium as the main component interposed therebetween; and wherein said magnetic alloy layer consists essentially of cobalt as the main component and not more than 8 atomic % of boron, not more than 40 atomic % of nickel, not more than 26 atomic % of chromium and not more than 10 atomic % of tantalum.
Claim 2
Dependent Claim
82 words
A metal thin film rigid disk magnetic medium, comprising: a non-magnetic disk shaped substrate; a Co-Cr-Ni-B-Ta magnetic alloy layer formed on said substrate; a non-magnetic underlayer containing chromium as the main component interposed therebetween; and wherein said magnetic alloy layer consists essentially of cobalt as the main component and not more than 8 atomic % of boron, not more than 40 atomic % of nickel, not more than 26 atomic % of chromium and not more than 10 atomic % of tantalum.
Claim 3
Dependent Claim
20 words
The magnetic medium of claim 1, wherein said non-magnetic substrate is an aluminum alloy plate provided with a nickel-phosphorus layer.
Claim 4
Dependent Claim
33 words
The magnetic medium of claim 1, wherein said non-magnetic substrate is selected from the group consisting of a metal substrate, a glass substrate, a ceramic substrate, a carbon substrate and a silicon substrate.
Claim 5
Dependent Claim
31 words
The magnetic medium of claim 1, wherein said non-magnetic underlayer containing chromium as the main component is formed by sputtering while a negative bias voltage is applied to said nonmagnetic substrate.
Claim 6
Dependent Claim
20 words
The magnetic medium of claim 1, wherein said magnetic alloy layer contains from 0.005 to 8 atomic % of boron.
Claim 7
Dependent Claim
20 words
The magnetic medium of claim 5, wherein said magnetic alloy layer contains from 1 to 4 atomic % of boron.
Claim 8
Dependent Claim
20 words
The magnetic medium of claim 1, wherein said magnetic alloy layer contains from 10 to 35 atomic % of nickel.
Claim 9
Dependent Claim
20 words
The magnetic medium of claim 1, wherein said magnetic alloy layer contains from 5 to 26 atomic % of chromium.
Claim 10
Dependent Claim
20 words
The magnetic medium of claim 8, wherein said magnetic alloy layer contains from 6 to 10 atomic % of chromium.
Claim 11
Dependent Claim
20 words
The magnetic medium of claim 1, wherein said magnetic alloy layer contains from 0.005 to 6 atomic % of tantalum.
Claim 12
Dependent Claim
19 words
The magnetic medium of claim 10, wherein said magnetic layer contains from 2 to 5 atomic % of tantalum.
Claim 13
Dependent Claim
23 words
The magnetic medium of claim 1, wherein said magnetic alloy layer contains Co-Cr-Ni-B-Ta regions with a lower chromium concentration than surrounding Co-Cr-Ni-B-Ta regions.
Claim 14
Dependent Claim
24 words
The magnetic medium of claim 1, wherein the thickness of said magnetic alloy layer is within a range of from 200 to 800 Å.
Claim 15
Dependent Claim
16 words
The magnetic medium of claim 1, further comprising an overcoat layer on said magnetic alloy layer.
Claim 16
Dependent Claim
19 words
The magnetic medium of claim 1, wherein said magnetic alloy layer consists of cobalt, boron, nickel, chromium and tantalum.
Claim 17
Dependent Claim
27 words
The magnetic medium of claim 12, wherein the diameters of Co-Cr-Ni-B-Ta regions with a lower chromium concentration are within a range of from 10 to 500 Å.
Claim 18
Dependent Claim
25 words
The magnetic medium of claim 12, wherein the number of Co-Cr-Ni-B-Ta regions with a lower chromium concentration is from 600 to 100,000 regions/μm 2 .
Claim 19
Dependent Claim
15 words
The magnetic medium of claim 14, further comprising a lubricant layer on said overcoat layer.
Claim 20
Dependent Claim
18 words
The magnetic medium of claim 15, wherein said magnetic medium exhibits a coercivity of at least 2,035 Oe.
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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) | 1999-02-26 | 1999-08-28 | 2000-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-02-26 | 2003-08-28 | 2004-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-02-26 | 2007-08-28 | 2008-02-27 | $7700.00 | Window Closed / Lapsed |