US5049451A
Expired / Lapsed
US
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High-coercivity thin-film recording medium
Assignee: WD Media LLC
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Filing: 1990-12-12
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Granted: 1991-09-17
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Expires: 2010-12-12
Abstract
Abstract A high-coercivity thin-film magnetic recording medium, and method of producing the medium, is disclosed. The medium has a sputtered chromium underlayer, preferably about 300-1,000 Å thick, and a sputtered magnetic layer, preferably about 200-800 Å thick, composed of an alloy containing between 70-80% cobalt, 10-20% chromium, 3-20% platinum, and 2-10% tantalum, formed on the chromium underlayer. The medium is characterized by high coercivity, resolution, amplitude and loop squareness value, and low bit shift.
Inventors
- 👤 Brij B. Lal
- 👤 Atef H. Eltoukhy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:16
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/7368; G11B5/7373; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12535; Y10T428/12597; Y10T428/12736; Y10T428/12743; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12847; Y10T428/12854
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
46 words
A magnetic recording medium comprising a substrate; a sputtered chromium underlayer on the substrate; and a sputtered magnetic layer composed of an alloy containing between 70-80 atom percent cobalt, 10-20 atom percent chromium, 3-20 atom percent platinum, and 2-10 atom percent tantalum, on the chromium underlayer.
Claim 2
Dependent Claim
46 words
A magnetic recording medium comprising a substrate; a sputtered chromium underlayer on the substrate; and a sputtered magnetic layer composed of an alloy containing between 70-80 atom percent cobalt, 10-20 atom percent chromium, 3-20 atom percent platinum, and 2-10 atom percent tantalum, on the chromium underlayer.
Claim 3
Dependent Claim
17 words
The medium of claim 1, wherein the sputtered alloy contains at least about 5 atom percent platinum.
Claim 4
Dependent Claim
19 words
The medium of claim 1, wherein the magnetic layer is sputtered to a thickness of between about 200-1,000 Å.
Claim 5
Dependent Claim
19 words
The medium of claim 1, wherein the underlayer is sputtered to a thickness between about 300 and 3,000 Å.
Claim 6
Dependent Claim
18 words
The medium of claim 4, wherein the magnetic layer is sputtered to a thickness between about 200-1,000 Å.
Claim 7
Dependent Claim
16 words
The medium of claim 5, which is characterized by a coercivity of greater than 1,800 Oersteds.
Claim 8
Dependent Claim
18 words
The medium of claim 5, which is characterized by a bit shift of less than about 16 nsec.
Claim 9
Dependent Claim
18 words
The medium of claim 5, which is characterized by a magnetic squareness ratio of greater than about 0.85.
Claim 10
Dependent Claim
21 words
The medium of claim 5, which is characterized by a signal resolution, at 31 kiloflux changes/in, of greater than about 85%.
Claim 11
Dependent Claim
26 words
The medium of claim 5, which is characterized by a signal amplitude, measured at a recording frequency of 5.11 MHz, of greater than about 340 microvolts.
Claim 12
Dependent Claim
74 words
The medium of claim 5, which is characterized by: (a) a coercivity greater than about 1,800 Oersteds; (b) signal resolution, at 31 kiloflux changes/in, of greater than about 85%; (c) signal amplitude, measured at a recording frequency of 5.11 MHz, of greater than about 340 microvolts; (d) a bit shift of less than about 16 nsec; (e) a loop squareness ratio of greater than about 0.85; and (f) a Brt greater than 18,000 Gauss-microinch.
References Cited (Backward Citations)
US5004652A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-16 | 1995-03-18 | 1995-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-16 | 1999-03-18 | 1999-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-16 | 2003-03-18 | 2003-09-17 | $7700.00 | Window Closed / Lapsed |