US5057200A
Expired / Lapsed
US
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Method of forming thin-film recording medium
Assignee: WD Media LLC
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Filing: 1991-03-14
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Granted: 1991-10-15
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Expires: 2011-03-14
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
2026-11-01 17:49
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/7368; G11B5/7373
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
45 words
A method of forming a magnetic recording medium comprising sputtering a chromium underlayer onto a substrate, and sputtering onto the underlayer, magnetic layer composed of an alloy containing in atomic percent between 70-80 percent cobalt, 10-20 percent chromium, 3-20 percent platinum, and 2-10 percent tantalum.
Claim 2
Independent Claim
45 words
A method of forming a magnetic recording medium comprising sputtering a chromium underlayer onto a substrate, and sputtering onto the underlayer, magnetic layer composed of an alloy containing in atomic percent between 70-80 percent cobalt, 10-20 percent chromium, 3-20 percent platinum, and 2-10 percent tantalum.
Claim 3
Dependent Claim
20 words
The method of claim 1, wherein the sputtering steps are carried out at a temperature greater than about 250° C.
Claim 4
Dependent Claim
21 words
The method of claim 1, wherein the alloy is sputtered onto the underlayer to a magnetic film thickness of about 200-800Å.
Claim 5
Dependent Claim
78 words
The method of claim 3, wherein the magnetic recording disc is characterized by: (a) a coercivity greater than about 1,800 Oerstads; (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.
Claim 6
Independent Claim
37 words
A method of forming a magnetic layer in a thin-film medium comprising applying to a magnetic medium substrate, an alloy containing in atomic percent 70-80 percent cobalt, 10-20 percent chromium, 3-20 percent platinum, and 2-10 percent tantalum.
Claim 7
Independent Claim
37 words
A method of forming a magnetic layer in a thin-film medium comprising applying to a magnetic medium substrate, an alloy containing in atomic percent 70-80 percent cobalt, 10-20 percent chromium, 3-20 percent platinum, and 2-10 percent tantalum.
Claim 8
Dependent Claim
13 words
The method of claim 4, wherein said applying is carried out by sputtering.
References Cited (Backward Citations)
US4236946A
Cited
US4576700A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-10-14 | 1995-04-15 | 1995-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-10-14 | 1999-04-15 | 1999-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-10-14 | 2003-04-15 | 2003-10-15 | $7700.00 | Window Closed / Lapsed |