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US4472248A
Expired / Lapsed
US
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Method of making thin-film magnetic recording medium having perpendicular anisotropy
Assignee: 3M Co
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Filing: 1982-12-20
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Granted: 1984-09-18
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Expires: 2002-12-20
Abstract
Abstract A magnetic recording medium having a magnetizable metallic thin-film layer of perpendicular anisotropy can be produced at commercially viable production rates by electrodepositing cobalt, hypophosphite, and preferably also nickel ions at a plating bath temperature of 50°-80° C. and a plating current density of at least 20 mA/cm 2 .
Inventors
- 👤 David C. Koskenmaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:20
CPC Classifications
C; C25; C25D; C25D3/00; C25D3/02; C25D3/56; C25D3/562; G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/657; G11B5/84; G11B5/858
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
124 words
Method of making a magnetic recording medium comprising electrodepositing onto an electrically conductive substrate a magnetizable layer from an aqueous plating bath having a pH between 2 and 6 and including at least cobalt and hypophosphite ions in concentrations within the range of 0.2 to 1.0 N and 0.1 to 0.4 N, respectively, the weight ratio of Co to P in the magnetizable layer being between 5:1 and 50:1, wherein the improvement comprises maintaining a bath temperature and a plating current density within Region I of FIG. 2 of the drawing while maintaining a plating current density of at least 20 mA/cm 2 and a bath temperature between about 60° and 80° C., under which conditions the deposited layer has predominantly perpendicular magnetic anisotropy.
Claim 2
Dependent Claim
124 words
Method of making a magnetic recording medium comprising electrodepositing onto an electrically conductive substrate a magnetizable layer from an aqueous plating bath having a pH between 2 and 6 and including at least cobalt and hypophosphite ions in concentrations within the range of 0.2 to 1.0 N and 0.1 to 0.4 N, respectively, the weight ratio of Co to P in the magnetizable layer being between 5:1 and 50:1, wherein the improvement comprises maintaining a bath temperature and a plating current density within Region I of FIG. 2 of the drawing while maintaining a plating current density of at least 20 mA/cm 2 and a bath temperature between about 60° and 80° C., under which conditions the deposited layer has predominantly perpendicular magnetic anisotropy.
Claim 3
Dependent Claim
34 words
Method as defined in claim 1 wherein the bath includes nickel ions from about 0.4N to 1.5N in concentration, and the weight ratio of Ni to Co does not exceed about 3 to 2.
Claim 4
Dependent Claim
17 words
Method as defined in claim 1 wherein the current density is at least 100 mA/cm 2 .
Claim 5
Dependent Claim
20 words
Method as defined in claim 1 wherein the bath includes a buffering agent within the range of 1.0 to 3.0N.
Claim 6
Dependent Claim
13 words
Method as defined in claim 4 wherein the buffering agent is ammonium chloride.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-09-18 | 1988-03-19 | 1988-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-18 | 1992-03-19 | 1992-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-18 | 1996-03-19 | 1996-09-18 | $7700.00 | Window Closed / Lapsed |