US4470885A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for treating aluminum electrolytic capacitor foil
Assignee: Sprague Electric Co
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Filing: 1983-02-07
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Granted: 1984-09-11
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Expires: 2003-02-07
Abstract
Abstract Aluminum electrolytic capacitor foil is treated after etching but before anodizing by first contacting it with a phosphate solution and then heat treating for 30 to 90 seconds to form a thermal oxide layer of controlled thickness. On subsequent anodization, the thermal oxide layer modifies the barrier oxide layer increasing its dielectric strength and hence capacitance and also stabilizes the barrier oxide layer.
Inventors
- 👤 John J. Randall, Jr.
- 👤 Trung H. Nguyen
- 👤 Clinton E. Hutchins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:19
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; C; C23; C23C; C23C22/00; C23C22/73; C23C22/74; C25; C25D; C25D11/00; C25D11/02; C25D11/04; C25D11/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
89 words
A process for treating aluminum electrolytic capacitor foil comprising contacting said foil after etching with a solution containing 0.01 to 1.0 mole/liter of a soluble dihydrogen phosphate and having a pH of 4 to 6 and then heat treating said foil for between 30 and 90 seconds at between 590° and 630° C. to form a layer of thermal oxide of controlled thickness on said foil and then anodizing said foil producing a modified barrier layer oxide thus increasing capacitance of said foil and stabilizing said barrier layer oxide.
Claim 2
Dependent Claim
89 words
A process for treating aluminum electrolytic capacitor foil comprising contacting said foil after etching with a solution containing 0.01 to 1.0 mole/liter of a soluble dihydrogen phosphate and having a pH of 4 to 6 and then heat treating said foil for between 30 and 90 seconds at between 590° and 630° C. to form a layer of thermal oxide of controlled thickness on said foil and then anodizing said foil producing a modified barrier layer oxide thus increasing capacitance of said foil and stabilizing said barrier layer oxide.
Claim 3
Dependent Claim
16 words
A process according to claim 1 wherein said heat treating is carried out for 45 seconds.
Claim 4
Dependent Claim
17 words
A process according to claim 1 wherein said contacting is carried out at 50° to 85° C.
Claim 5
Dependent Claim
14 words
A process according to claim 1 wherein said dihydrogen phosphate is ammonium or sodium.
Claim 6
Dependent Claim
24 words
A process according to claim 4 wherein said phosphate solution contains 0.05 mole/liter ammonium phosphate and said contacting is carried out at 50° C.
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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) | 1987-09-11 | 1988-03-12 | 1988-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-11 | 1992-03-12 | 1992-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-11 | 1996-03-12 | 1996-09-11 | $7700.00 | Window Closed / Lapsed |