US4113579A
Expired / Lapsed
US
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Process for producing an aluminum electrolytic capacitor having a stable oxide film
Assignee: UNITED CHEMI-CON MANUFACTURING Inc
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Filing: 1977-04-28
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Granted: 1978-09-12
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Expires: 1997-04-28
Abstract
Abstract An electrolytic capacitor is provided with an electrode having a stable aluminum oxide dielectric by anodizing an aluminum foil in a process that includes depolarizing the foil in a bath containing a hydration inhibitor selected from tartrate or citrate or phosphate anions.
Inventors
- 👤 John J. Randall, Jr.
- 👤 Walter J. Bernard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:34
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/0029; H01G9/0032; C; C25; C25D; C25D11/00; C25D11/02; C25D11/04; C25D11/12; Y; Y10; Y10S; Y10S205/00; Y10S205/917
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
74 words
The process for producing an aluminum electrolytic capacitor having a stable oxide film comprising forming a hydrated oxide layer on an aluminum foil, and then anodizing said foil in a formation electrolyte containing borate anions, then depolarizing said anodized foil in a bath containing a hydration inhibitor selected from phosphate, borate, and alpha- or ortho- hydroxy carboxylic acid anions, the pH of said bath being between 2 and 7, and then reanodizing said foil.
Claim 2
Dependent Claim
74 words
The process for producing an aluminum electrolytic capacitor having a stable oxide film comprising forming a hydrated oxide layer on an aluminum foil, and then anodizing said foil in a formation electrolyte containing borate anions, then depolarizing said anodized foil in a bath containing a hydration inhibitor selected from phosphate, borate, and alpha- or ortho- hydroxy carboxylic acid anions, the pH of said bath being between 2 and 7, and then reanodizing said foil.
Claim 3
Dependent Claim
22 words
The process of claim 1 wherein said foil is etched, and said hydration inhibitor is selected from tartrate, citrate, and phosphate anions.
Claim 4
Dependent Claim
34 words
The process of claim 2 wherein said hydration inhibitor is selected from hydrogen, ammonium, sodium, and potassium cations with the proviso that when the anion is phosphate, the cation is ammonium, sodium, or potassium.
Claim 5
Dependent Claim
14 words
The process of claim 3 wherein said hydration inhibitor is 0.1 M diammonium citrate.
Claim 6
Dependent Claim
20 words
The process of claim 2 wherein said hydration inhibitor is present in a concentration of greater than 10 -5 M.
Claim 7
Dependent Claim
16 words
The process of claim 2 wherein the pH is in the range of 4 to 5.
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) | 1981-09-11 | 1982-03-13 | 1982-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-11 | 1986-03-13 | 1986-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-11 | 1990-03-13 | 1990-09-12 | $7700.00 | Window Closed / Lapsed |