US3779877A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrolytic etching of aluminum foil
Assignee: Sprague Electric Co
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Filing: 1972-02-22
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Granted: 1973-12-18
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Expires: 1992-02-22
Abstract
Abstract A two stage electro-etch for increasing the effective surface area of high voltage aluminum foil comprises a first electro-etch in an alkali metal halide, preferably sodium chloride, followed by a second electro-etch in a neutral solution of a nitrate salt. The results produced with this process compare most favorably with the most advantageous processes known to the art today, and foils etched therein are less expensive to produce.
Inventors
- 👤 R Alwitt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:31
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/055; C; C25; C25F; C25F3/00; C25F3/02; C25F3/04; C25F7/00
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
24 words
The method of claim 1 wherein said alkali metal halide is sodium chloride and said neutral nitrate solution is a neutral sodium nitrate solution.
Claim 2
Dependent Claim
17 words
The method of claim 1 wherein the aluminum foil has a purity of at least 99.97 percent.
Claim 3
Independent Claim
65 words
A method for electrolytically etching electrolytic capacitor grade aluminum foil of at least 99.97 percent purity comprising the combination of first electrolytically etching the foil in aqueous sodium chloride solution, and subsequently electrolytically etching the foil in a neutral solution of 100g/liter of sodium nitrate at a temperature of 97*C and a current density of 1.7 amps/in2, said foil is etched therein at 4.27 amp-min/in2.
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) | 1976-12-17 | 1977-06-18 | 1977-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-17 | 1981-06-18 | 1981-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-17 | 1985-06-18 | 1985-12-18 | $7700.00 | Window Closed / Lapsed |