US4437945A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for anodizing aluminum foil
Assignee: Sprague Electric Co
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Filing: 1983-08-31
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Granted: 1984-03-20
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Expires: 2003-08-31
Abstract
Abstract In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil and stabilization of the foil in alkaline borax baths, the foil is electrochemically anodized in an aqueous solution of monosodium phosphate having a pH of 3.5 to 5.0 as electrolyte. The anodization is interrupted for stabilization of the foil by passing it through a bath containing a borax solution having a pH of 8.5 to 9.5 at a temperature of above 80 DEG C., and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 550 V.
Inventors
- 👤 Mary A. Sells
- 👤 John W. Scott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:45
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/0029; H01G9/0032; C; C25; C25D; C25D11/00; C25D11/02; C25D11/04; C25D11/06; C25D11/08; C25D11/12; C25D11/18; C25D11/24
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
73 words
In an improved process for electrochemically anodizing aluminum electrolytic capacitor foil including the formation of a hydrous oxide layer on said foil before anodizing, then anodizing said foil and repeatedly interrupting said anodizing to subject the foil to a stabilizing treatment in a mildly alkaline borate bath of at least 80° C., the improvement comprising carrying out said anodizing in a bath containing monosodium phosphate and having a pH of 3.5 to 5.0.
Claim 2
Dependent Claim
73 words
In an improved process for electrochemically anodizing aluminum electrolytic capacitor foil including the formation of a hydrous oxide layer on said foil before anodizing, then anodizing said foil and repeatedly interrupting said anodizing to subject the foil to a stabilizing treatment in a mildly alkaline borate bath of at least 80° C., the improvement comprising carrying out said anodizing in a bath containing monosodium phosphate and having a pH of 3.5 to 5.0.
Claim 3
Dependent Claim
17 words
A process according to claim 1 wherein said pH is controlled by the addition of phosphoric acid.
Claim 4
Dependent Claim
17 words
A process according to claim 1 wherein the resistivity of said monophosphate is 400 to 1600 ohm-cm.
Claim 5
Dependent Claim
17 words
A process according to claim 1 wherein the concentration of said phosphate is 0.2 to 1.5 g/l.
Claim 6
Dependent Claim
19 words
A process according to claim 1 wherein said foil is anodized to a voltage of up to 550 V.
References Cited (Backward Citations)
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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) | 1987-03-20 | 1987-09-19 | 1988-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-20 | 1991-09-19 | 1992-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-20 | 1995-09-19 | 1996-03-20 | $7700.00 | Window Closed / Lapsed |