Patent US1529561A successfully refreshed from Google Patents.
Patent US4437955A successfully refreshed from Google Patents.
US4437955A
Expired / Lapsed
US
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Combined AC and DC etching of aluminum foil
Assignee: Philips North America LLC
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Filing: 1983-07-05
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Granted: 1984-03-20
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Expires: 2003-07-05
Abstract
Abstract Aluminum foil exhibiting a good combination of capacitance and mechanical strength is produced by an etching procedure that includes the steps of AC pre-etching aluminum foil in an acid bath containing hydrochloric acid and then, without removing the hydrochloric acid from the foil, etching the foil with a high density DC while the foil is immersed in an aqueous solution of sodium chloride and sodium sulfate.
Inventors
- 👤 Jesse S. Shaffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:01
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/055; C; C25; C25F; C25F3/00; C25F3/02; C25F3/04; Y; Y10; Y10S; Y10S204/00; Y10S204/08; Y10T; Y10T428/00; Y10T428/12; Y10T428/12431
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
178 words
A process for the electrolytic etching of aluminum capacitor foil comprising pre-etching said foil by immersing said foil in a first aqueous electrolyte bath containing, by weight, from 1-6% of HCl, 0-2% of H 3 PO 4 and 0-2% of HNO 3 while being subjected to an AC of a current density of 0.1-2.0 amps/cm 2 and a frequency of 15-100 Hertz while said first electrolyte bath is maintained at a temperature of 30°-60° C. until a loss of weight of said foil of at least about 0.05 mg/cm 2 is achieved and then, without removing the HCl from said foil, etching said foil by immersing said foil in a second aqueous electrolyte bath containing, by weight, 18-26% of NaCl and either 0.3-2% of Na 2 SO 4 or 1-4% of boric acid while being subjected to DC of a current density of 2-5 amps/cm 2 while said second electrolyte bath is maintained at a temperature of about 80°-100° C. until a total loss of weight of said foil of at least about 7 mg/cm 2 is achieved.
Claim 2
Dependent Claim
178 words
A process for the electrolytic etching of aluminum capacitor foil comprising pre-etching said foil by immersing said foil in a first aqueous electrolyte bath containing, by weight, from 1-6% of HCl, 0-2% of H 3 PO 4 and 0-2% of HNO 3 while being subjected to an AC of a current density of 0.1-2.0 amps/cm 2 and a frequency of 15-100 Hertz while said first electrolyte bath is maintained at a temperature of 30°-60° C. until a loss of weight of said foil of at least about 0.05 mg/cm 2 is achieved and then, without removing the HCl from said foil, etching said foil by immersing said foil in a second aqueous electrolyte bath containing, by weight, 18-26% of NaCl and either 0.3-2% of Na 2 SO 4 or 1-4% of boric acid while being subjected to DC of a current density of 2-5 amps/cm 2 while said second electrolyte bath is maintained at a temperature of about 80°-100° C. until a total loss of weight of said foil of at least about 7 mg/cm 2 is achieved.
Claim 3
Dependent Claim
25 words
The process of claim 1 wherein the bath employed in the AC pre-etching step contains from 0.5-2% by weight of H 3 PO 4 .
Claim 4
Dependent Claim
46 words
The process of claim 2 wherein the pre-etch step is continued until a weight loss of the foil of about 0.05-2.0 mg/cm 2 is achieved and the etching step is continued until a total weight loss of said foil of about 7-14 mg/cm 2 is achieved.
Claim 5
Dependent Claim
17 words
Etched aluminum foil particularly adapted for use in electrolytic capacitors produced by the method of claim 1.
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) | 1987-03-20 | 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 |