US4319972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
AC Etching of aluminum capacitor foil
Assignee: Sprague Electric Co
•
Filing: 1980-12-12
•
Granted: 1982-03-16
•
Expires: 2000-12-12
Abstract
Abstract Aluminum electrolytic capacitor foil is etched in a bath containing 0.75 to 1.8 M hydrochloric acid, 0.2 to 0.5 M aluminum chloride, and 0.05 to 0.4 M oxalic acid, while subjected to the action of alternating current of 16 to 36 Hz at 30 to 45 DEG C. in a single stage process.
Inventors
- 👤 Richard A. Bemis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:18
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/055; C; C25; C25F; C25F3/00; C25F3/02; C25F3/04
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
98 words
A process for etching aluminum electrolytic capacitor foil comprising subjecting the foil intermittently to the action of AC current at 16 to 36 Hz frequency in a single stage in an aqueous bath consisting essentially of 0.75 to 1.8 M hydrochloric acid, 0.2 to 0.5 M aluminum chloride, and 0.05 to 0.4 M oxalic acid and at a temperature of 30° to 45° C. by passing said foil between a pair of electrodes in an insulated frame during which etching takes place and then out of the field of said electrodes during which no electrochemical etching takes place.
Claim 2
Dependent Claim
98 words
A process for etching aluminum electrolytic capacitor foil comprising subjecting the foil intermittently to the action of AC current at 16 to 36 Hz frequency in a single stage in an aqueous bath consisting essentially of 0.75 to 1.8 M hydrochloric acid, 0.2 to 0.5 M aluminum chloride, and 0.05 to 0.4 M oxalic acid and at a temperature of 30° to 45° C. by passing said foil between a pair of electrodes in an insulated frame during which etching takes place and then out of the field of said electrodes during which no electrochemical etching takes place.
Claim 3
Dependent Claim
16 words
A process according to claim 1 wherein said aqueous bath is composed of substantially sulfate-free water.
Claim 4
Dependent Claim
35 words
A process according to claim 1 wherein said etch bath contains 1.25 M hydrochloric acid, 0.3 M aluminum chloride, and 0.3 M oxalic acid, said frequency is 26 Hz, and said temperature is 37° C.
References Cited (Backward Citations)
US1971761A
Cited
US2166990A
Cited
GB879768A
Cited
US3728237A
Cited
JPS4940537A
Cited
US4198278A
Cited
US4276129A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-03-15 | 1985-09-14 | 1986-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-03-15 | 1989-09-14 | 1990-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-03-15 | 1993-09-14 | 1994-03-16 | $7700.00 | Window Closed / Lapsed |