Patent US3671344A successfully refreshed from Google Patents.
US3671344A
Expired / Lapsed
US
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Process of etching metal with ammonium persulfate with recovery and recycling
Assignee: FMC Corp
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Filing: 1970-12-04
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Granted: 1972-06-20
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Expires: 1990-12-04
Abstract
Abstract PROCESS FOR ETCHING COPPER WITH AN AQUEOUS PERSULFATE SOLUTION, IN WHICH THE ETCHING SOLUTION IS REPEATEDLY REACTIVATED OVER AN EXTENDED PERIOD OF TIME BY REPEATED REMOVAL OF METAL SULFATE VALUES AND AMMONIUM SULFATE AND IN WHICH SUBSTANTIAL HYDROLYSIS OF THE PERSULFATE OCCURS DURING SAID EXTENDED PERIOD. A COMPOUND YIELDING AN ORTHOPHOSPHATE ION IS ADDED TO THE COMPOSITION OF THE ETCHING SOLUTION DURING THIS PERIOD TO MAINTAIN THE TOTAL PHOSPHATE ION CONCENTRATION AT 0.1 TO 0.35 M/1. AND AT A PH OF 1.2 TO 1.8.
Inventors
- 👤 John S C Chiang
- 👤 Bernard J Hogya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:38
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/18
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |