US3567533A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tin solder coated with chromium as a mask for etching a metal base
Assignee: FMC Corp
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Filing: 1969-02-20
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Granted: 1971-03-02
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Expires: 1989-02-20
Abstract
Abstract A METHOD OF ETCHING A METAL WORKPIECE IS DESCRIBED, WHICH CARRIES A TIN RESIST (OR A TIN-COATED SOLDER RESIST), A CHROMATE COATING IS PROVIDED OVER THE RESIST, AND THE METAL WORKPIECE IS ETCHED WITH AN AQUEOUS ETCHANT SUCH AS A PEROXYSULFATE CONTAINING PHOSPHORIC ACID OR A SODIUM CHLORITE-AMMONIUM HYDROXIDE SOLUTION OR A CHROMIC-SULFURIC ACID BATH TO DISSOLVE THE METAL FREE OF RESIST, THUS PRODUCING BRIGHT, SMOOTH AND ELECTRICALLY CLEAN RELIEFS HAVING SHARP PATTERN DEFINITION ON THE METAL WORKPIECE.
Inventors
- 👤 John S C Chiang
- 👤 Joseph T Mcmanamon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:28
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/02; H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/061; H05K3/062; H05K2201/00; H05K2201/01; H05K2201/0137; H05K2201/0175; H05K2201/03; H05K2201/0302; H05K2201/0305; H05K3/067
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) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |