US3702277A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for mask etching apparatus
Assignee: Zenith Electronics LLC
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Filing: 1970-09-23
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Granted: 1972-11-07
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Expires: 1990-09-23
Abstract
Abstract A mask etching apparatus has a succession of etching stations to which etchant is supplied from a common source through a closed circulating distribution system. Measuring devices monitor the etching process by measuring the hole size of the mask in process and develop a control potential through which the duration of the etching time is controlled in the carious stations. When no etching is to take place in a given station, a valve to that station is closed but a by-pass permitting a restricted flow of etchant continues circulation through the entire system.
Inventors
- 👤 Martin L Lerner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:16
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/02
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) | 1975-11-07 | 1976-05-08 | 1976-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-07 | 1980-05-08 | 1980-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-07 | 1984-05-08 | 1984-11-07 | $7700.00 | Window Closed / Lapsed |