Patent US3674492A successfully refreshed from Google Patents.
US3674492A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laminar photomask
Assignee: AT&T Inc
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Filing: 1970-12-09
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Granted: 1972-07-04
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Expires: 1990-12-09
Abstract
Abstract A HIGH SPEED, HIGH RESOLUTION LAMINAR PHOTOMASK IS OBTAINED BY COATING A TRANSPARENT SUBSTRATE MEMBER WITH CHROMIUM OR IRON OXIDE, A PHOTORESIST AND A THIN FILM OF A HIGH RESOLUTION PHOTOGRAPHIC EMULSION HAVING A THICKNESS OF THE ORDER OF 2.0 MICROMETERS. THE RESULTANT PHOTO- MASK IS FOUND TO ENHANCE THE SPEED OF CONVENTIONAL PHOTORESISTS AND TO INCREASE THE EFFECTIVE FIELD OF VIEW OF PROJECTION SYSTEMS BY REDUCING THE REQUIRED IMAGE MODUALTION.
Inventors
- 👤 Michael Richard Goldrick
- 👤 Robert Eugene Kerwin
- 👤 John George Skinner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:51
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/20; G03F7/2002; G03F7/2014; G03F7/2016; G03F1/00; G03F1/54
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) | 1975-07-04 | 1976-01-03 | 1976-07-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-04 | 1980-01-03 | 1980-07-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-04 | 1984-01-03 | 1984-07-04 | $7700.00 | Window Closed / Lapsed |