US4221925A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Printed circuit board
Assignee: AT&T Inc
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Filing: 1978-09-18
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Granted: 1980-09-09
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Expires: 1998-09-18
Abstract
Abstract A printed circuit board is disclosed which comprises a metal substrate having a first coating thereon and through holes through said coating and substrate with non-linear, undercut walls and a dielectric film coating over said first coating and said non-linear, undercut walls of said through hole. Electrical circuitry is then formed on the dielectric coat in conjunction with the through hole.
Inventors
- 👤 Donald W. Finley
- 👤 Robert B. Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:32
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/44; H05K3/445; H05K2201/00; H05K2201/01; H05K2201/0183; H05K2201/0195; H05K2201/09; H05K2201/09209; H05K2201/095; H05K2201/09581; H05K2201/09818; H05K2201/09827; H05K2203/00; H05K2203/03; H05K2203/0323; H05K2203/05; H05K2203/0562; H05K2203/0571; H05K2203/10; H05K2203/105; H05K2203/13; H05K2203/1333; H05K2203/1355; H05K2203/14; H05K2203/1438; H05K3/02; H05K3/06; H05K3/061
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
79 words
A printed circuit board comprising: (a) a 1-7 mil thick metal substrate having a first coating thereon and a through hole with non-linear, undercut walls in said first coating and substrate wherein said undercut is from about 1 to about 3 mils; and (b) a dielectric film coating said first coating and said non-linear undercut walls of said through hole, said dielectric film having a thickness so as to resist dielectric breakdown at an applied voltage of 1500 volts.
Claim 2
Dependent Claim
79 words
A printed circuit board comprising: (a) a 1-7 mil thick metal substrate having a first coating thereon and a through hole with non-linear, undercut walls in said first coating and substrate wherein said undercut is from about 1 to about 3 mils; and (b) a dielectric film coating said first coating and said non-linear undercut walls of said through hole, said dielectric film having a thickness so as to resist dielectric breakdown at an applied voltage of 1500 volts.
Claim 3
Dependent Claim
43 words
The printed circuit board as defined in claim 1 wherein said dielectric coat has a through hole edge coverage of at least about 40 percent in thickness of the principal thickness of said dielectric coat on the principal surfaces of said first coating.
Claim 4
Dependent Claim
19 words
The printed circuit board as defined in claim 2 which further comprises a conductive pattern on said dielectric coat.
Claim 5
Dependent Claim
19 words
The printed circuit board as defined in claim 2 which further comprises a dielectric topcoat on said dielectric coat.
Claim 6
Dependent Claim
19 words
The printed circuit board as defined in claim 4 which further comprises a conductive circuit pattern on said topcoat.
Claim 7
Dependent Claim
17 words
The printed circuit board defined in claim 1 wherein said first coating is an etch resist coating.
Claim 8
Dependent Claim
30 words
The printed circuit board as defined in claim 2 wherein said dielectric coat has a glass plate flow value measured at 150° C. of about 0.1 to about 0.65 centimeters.
Claim 9
Dependent Claim
30 words
The printed circuit board as defined in claim 4 wherein said topcoat has a glass plate flow value measured at 150° C. of from about 1.2 to about 3.5 centimeters.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-09 | 1984-03-10 | 1984-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-09 | 1988-03-10 | 1988-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-09 | 1992-03-10 | 1992-09-09 | $7700.00 | Window Closed / Lapsed |