US4145460A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating a printed circuit board with etched through holes
Assignee: AT&T Inc
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Filing: 1977-06-27
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Granted: 1979-03-20
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Expires: 1997-06-27
Abstract
Abstract A method of fabricating a printed circuit board is disclosed. The method comprises forming a patterned etch resist layer on a metal substrate and selectively etching the substrate to form a through hole with non-linear undercut walls. The etched metal substrate having the resist layer thereon is then coated with a dielectric powder to form a dielectric coat on the substrate having a sufficient through hole edge coverage.
Inventors
- 👤 Donald W. Finley
- 👤 Robert B. Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:17
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/44; H05K3/445; H05K2201/00; H05K2201/01; H05K2201/0183; H05K2201/0195; H05K2203/00; H05K2203/03; H05K2203/0323; H05K3/02; H05K3/06; H05K3/061; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49124; Y10T29/49155; Y10T29/49156
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
75 words
A method of preparing a printed wiring board, which comprises: (a) forming a patterned etch resist layer on a metal substrate; (b) selectively etching said metal substrate, having a thickness of from about 1 to about 7 mils to form a through hole with non-linear, undercut walls; and (c) coating said etched substrate having said resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient through hole edge coverage.
Claim 2
Independent Claim
75 words
A method of preparing a printed wiring board, which comprises: (a) forming a patterned etch resist layer on a metal substrate; (b) selectively etching said metal substrate, having a thickness of from about 1 to about 7 mils to form a through hole with non-linear, undercut walls; and (c) coating said etched substrate having said resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient through hole edge coverage.
Claim 3
Dependent Claim
27 words
The method as defined in claim 1 wherein said edge coverage is at least about 40 percent in thickness of the principal thickness of said dielectric coat.
Claim 4
Dependent Claim
23 words
The method as defined in claim 2 which further comprises coating said dielectric coated substrate with a second powder to form a topcoat.
Claim 5
Dependent Claim
17 words
The method as defined in claim 2 which further comprises forming electrical circuitry on said dielectric coat.
Claim 6
Dependent Claim
52 words
The method as defined in claim 1 wherein in step (a) a surface of said metal substrate is selectively coated with an etch resistant pattern to delineate an uncoated surface pattern corresponding to said through hole, and said selectively coated surface is exposed to an etchant to etch said uncoated surface pattern.
Claim 7
Dependent Claim
16 words
The method as defined in claim 3 which further comprises forming electrical circuitry on said topcoat.
Claim 8
Independent Claim
97 words
A method of fabricating a printed wiring board, which comprises: (a) selectively etching a metal substrate, having a thickness of from about 1 to about 7 mils, and having a patterned etch resist layer thereon, to form a through hole with non-linear, undercut walls; (b) coating said substrate and said etch resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient edge coverage; (c) coating said dielectric-coated substrate with a second powder to form a suitable topcoat; and (d) forming electrical circuitry on said topcoat in conjunction with said through hole.
Claim 9
Independent Claim
97 words
A method of fabricating a printed wiring board, which comprises: (a) selectively etching a metal substrate, having a thickness of from about 1 to about 7 mils, and having a patterned etch resist layer thereon, to form a through hole with non-linear, undercut walls; (b) coating said substrate and said etch resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient edge coverage; (c) coating said dielectric-coated substrate with a second powder to form a suitable topcoat; and (d) forming electrical circuitry on said topcoat in conjunction with said through hole.
Claim 10
Dependent Claim
52 words
The method as defined in claim 7 wherein in step (a) a surface of said metal substrate is selectively coated with an etch resistant pattern to delineate an uncoated surface pattern corresponding to said through hole, and said selectively coated surface is exposed to an etchant to etch said uncoated surface pattern.
Claim 11
Independent Claim
64 words
A method of preparing a printed wiring board, which comprises: (a) forming a patterned etch resist layer on a metal substrate; (b) selectively etching said metal substrate to form a through hole with non-linear, undercut walls; and (c) coating said etched substrate having said resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient through hole edge coverage.
Claim 12
Independent Claim
64 words
A method of preparing a printed wiring board, which comprises: (a) forming a patterned etch resist layer on a metal substrate; (b) selectively etching said metal substrate to form a through hole with non-linear, undercut walls; and (c) coating said etched substrate having said resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient through hole edge coverage.
Claim 13
Independent Claim
17 words
The method as defined in claims 9 which further comprises forming electrical circuitry on said dielectric coat.
Claim 14
Dependent Claim
26 words
The method as defined in claim 9 wherein said edge coverage is at least about 40% in thickness of the principal thickness of said dielectric coat.
Claim 15
Dependent Claim
22 words
The method as defined in claim 11 which further comprises coating said dielectric-coated substrate with a second powder to form a topcoat.
Claim 16
Independent Claim
89 words
A method of fabricating a printed wiring board, which comprises: (a) forming a patterned etch resist layer on a metal substrate; (b) selectively etching a metal substrate to form a through hole with non-linear, undercut walls; (c) coating said substrate and said etch resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient edge coverage; (d) coating said dielectric-coated substrate with a second powder to form a suitable topcoat; and (e) forming electrical circuitry on said topcoat in conjunction with said through hole.
Claim 17
Independent Claim
89 words
A method of fabricating a printed wiring board, which comprises: (a) forming a patterned etch resist layer on a metal substrate; (b) selectively etching a metal substrate to form a through hole with non-linear, undercut walls; (c) coating said substrate and said etch resist layer thereon with a dielectric powder to form a dielectric coat thereon having a sufficient edge coverage; (d) coating said dielectric-coated substrate with a second powder to form a suitable topcoat; and (e) forming electrical circuitry on said topcoat in conjunction with said through hole.
Claim 18
Dependent Claim
26 words
The method as defined in claim 13 wherein said edge coverage is at least about 40% in thickness of the principal thickness of said dielectric coat.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-03-19 | 1982-09-18 | 1983-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-19 | 1986-09-18 | 1987-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-19 | 1990-09-18 | 1991-03-20 | $7700.00 | Window Closed / Lapsed |