US4597828A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing printed circuit boards
Assignee: Firan Corp
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Filing: 1985-03-25
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Granted: 1986-07-01
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Expires: 2005-03-25
Abstract
Abstract In order to enable fine traces to be obtained on printed circuit boards without excessive undercutting, while maintaining a high degree of adhesion, an unclad FRA board is provided with a surface butter coat which is etched to form a microporous surface layer. This layer is subjected to treatment in a plasma additively reactive with surface groups of the butter coat resin to provide modified groups promoting adherence to a thin metallization layer of vacuum deposited copper. The metallization layer is selectively electroplated to form the desired circuit pattern, and the unplated areas of the metallization layer are etched away.
Inventors
- 👤 Jehane Tadros
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:26
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/38; H05K3/381; H05K2201/00; H05K2201/02; H05K2201/0203; H05K2201/0206; H05K2201/0209; H05K2203/00; H05K2203/07; H05K2203/0779; H05K2203/0783; H05K2203/09; H05K2203/095; H05K2203/11; H05K2203/1105; H05K3/10; H05K3/108; H05K3/386; H05K3/388
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
120 words
A method of preparing a printed circuit board comprising etching the external surface of a synthetic resin substrate board without metal cladding to provide a microporous structure in surface layers of the board which are free of fibrous reinforcement, freeing said surface layers of etchant residues, subjecting said surface to a plasma treatment in a plasma additively reactive with surface groups of the resin to provide modified surface groups promoting adherence to a metallization layer, metallizing the plasma treated surfaces by vacuum deposition or sputtering to provide a thin layer of copper, selectively electroplating the copper layer with a much thicker layer of copper in accordance with a desired circuit pattern, and etching away unplated areas of the metallization layer.
Claim 2
Independent Claim
120 words
A method of preparing a printed circuit board comprising etching the external surface of a synthetic resin substrate board without metal cladding to provide a microporous structure in surface layers of the board which are free of fibrous reinforcement, freeing said surface layers of etchant residues, subjecting said surface to a plasma treatment in a plasma additively reactive with surface groups of the resin to provide modified surface groups promoting adherence to a metallization layer, metallizing the plasma treated surfaces by vacuum deposition or sputtering to provide a thin layer of copper, selectively electroplating the copper layer with a much thicker layer of copper in accordance with a desired circuit pattern, and etching away unplated areas of the metallization layer.
Claim 3
Dependent Claim
14 words
A method according to claim 1, wherein the synthetic resin is an epoxy resin.
Claim 4
Dependent Claim
23 words
A method according to claim 2, wherein the board is a fibre reinforced laminate having a surface butter coat free of fibrous reinforcement.
Claim 5
Dependent Claim
22 words
A method according to claim 3, wherein the surface layers of the board are provided with said hydrophilic microporous structure by etching.
Claim 6
Dependent Claim
18 words
A method according to claim 4, wherein the surface layers are modified to improve their susceptibility to etching.
Claim 7
Dependent Claim
28 words
A method according to claim 5, wherein the surface layers are modified by incorporating a filler in the butter coat having an increased susceptibility to the etchant used.
Claim 8
Dependent Claim
18 words
A method according to claim 5, wherein the surface layers are treated with a swellant prior to etching.
Claim 9
Dependent Claim
18 words
A process according to claim 3, wherein the plasma used in the plasma treatment is an ammonia plasma.
Claim 10
Dependent Claim
20 words
A process according to claim 3, wherein the plasma used in the plasma treatment is a nitrogen and hydrogen plasma.
Claim 11
Dependent Claim
19 words
A process according to claim 3, wherein the plasma used in the plasma treatment is a diamino propane plasma.
Claim 12
Dependent Claim
25 words
A process according to claim 3, wherein the plasma used in the plasma treatment is oxgen plasma excited by direct current using a copper cathode.
Claim 13
Dependent Claim
19 words
A process according to claim 11, wherein a thin film of chromium is applied prior to the metallization layer.
Claim 14
Dependent Claim
21 words
A process according to claim 1, wherein the finished board is subjected to an annealing heat treatment to relieve stresses therein.
Claim 15
Dependent Claim
27 words
A process according to claim 1, wherein the etching treatment is such as to provide a pore size of about 5 microns in the microporous surface layers.
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) | 1989-06-30 | 1989-12-30 | 1990-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-30 | 1993-12-30 | 1994-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-30 | 1997-12-30 | 1998-07-01 | $7700.00 | Window Closed / Lapsed |