US4911796A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Plated through-holes in a printed circuit board
Assignee: HC TANG & ASSOCIATES C/O NELSON C YEW STE 610 TOWER I CHEUNG SHA WAN PLAZA 833 CHEUNG SUA WAN RD KOWLOON HONG KONG
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Filing: 1988-03-23
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Granted: 1990-03-27
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Expires: 2008-03-23
Abstract
Abstract A process of forming plates through-holes in a printed circuit board involves placing a film of fluid ink having electrically conductive properties on a side wall of the hole, curing the film to a solid and electroplating a layer of metal on the conductive ink film. The conductive ink preferably is a composition including conductive particles such as carbon and silver flakes. The ink also preferably includes a thermosetting or radiation curable binder and a thinner. The film of ink is cured before the layer of metal is electroplated thereon. The plated through-hole is protected from the etchant when the conductors are etched by placing a radiation curable putty material into the hole, curing it, and then depositing a layer of resist on top of the cured putty and a conductive sheet clad to the substrate of the circuit board.
Inventors
- 👤 Ronald G. Reed
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 23:04
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/0008; H05K3/02; H05K3/06; H05K3/061; H05K2201/00; H05K2201/03; H05K2201/0332; H05K2201/0335; H05K2201/0355; H05K2201/09; H05K2201/09209; H05K2201/095; H05K2201/0959; H05K2201/09818; H05K2201/09981; H05K2203/00; H05K2203/01; H05K2203/0104; H05K2203/0126; H05K2203/013; H05K2203/0191; H05K2203/05; H05K2203/0548; H05K2203/0554; H05K2203/07; H05K2203/0756; H05K2203/0763; H05K2203/08; H05K2203/082; H05K3/0011; H05K3/0044; H05K3/0047; H05K3/40; H05K3/42; H05K3/423; H05K3/424; H05K3/425; H05K3/427
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
149 words
A process for electroplating a metallic layer on a side wall of a hold formed in a conductor clad board to produce a plated through-hole in a printed circuit board, comprising the steps of: coating the side wall of the hole with an excess of fluid ink having predetermined electrically conductive properties and predetermined surface tension and wetting characteristics, removing excess ink from the hole, the predetermined surface tension characteristics of the ink pulling the remaining ink into a relatively thin smooth and uniform film of fluid ink remaining in the hole upon removal of the excess ink, the predetermined wetting characteristics of the ink adhering the film substantially uniformly over the whole surface of the side wall of the hole, changing the ink in the film from a fluid to a substantial solid, and electroplating a metallic layer on the solid film of ink on the side wall.
Claim 2
Dependent Claim
149 words
A process for electroplating a metallic layer on a side wall of a hold formed in a conductor clad board to produce a plated through-hole in a printed circuit board, comprising the steps of: coating the side wall of the hole with an excess of fluid ink having predetermined electrically conductive properties and predetermined surface tension and wetting characteristics, removing excess ink from the hole, the predetermined surface tension characteristics of the ink pulling the remaining ink into a relatively thin smooth and uniform film of fluid ink remaining in the hole upon removal of the excess ink, the predetermined wetting characteristics of the ink adhering the film substantially uniformly over the whole surface of the side wall of the hole, changing the ink in the film from a fluid to a substantial solid, and electroplating a metallic layer on the solid film of ink on the side wall.
Claim 3
Dependent Claim
18 words
A process as defined in claim 1 wherein the conductive ink includes conductive carbon particles and silver flakes.
Claim 4
Dependent Claim
18 words
A process as defined in claim 2 wherein the conductive ink further includes a binder and a thinner.
Claim 5
Dependent Claim
24 words
A process as defined in claim 2 wherein the carbon particles and the silver flake are approximately equal by weight in the conductive ink.
Claim 6
Dependent Claim
24 words
A process as defined in claim 2 wherein the silver flake has a particle size of generally less than or equal to 2 microns.
Claim 7
Dependent Claim
29 words
A process as defined in claim 2 wherein the carbon particles are carbon black particles which have a particle size of generally less than or equal to 0.5 microns.
Claim 8
Dependent Claim
25 words
A process as defined in claim 3 further comprising: curing the binder of the conductive ink prior to electrolytically depositing the layer of metal thereon.
Claim 9
Dependent Claim
20 words
A process as defined in claim 7 wherein curing the binder is accomplished by applying radiant energy to the film.
Claim 10
Dependent Claim
31 words
A process as defined in claim 1 wherein the step of coating the side wall of the hole comprises spreading conductive ink into the hole from the surface of the board.
Claim 11
Dependent Claim
74 words
A process as defined in claim 9 wherein said conductor clad board includes a conductive sheet clad to an insulating substrate and a peel sheet releasably attached over a conductive sheet, and wherein said process further comprises: curing the binder of the conductive ink prior to electroplating the layer of metal thereon; and removing the peel sheet after the binder of the conductive ink has cured and before electroplating the layer of metal thereon.
Claim 12
Dependent Claim
51 words
A process as defined in claim 1 wherein said conductor clad board includes a conductive sheet clad to an insulating substrate and a peel sheet releasably attached over a conductive sheet, and wherein said process further comprises: removing the peel sheet after the excess ink has been removed from the hole.
Claim 13
Dependent Claim
132 words
A process for electroplating a metallic layer on a side wall of a hole formed in a conductor clad board to produce a plated through-hole in a printed circuit board, comprising the steps of: coating the side wall of the hole with a predetermined fluid ink having electrically conductive properties, removing any excess ink to leave a film of fluid ink adhering to the side wall of the hole, changing the ink in the film from a fluid to a substantial solid, electroplating a metallic layer on the solid film of ink on the side wall, filling holes with a radiation curable putty after the layer of metal has been electroplated on the side wall of the hole, and curing the putty by exposing it to radiation to create a hole plug.
Claim 14
Dependent Claim
132 words
A process for electroplating a metallic layer on a side wall of a hole formed in a conductor clad board to produce a plated through-hole in a printed circuit board, comprising the steps of: coating the side wall of the hole with a predetermined fluid ink having electrically conductive properties, removing any excess ink to leave a film of fluid ink adhering to the side wall of the hole, changing the ink in the film from a fluid to a substantial solid, electroplating a metallic layer on the solid film of ink on the side wall, filling holes with a radiation curable putty after the layer of metal has been electroplated on the side wall of the hole, and curing the putty by exposing it to radiation to create a hole plug.
Claim 15
Dependent Claim
35 words
A process as defined in claim 12 further comprising: depositing resist on the hole plug and the conductor clad to the board, and etching the conductor clad to the board to create a circuit pattern.
Claim 16
Dependent Claim
29 words
A process as defined in claim 1 wherein removing the excess conductive ink to leave the film comprises: subjecting the ink to fluid pressure to expell the excess ink.
References Cited (Backward Citations)
US3261769A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-26 | 1993-09-25 | 1994-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-26 | 1997-09-25 | 1998-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-26 | 2001-09-25 | 2002-03-27 | $7700.00 | Window Closed / Lapsed |