US4574031A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Additive processing electroless metal plating using aqueous photoresist
Assignee: AT&T Inc
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Filing: 1985-03-29
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Granted: 1986-03-04
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Expires: 2005-03-29
Abstract
Abstract In a method for making a printed circuit board employing an aqueous type photoresist and including etching of the substrate surface with chromic acid after application of the photoresist mask, chromium is washed from the surface with a reducing agent at a pH of </=10.
Inventors
- 👤 II John K. Dorey
- 👤 James T. Huneke
- 👤 Bruce S. Madsen
- 👤 Theodore F. Schaaf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:03
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/1601; C23C18/1603; C23C18/1605; C23C18/1607; C23C18/1608; C23C18/1633; C23C18/1646; C23C18/165; C23C18/1651; C23C18/18; C23C18/20; C23C18/2006; C23C18/2046; C23C18/2073; C23C18/2086; C23C18/22; C23C18/24; C23C18/26; C23C18/28; C23C18/285; C23C18/30; C23C18/31; C23C18/38; C23C18/40; H; H05; H05K; H05K3/00; H05K3/10; H05K3/18; H05K3/181; H05K3/182; H05K3/184; C23C18/1653; H05K2203/00; H05K2203/07; H05K2203/0779; H05K2203/0786; H05K2203/0789; H05K2203/0793; H05K2203/14; H05K2203/1415; H05K3/38; H05K3/381
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
103 words
A method for making a printed circuit including the steps of: (a) applying a photoresist mask to the surface of a substrate to delineate the desired pattern, said photoresist being soluble in an aqueous alkaline solution of pH >10; (b) treating the substrate with a chromic acid solution so as to etch the exposed substrate surface; (c) washing the substrate in a reducing media having a pH of ≦10 so as to reduce and remove chrome from the surface; (d) catalyze the surface of the substrate; and (e) electrolessly deposit a thin flash metal deposit from a hypophosphite type flash electroless plating solution.
Claim 2
Independent Claim
103 words
A method for making a printed circuit including the steps of: (a) applying a photoresist mask to the surface of a substrate to delineate the desired pattern, said photoresist being soluble in an aqueous alkaline solution of pH >10; (b) treating the substrate with a chromic acid solution so as to etch the exposed substrate surface; (c) washing the substrate in a reducing media having a pH of ≦10 so as to reduce and remove chrome from the surface; (d) catalyze the surface of the substrate; and (e) electrolessly deposit a thin flash metal deposit from a hypophosphite type flash electroless plating solution.
Claim 3
Dependent Claim
20 words
The method recited in claim 1, wherein the substrate is swelled by treatment with a swellant solution prior to etching.
Claim 4
Dependent Claim
29 words
The method recited in claim 2, wherein the substrate surface comprises an epoxy resin, the swellant is dimethylformamide and the chromic acid solution comprises chromium trioxide in sulfuric acid.
Claim 5
Dependent Claim
58 words
The method recited in claim 1, including the steps of stripping the photoresist mask subsequent to flash plating whereby any catalyst and flash plate overlying said mask are removed with the mask thereby leaving a flash plate pattern on the remaining portions of the substrate and subsequently plating additional conductor over the flash plate to a predetermined thickness.
Claim 6
Dependent Claim
20 words
The method recited in claim 4, wherein the subsequent plating over the flash plate is by means of electroless plating.
Claim 7
Dependent Claim
16 words
The method recited in claim 1, wherein the reducing media comprises a solution of sodium bisulfite.
Claim 8
Dependent Claim
25 words
The method recited in claim 1, wherein washing is performed by treatment with a sodium bisulfite reducing solution followed by rinsing with an HCl solution.
Claim 9
Dependent Claim
14 words
The method recited in claim 1, wherein the reducing media is a hydrazine solution.
Claim 10
Dependent Claim
13 words
The method recited in claim 8, wherein the hydrazine is mixed with HCl.
Claim 11
Dependent Claim
20 words
The method recited in claim 9, wherein washing includes an HCl solution rinse subsequent to treatment with the hydrazine solution.
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) | 1989-03-03 | 1989-09-02 | 1990-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-03 | 1993-09-02 | 1994-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-03 | 1997-09-02 | 1998-03-04 | $7700.00 | Window Closed / Lapsed |