US4632727A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Copper etching process and solution
Assignee: PSI Star Inc
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Filing: 1985-08-12
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Granted: 1986-12-30
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Expires: 2005-08-12
Abstract
Abstract Process and solution for etching copper, for example, to remove it from printed circuit boards. The etching is effected by an aqueous solution of nitric acid, a polymer which inhibits undercutting of the copper, a surfactant, and sulfuric acid and/or an alkane sulfonic acid such as methane sulfonic acid.
Inventors
- 👤 Norvell J. Nelson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:12
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/067; C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/18; H05K3/061; H05K3/062
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
36 words
In a process for etching copper: contacting the copper with an aqueous solution of nitric acid, a polymer, a surfactant, and a sulfonic acid of an alkane having no more than four carbon atoms per molecule.
Claim 2
Dependent Claim
36 words
In a process for etching copper: contacting the copper with an aqueous solution of nitric acid, a polymer, a surfactant, and a sulfonic acid of an alkane having no more than four carbon atoms per molecule.
Claim 3
Dependent Claim
13 words
The process of claim 1 wherein the sulfonic acid comprises methane sulfonic acid.
Claim 4
Dependent Claim
58 words
An aqueous solution for etching copper, containing nitric acid, a polymer, a surfactant, and an additional acid selected from the group consisting of sulfuric acid, a sulfonic acid of an alkane having no more than four carbon atoms per molecule and combinations thereof, the amounts of nitric acid and the additional acid in the solution being approximately equal.
Claim 5
Dependent Claim
58 words
An aqueous solution for etching copper, containing nitric acid, a polymer, a surfactant, and an additional acid selected from the group consisting of sulfuric acid, a sulfonic acid of an alkane having no more than four carbon atoms per molecule and combinations thereof, the amounts of nitric acid and the additional acid in the solution being approximately equal.
Claim 6
Dependent Claim
13 words
The solution of claim 3 wherein the sulfonic acid comprises methane sulfonic acid.
Claim 7
Dependent Claim
53 words
In a process for removing copper from a circuit board substrate with an etch resistant metal covering a portion of the copper to be retained: contacting the copper with an aqueous solution containing approximately equal amounts of nitric acid and sulfuric acid, a polymer which inhibits undercutting of the copper, and a surfactant.
Claim 8
Dependent Claim
53 words
In a process for removing copper from a circuit board substrate with an etch resistant metal covering a portion of the copper to be retained: contacting the copper with an aqueous solution containing approximately equal amounts of nitric acid and sulfuric acid, a polymer which inhibits undercutting of the copper, and a surfactant.
Claim 9
Dependent Claim
60 words
In a process for removing copper from a circuit board substrate with an etch resistant metal covering a portion of the copper to be retained: contacting the copper with an aqueous solution of nitric acid, sulfuric acid, a sulfonic acid having no more than four carbon atoms per molecule, a polymer which inhibits undercutting of the copper, and a surfactant.
Claim 10
Dependent Claim
60 words
In a process for removing copper from a circuit board substrate with an etch resistant metal covering a portion of the copper to be retained: contacting the copper with an aqueous solution of nitric acid, sulfuric acid, a sulfonic acid having no more than four carbon atoms per molecule, a polymer which inhibits undercutting of the copper, and a surfactant.
Claim 11
Dependent Claim
13 words
The process of claim 6 wherein the sulfonic acid comprises methane sulfonic acid.
Claim 12
Dependent Claim
58 words
In a process for removing copper from a circuit board substrate with an etch resistant metal covering a portion of the copper to be retained: contacting the copper with an aqueous solution of nitric acid, a sulfonic acid having no more than four carbon atoms per molecule, a polymer which inhibits undercutting of the copper, and a surfactant.
Claim 13
Dependent Claim
58 words
In a process for removing copper from a circuit board substrate with an etch resistant metal covering a portion of the copper to be retained: contacting the copper with an aqueous solution of nitric acid, a sulfonic acid having no more than four carbon atoms per molecule, a polymer which inhibits undercutting of the copper, and a surfactant.
Claim 14
Dependent Claim
13 words
The process of claim 8 wherein the sulfonic acid comprises methane sulfonic acid.
Claim 15
Dependent Claim
28 words
In a process of etching copper: contacting the copper with an aqueous solution containing approximately equal amounts of nitric acid and sulfuric acid, a polymer and a surfactant.
Claim 16
Dependent Claim
28 words
In a process of etching copper: contacting the copper with an aqueous solution containing approximately equal amounts of nitric acid and sulfuric acid, a polymer and a surfactant.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-12-29 | 1990-06-30 | 1990-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-29 | 1994-06-30 | 1994-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-29 | 1998-06-30 | 1998-12-30 | $7700.00 | Window Closed / Lapsed |