US4401509A
Expired / Lapsed
US
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Composition and process for printed circuit etching using a sulfuric acid solution containing hydrogen peroxide
Assignee: FMC Corp
•
Filing: 1982-09-07
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Granted: 1983-08-30
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Expires: 2002-09-07
Abstract
Abstract Compositions are provided suitable for the etching of printed circuits from a laminate of copper metal and an etch resistant backing at a low hydrogen peroxide concentration and at a low temperature. The etching composition contains sulfuric acid, hydrogen peroxide as the oxidant, thiosulfate ion to counteract the depressing effect of chloride ion on the etch rate, an unsaturated organic hydroxy compound to stabilize the hydrogen peroxide in the presence of copper, and an aminomethylenephosphonic acid.
Inventors
- 👤 Richard Schellinger, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 08:39
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
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
60 words
An aqueous composition suitable for etching printed circuits even in the presence of more than 3 milligrams per liter of chloride ion comprising 2% to 20% sulfuric acid, 2% to 10% hydrogen peroxide, 0.1% to 0.4% of an aminomethylenephosphonic acid, 0.5% to 0.1% thiosulfate ion supplied as a thiosulfate salt, and 0.005% to 0.05% of an unsaturated organic hydroxy compound.
Claim 2
Dependent Claim
60 words
An aqueous composition suitable for etching printed circuits even in the presence of more than 3 milligrams per liter of chloride ion comprising 2% to 20% sulfuric acid, 2% to 10% hydrogen peroxide, 0.1% to 0.4% of an aminomethylenephosphonic acid, 0.5% to 0.1% thiosulfate ion supplied as a thiosulfate salt, and 0.005% to 0.05% of an unsaturated organic hydroxy compound.
Claim 3
Dependent Claim
43 words
The composition of claim 1 containing 5% to 12% sulfuric acid, 2% to 5% hydrogen peroxide, the thiosulfate salt is selected from the group consisting of alkali metal thiosulfates, alkaline earth thiosulfates and ammonium thiosulfates, and the unsaturated organic hydroxy compound is phenol.
Claim 4
Dependent Claim
29 words
The composition of claim 1 or 2 wherein the aminomethylenephosphonic acid is selected from the group consisting of amino tris(methylenephosphonic acid), ethylenediamine tetra(methylenephosphonic acid), and mixtures of the two.
Claim 5
Dependent Claim
23 words
The composition of claim 3 containing as the aminomethylenephosphonic acid 0.06% to 0.08% amino tris(methylenephosphonic acid), and 0.036% to 0.048% ethylenediamine tetra(methylenephosphonic acid).
Claim 6
Dependent Claim
67 words
In the process of etching printed circuits with 2% to 20% sulfuric acid etchant using as the oxidant 2% to 10% hydrogen peroxide and 0.05% to 0.1% thiosulfate ion, and 0.005% to 0.5% of an unsaturated hydroxy compound, the improvement comprising the presence in the etchant of 0.01% to 0.4% of an aminomethylenephosphonic acid and maintaining the temperature of the etchant at 35° C. to 45° C.
Claim 7
Dependent Claim
67 words
In the process of etching printed circuits with 2% to 20% sulfuric acid etchant using as the oxidant 2% to 10% hydrogen peroxide and 0.05% to 0.1% thiosulfate ion, and 0.005% to 0.5% of an unsaturated hydroxy compound, the improvement comprising the presence in the etchant of 0.01% to 0.4% of an aminomethylenephosphonic acid and maintaining the temperature of the etchant at 35° C. to 45° C.
Claim 8
Dependent Claim
27 words
The process of claim 5 wherein the aminomethylenephosphonic acid is selected from the group consisting of amino tris(methylenephosphonic acid), ethylenediamine tetra(methylenephosphonic acid), and mixtures of the two.
Claim 9
Dependent Claim
12 words
The process of claim 6 wherein the unsaturated hydroxy compound is phenol.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-08-29 | 1987-02-28 | 1987-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-29 | 1991-02-28 | 1991-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-29 | 1995-02-28 | 1995-08-30 | $7700.00 | Window Closed / Lapsed |