Patent US5244539A successfully refreshed from Google Patents.
US5244539A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Composition and method for stripping films from printed circuit boards
Assignee: Alpha Assembly Solutions Inc
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Filing: 1992-01-27
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Granted: 1993-09-14
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Expires: 2012-01-27
Abstract
Abstract A metal dissolving liquid and method for stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, including an aqueous solution of nitric acid in an amount sufficient to dissolve solder and tin, a source of ferric ions in an amount sufficient to dissolve tin-copper alloy, a source of halide ions in an amount sufficient to solubilize tin, and a source of ammonium ions in an amount sufficient, in combination with the halide ions, to solubilize the tin and substantially eliminate sludge formation, reduce attack on the copper substrate and provide a bright copper finish after solder removal. A liquid further including benzotriazole and urea in amounts not more than about 2% by weight of each. The liquid wherein the source of ammonium ions includes ammonium bicarbonate.
Inventors
- 👤 Peter T. McGrath
- 👤 Narendra K. Shah
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:34
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/44; H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/067
Claims Analysis
Total Claims: 44
Claim 1
Independent Claim
104 words
A metal dissolving liquid for stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, including in combination: an aqueous solution of nitric acid in an amount sufficient to dissolve solder and tin; a source of ferric ions in an amount sufficient to dissolve tin-copper alloy; a source of halide ions in an amount sufficient to solubilize tin; and a source of ammonium ions in an amount sufficient, in combination with said halide ions, to solubilize said tin and substantially eliminate sludge formation, reduce attack on said copper substrate and provide a bright copper finish after solder removal.
Claim 2
Dependent Claim
104 words
A metal dissolving liquid for stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, including in combination: an aqueous solution of nitric acid in an amount sufficient to dissolve solder and tin; a source of ferric ions in an amount sufficient to dissolve tin-copper alloy; a source of halide ions in an amount sufficient to solubilize tin; and a source of ammonium ions in an amount sufficient, in combination with said halide ions, to solubilize said tin and substantially eliminate sludge formation, reduce attack on said copper substrate and provide a bright copper finish after solder removal.
Claim 3
Dependent Claim
34 words
A liquid as defined in claim 1 including a material selected from the group consisting of benzotriazole, tolytriazole and combinations thereof in an amount not more than about 2% by weight of the liquid.
Claim 4
Dependent Claim
22 words
A liquid as defined in claim 2 including urea in an amount not more than about 2% by weight of the liquid.
Claim 5
Dependent Claim
16 words
A liquid as defined in claim 3 wherein said source of ammonium ions includes ammonium bicarbonate.
Claim 6
Dependent Claim
33 words
A liquid as defined in claim 1 wherein said source of halide ions is selected from the group consisting of HCl, HF, HBr, HI, NH 4 Cl, FeCl 3 , and combinations thereof.
Claim 7
Dependent Claim
79 words
A liquid as defined in claim 5 wherein said source of ammonium ions is selected from the group consisting of ammonium hydroxide, ammonium acetate, ammonium benzoate, ammonium bicarbonate, ammonium bifluoride, ammonium bitartrate, ammonium borate, ammonium bromide, ammonium carbomate, ammonium carbonate, ammonium ceric nitrate, ammonium chloride, ammonium citrate, ammonium cupric chloride, ammonium ferric citrate, ammonium ferric oxalate, ammonium ferric tartrate, ammonium fluoride, ammonium formate, ammonium iodide, ammonium lactate, ammonium nitrate, ammonium oxalate, ammonium salicylate, ammonium tartrate, urea, and combinations thereof.
Claim 8
Dependent Claim
45 words
A liquid as defined in claim 6 wherein said source of ferric ions is selected from the group consisting of ferric nitrate, ferric chloride, ferric acetate, ferric hydroxide, ferric lactate, ferric oxide and non sulfur bearing water soluble ferric salts of organic and inorganic nature.
Claim 9
Dependent Claim
72 words
A metal dissolving liquid for stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, including an aqueous solution of about 25 to 45 weight percent of 67% nitric acid aqueous solution, about 0.5 to 15 weight percent of a ferric ion source, about 0.5 to 6 weight percent of a halide ion source, and about 0.05 to 12 weight percent of an ammonium ion source.
Claim 10
Dependent Claim
72 words
A metal dissolving liquid for stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, including an aqueous solution of about 25 to 45 weight percent of 67% nitric acid aqueous solution, about 0.5 to 15 weight percent of a ferric ion source, about 0.5 to 6 weight percent of a halide ion source, and about 0.05 to 12 weight percent of an ammonium ion source.
Claim 11
Dependent Claim
34 words
A liquid as defined in claim 8 including a material selected from the group consisting of benzotriazole, tolytriazole and combinations thereof in an amount not more than about 2% by weight of the liquid.
Claim 12
Dependent Claim
22 words
A liquid as defined in claim 9 including urea in an amount not more than about 2% by weight of the liquid.
Claim 13
Dependent Claim
16 words
A liquid as defined in claim 10 wherein said source of ammonium ions includes ammonium bicarbonate.
Claim 14
Dependent Claim
33 words
A liquid as defined in claim 8 wherein said source of halide ions is selected from the group consisting of HCl, HF, HBr, HI, NH 4 Cl, FeCl 3 , and combinations thereof.
Claim 15
Dependent Claim
79 words
A liquid as defined in claim 12 wherein said source of ammonium ions is selected from the group consisting of ammonium hydroxide, ammonium acetate, ammonium benzoate, ammonium bicarbonate, ammonium bifluoride, ammonium bitartrate, ammonium borate, ammonium bromide, ammonium carbomate, ammonium carbonate, ammonium ceric nitrate, ammonium chloride, ammonium citrate, ammonium cupric chloride, ammonium ferric citrate, ammonium ferric oxalate, ammonium ferric tartrate, ammonium fluoride, ammonium formate, ammonium iodide, ammonium lactate, ammonium nitrate, ammonium oxalate, ammonium salicylate, ammonium tartrate, urea, and combinations thereof.
Claim 16
Dependent Claim
46 words
A liquid as defined in claim 13 wherein said source of ferric ions is selected from the group consisting of ferric nitrate, ferric chloride, ferric acetate, ferric hydroxide, ferric lactate, ferric oxide, and all non sulphur bearing water soluble ferric salts of organic and inorganic nature.
Claim 17
Dependent Claim
74 words
A metal dissolving liquid for stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, including an aqueous solution of about 25 to 45 weight percent of 67% nitric acid aqueous solution, about 0.5 to 15 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 6 weight percent of a halide ion source, and about 0 05 to 12 weight percent of an ammonium ion source.
Claim 18
Dependent Claim
74 words
A metal dissolving liquid for stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, including an aqueous solution of about 25 to 45 weight percent of 67% nitric acid aqueous solution, about 0.5 to 15 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 6 weight percent of a halide ion source, and about 0 05 to 12 weight percent of an ammonium ion source.
Claim 19
Dependent Claim
69 words
A metal dissolving liquid for stripping solder and the underlying tin-copper from the copper substrate of a printed / circuit board, including an aqueous solution of about 30 to 35 weight percent of 67% nitric acid aqueous solution, about 5 to 10 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 2 weight percent of hydrochloric acid, and about 0.5 to 12 weight percent of ammonium bicarbonate.
Claim 20
Dependent Claim
69 words
A metal dissolving liquid for stripping solder and the underlying tin-copper from the copper substrate of a printed / circuit board, including an aqueous solution of about 30 to 35 weight percent of 67% nitric acid aqueous solution, about 5 to 10 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 2 weight percent of hydrochloric acid, and about 0.5 to 12 weight percent of ammonium bicarbonate.
Claim 21
Dependent Claim
16 words
A liquid as defined in claim 16 including about 0.05 to 2 weight percent of benzotriazole.
Claim 22
Dependent Claim
15 words
A liquid as defined in claim 17 including about 0.05 to 2 weight percent urea.
Claim 23
Dependent Claim
113 words
In a method of stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, the steps of: providing an aqueous solution of nitric acid in an amount sufficient to dissolve solder and tin, a source of ferric ions in an amount sufficient to dissolve tin-copper alloy, a source of halide ions in an amount sufficient to solubilize tin, and a source of ammonium ions in an amount sufficient, in combination with said halide ions, to solubilize said tin and substantially eliminate sludge formation, reduce attack on said copper substrate and provide a bright copper finish after solder removal; and applying the solution to the printed circuit board.
Claim 24
Dependent Claim
113 words
In a method of stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, the steps of: providing an aqueous solution of nitric acid in an amount sufficient to dissolve solder and tin, a source of ferric ions in an amount sufficient to dissolve tin-copper alloy, a source of halide ions in an amount sufficient to solubilize tin, and a source of ammonium ions in an amount sufficient, in combination with said halide ions, to solubilize said tin and substantially eliminate sludge formation, reduce attack on said copper substrate and provide a bright copper finish after solder removal; and applying the solution to the printed circuit board.
Claim 25
Dependent Claim
37 words
The method as defined in claim 19 including a material in the solution selected from the group consisting of benzotriazole, tolytriazole and combinations thereof in an amount not more than about 2% by weight of the liquid.
Claim 26
Dependent Claim
25 words
The method as defined in claim 20 including urea in the solution in an amount not more than about 2% by weight of the liquid.
Claim 27
Dependent Claim
16 words
The method as defined in claim 21 wherein the source of ammonium ions includes ammonium bicarbonate.
Claim 28
Dependent Claim
33 words
The method as defined in claim 19 wherein the source of halide ions is selected from the group consisting of HCl, HF, HBr, HI, NH 4 Cl, FeCl 3 , and combinations thereof.
Claim 29
Dependent Claim
79 words
The method as defined in claim 23 wherein the source of ammonium ions is selected from the group consisting of ammonium hydroxide, ammonium acetate, ammonium benzoate, ammonium bicarbonate, ammonium bifluoride, ammonium bitartrate, ammonium borate, ammonium bromide, ammonium carbomate, ammonium carbonate, ammonium ceric nitrate, ammonium chloride, ammonium citrate, ammonium cupric chloride, ammonium ferric citrate, ammonium ferric oxalate, ammonium ferric tartrate, ammonium fluoride, ammonium formate, ammonium iodide, ammonium lactate, ammonium nitrate, ammonium oxalate, ammonium salicylate, ammonium tartrate, urea, and combinations thereof.
Claim 30
Dependent Claim
45 words
The method as defined in claim 24 wherein the source of ferric ions is selected from the group consisting of ferric nitrate, ferric chloride, ferric acetate, ferric hydroxide, ferric lactate, ferric oxide and non sulfur bearing water soluble ferric salts of organic and inorganic nature.
Claim 31
Dependent Claim
81 words
In a method of stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, the steps of: providing a aqueous solution of about 25 to 45 weight percent of 67% nitric acid, about 0.5 to 15 weight percent of a ferric ion source, about 0.5 to 6 weight percent of a halide ion source, and about 0.05 to 12 weight percent of an ammonium ion source; and applying the solution to the printed circuit board.
Claim 32
Dependent Claim
81 words
In a method of stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, the steps of: providing a aqueous solution of about 25 to 45 weight percent of 67% nitric acid, about 0.5 to 15 weight percent of a ferric ion source, about 0.5 to 6 weight percent of a halide ion source, and about 0.05 to 12 weight percent of an ammonium ion source; and applying the solution to the printed circuit board.
Claim 33
Dependent Claim
37 words
The method as defined in claim 26 including a material in the solution selected from the group consisting of benzotriazole, tolytriazole and combinations thereof in an amount not more than about 2% by weight of the liquid.
Claim 34
Dependent Claim
25 words
The method as defined in claim 27 including urea in the solution in an amount not more than about 2% by weight of the liquid.
Claim 35
Dependent Claim
16 words
The method as defined in claim 28 wherein the source of ammonium ions includes ammonium bicarbonate.
Claim 36
Dependent Claim
33 words
The method as defined in claim 26 wherein the source of halide ions is selected from the group consisting of HCl, HF, HBr, HI, NH 4 Cl, FeCl 3 , and combinations thereof.
Claim 37
Dependent Claim
79 words
The method as defined in claim 30 wherein the source of ammonium ions is selected from the group consisting of ammonium hydroxide, ammonium acetate, ammonium benzoate, ammonium bicarbonate, ammonium bifluoride, ammonium bitartrate, ammonium borate, ammonium bromide, ammonium carbomate, ammonium carbonate, ammonium ceric nitrate, ammonium chloride, ammonium citrate, ammonium cupric chloride, ammonium ferric citrate, ammonium ferric oxalate, ammonium ferric tartrate, ammonium fluoride, ammonium formate, ammonium iodide, ammonium lactate, ammonium nitrate, ammonium oxalate, ammonium salicylate, ammonium tartrate, urea, and combinations thereof.
Claim 38
Dependent Claim
46 words
The method as defined in claim 31 wherein the source of ferric ions is selected from the group consisting of ferric nitrate, ferric chloride, ferric acetate, ferric hydroxide, ferric lactate, ferric oxide, and all non sulphur bearing water soluble ferric salts of organic and inorganic nature.
Claim 39
Dependent Claim
84 words
In a method of stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, the steps of: providing an aqueous solution of about 25 to 45 weight percent of 67% nitric acid aqueous solution, about 0.5 to 15 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 6 weight percent of a halide ion source, and about 0.05 to 12 weight percent of an ammonium ion source; and applying the solution to the printed circuit board.
Claim 40
Dependent Claim
84 words
In a method of stripping solder and the underlying tin-copper alloy from the copper substrate of a printed circuit board, the steps of: providing an aqueous solution of about 25 to 45 weight percent of 67% nitric acid aqueous solution, about 0.5 to 15 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 6 weight percent of a halide ion source, and about 0.05 to 12 weight percent of an ammonium ion source; and applying the solution to the printed circuit board.
Claim 41
Dependent Claim
79 words
In a method of stripping solder and the underlying tin-copper from the copper substrate of a printed circuit board, the steps of: providing an aqueous solution of about 30 to 35 weight percent of 67% nitric acid aqueous solution, about 5 to 10 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 2 weight percent of hydrochloric acid, and about 0.5 to 12 weight percent of ammonium bicarbonate; and applying the solution to the printed circuit board.
Claim 42
Dependent Claim
79 words
In a method of stripping solder and the underlying tin-copper from the copper substrate of a printed circuit board, the steps of: providing an aqueous solution of about 30 to 35 weight percent of 67% nitric acid aqueous solution, about 5 to 10 weight percent of 45% ferric nitrate aqueous solution, about 0.5 to 2 weight percent of hydrochloric acid, and about 0.5 to 12 weight percent of ammonium bicarbonate; and applying the solution to the printed circuit board.
Claim 43
Dependent Claim
19 words
The method as defined in claim 34 including about 0.05 to 2 weight percent of benzotriazole in the solution.
Claim 44
Dependent Claim
18 words
The method as defined in claim 35 including about 0.05 to 2 weight percent urea in the solution.
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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) | 1996-09-13 | 1997-03-15 | 1997-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-13 | 2001-03-15 | 2001-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-09-13 | 2005-03-15 | 2005-09-14 | $7700.00 | Window Closed / Lapsed |