Adhesive bonding and miscellaneous chemical manufacture – Delaminating processes adapted for specified product – Delaminating in preparation for post processing recycling step
Patent
1992-01-27
1993-09-14
Powell, William A.
Adhesive bonding and miscellaneous chemical manufacture
Delaminating processes adapted for specified product
Delaminating in preparation for post processing recycling step
134 2, 134 3, 156664, 156666, 156903, 252 792, 252 793, 252 794, B44C 122, C23F 100, C09K 1304, C09K 1306
Patent
active
052445399
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.
REFERENCES:
patent: 4713144 (1987-12-01), Schiller
patent: 4921571 (1990-05-01), Kukanskis et al.
patent: 4957653 (1990-09-01), Cordani
patent: 5017267 (1991-05-01), Cordani
patent: 5035749 (1991-07-01), Haruta et al.
McGrath Peter T.
Shah Narendra K.
Ardrox Inc.
Powell William A.
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