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.

Abstract: A composition for stripping solder and tin from a copper substrate having an extended life is provided by the inclusion of a polyacrylamide in a peroxide-fluoride based stripping composition. The presence of the polyacrylamide minimizes the adverse effect of the stripping composition on the copper substrate of the material undergoing treatment.