The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 14, 1993
Filed:
Jan. 27, 1992
Peter T McGrath, Wendelstein, DE;
Narendra K Shah, Mission Viejo, CA (US);
Ardrox, Inc., La Mirada, CA (US);
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.