Solder stripping solution
AssigneeCircuit Chemistry Corporation
InventorJames J. Czaja
Life of this patent
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Abstract
Solder stripping solution having an extended life for stripping and removing tin-lead alloy solder or tin deposits from entire circuits or tabs with an insignificant amount of attack on the base epoxy laminate or underlay copper or nickel substrate while leaving a residue-free substrate surface. This solution can be utilized at room temperature or preferably slightly above, and has a prolonged useful life of weeks to months. The composition of the solution includes a hydroxyphenol in an aqueous solution of a nitro-substituted aromatic compound, an inorganic acid, and thiourea.
Claims16
Solution for the removal of tin or tin-lead alloy solder from a copper or nickel base, said solution comprising:
- (a) 20-150 g/l of a m-nitro substituted aromatic compound;
- (b) 0.5-10 g/l of a thiourea selected from a group of thiourea per se, an alkyl thiourea or an aromatic thiourea;
- (c) 0.1-50 percent by volume of an inorganic acid selected from a group including fluoboric acid, fluosilicic acid, sulfamic acid, or nitric acid;
- and,
- (d) 0.1-50.0 g/l of a hydroxyphenol providing extended life to the stripping solution.
Non-peroxide solder stripper solution comprising:
- (a) nitro-substituted aromatic compound of 20-150 g/l;
- (b) fluoborate compound of 0.1-750 g/l;
- (c) hydroxyphenol of 0.1-50 g/l;
- (d) ammonium compound of 0.1-300 g/l;
- (e) inorganic acid of 0.1-400 g/l;
- (f) thiourea of 0.1-30 g/l;
- (g) boric acid of 2-60 g/l;
- and
- (h) water to one liter.
Non-peroxide solder stripping solution comprising:
- (a) sodium m-nitrobenzenesulfonate of 80 g/l;
- (b) fluoboric acid of 276 g/l;
- (c) boric acid of 8 g/l;
- (d) 3-hydroxyphenol of 8 g/l;
- (e) ammonium nitrate of 36 g/l;
- (f) nitric acid of 90 ml/l;
- (g) thiourea of 14 g/l;
- (h) to one liter of water.
Dependencies are inferred from the claim text.