Patent ID: 7279086

Claim:
A method for optimizing a range of useful current densities for electroplating of a gold-tin alloy deposit from an electroplating solution, which comprises: formulating the electroplating solution to consist of an aqueous solvent, a concentration of gold in the solution in the form of a solution soluble cyanide complex, a concentration of tin in the solution in the form of a solution soluble organotin complex; and as a sole alloy deposition agent in the solution 2,2′-dipyridyl at a concentration effective to allow codeposition of the gold and tin upon a suitable substrate in a gold-tin alloy deposit containing between 60 and 95% gold with the balance being essentially tin, and optionally with a grain refining agent; and electroplating the gold-tin alloy deposit from the solution and onto the suitable substrate at a current density that is lower than would be possible in the absence of the 2,2′-dipyridyl, given the concentrations of the gold and tin in the solution.