Lead-free tin - silver-based alloy or tin - copper-based alloy electroplating bath

摘要

PROBLEM TO BE SOLVED: To effectively prevent the substitute precipitation of silver or copper onto the surface of a tin or tin alloy anode at the time of plating treatment in a lead-free tin-silver based alloy or tin-copper based alloy electroplating bath.;SOLUTION: The lead-free tin-silver based alloy or tin-copper based alloy electroplating bath is obtained by adding a nonionic surfactant(s) selected from distyrenated phenol polyalkoxylate whose HLB(Hydrophile-Lypophile Balance) is 7.3 to 15.2, tristyrenated phenol polyalkoxylate whose HLB is 7.0 to 10.4, distyrenated cresol polyalkoxylate whose HLB is 8.2 to 15.0, and a tristyrenated cresol polyalkoxylate whose HLB is 7.7 to 13.9 to a tin-silver based alloy or tin-copper based alloy electroplating bath comprising a stannous salt, a silver or copper salt and various acids. Since the nonionic surfactant(s) with the specified chemical structural species having the prescribed HLB is selectively added, the substitute precipitation of silver or copper onto an anode surface is prevented, and the consumption of silver or copper in the bath is suppressed, thus the composition of the plating bath can be stabilized.;COPYRIGHT: (C)2006,JPO&NCIPI