A process for forming a solder bump on an under bump metal structure in the manufacture of a microelectronic device comprising exposing the under bump metal structure to an electrolytic bath comprising a source of Sn2+ ions, a source of Ag+ ions, a thiourea compound and/or a quaternary ammonium surfactant;...http://www.google.se/patents/US20070037377?utm_source=gb-gplus-sharePatent US20070037377 - TIN-SILVER SOLDER BUMPING IN ELECTRONICS MANUFACTURE
