Influence of electrochemical properties on electrochemical migration of SnPb and SnBi solders

SnPb solders have been widely used in many fields because of their excellent solderability. To respond to environmental and health concerns regarding SnPb solders, it is necessary to develop lead-free solder for electronic assembly. In this paper, the resistance to the electrochemical migration of eutectic SnPb and SnBi solder alloys was evaluated and analyzed to detect the difference in the electrochemical migration behavior between these solders by their electrochemical properties. Pb and Bi additions to a Sn-base solder improved the resistance to electrochemical migration because of enhanced polarization properties. The resistance was closely related to the cathodic deposition efficiency and the anodic dissolution behavior. In addition, the composition of the dendrite formed by the electrochemical migration was related to the standard electrode potential of the alloying element.