Abstract
A unique characteristic of electronic solder joints is the passage of electric currents. In addition to the Joule heating, the passage of electric currents causes electromigration. Electromigration is the mass transport of metal atoms induced by current stressing, and it affects the microstructures of solders and the interfacial reactions at solder joints. Phase segregation, void formation and Sn extrusion in the solder matrix and other microstructural evolutions of solders have been observed. It has also been reported that the growth of intermetallic compounds would be either enhanced or retarded with the passage of electric currents. This chapter reviews the current understanding and observation of electromigration on electronic solder joints. In addition to experimental investigations, mathematical model descriptions of electromigration effects are summarized as well.