Effect of Ag and Cu content in Sn based Pb-free solder on electromigration

The effect of Ag and Cu concentrations on the electromigration of Pb-free solder was investigated. A nine cell experiment with Ag concentrations ranging from 1.2% to 2.2% and Cu concentrations ranging from 0.2 to 2.7% was conducted. Although the EM performance was found to be insensitive to the Ag and Cu concentrations in the range of the study, solder with 1.7% Cu showed the least Ag content dependence. EM failures occurred primarily on the substrate side. An effect of Sn grain texture with Ag and Cu concentrations was also observed.