Failure modes of Sn3.0Ag0.5Cu flip-chip solder joints under current stress

Electromigration in flip chip solder joints of Sn3.0Ag0.5Cu has been studied at current density of 2.03times104 A/cm2 and the bump temperature was at 120 degC. Three potential failure modes were absolved and their corresponding microstructural mechanism was discussed in this paper. The pancake-type void is noticeable failure mode and dominated by current crowding. The continuous void at the cathode of contact interface between IMC and solder was also formed without current crowding. But the void has less area than the void at entire cathode contact interface to the Si Chip. The large area of IMC in left-hand section of solder joints distributed in solder joint uniquely. All of the unique microstructural evolution induced by electromigration concern the migration of atoms and vacancies in interconnects with unique geometry.