Calibration of electromigration reliability of flip-chip packages by electrothermal coupling analysis

Electromigration reliability of solder interconnects is dominated by current density and temperature inside the interconnects. For flip-chip packages, current densities around the regions where the traces connect a solder bump increase significantly due to the differences in feature sizes and electric resistivities between the solder bump and its adjacent traces. This current-crowding effect along with induced Joule heating accelerates electromigration failures. In this paper, the effects of current crowding and Joule heating in a flip-chip package are examined and quantified by three-dimensional electrothermal coupling analysis. We apply a volumetric averaging technique to cope with the current-crowding singularity. The volumetrically averaged current density and the maximum temperature in a solder bump are integrated into Black’s equation to calibrate the experimental electromigration fatigue lives.