Characteristics of current crowding in flip-chip solder bumps

For a flip-chip package assembly, current crowding occurs in the vicinity of the locations where traces connect the solder bumps. This feature contributes significantly to the electromigration failure of the solder bumps. In this study the finite element analysis is performed to investigate characteristics of current crowding in a flip-chip solder bump subjected to a constant applied current. It is found that under such a condition, current crowding is induced solely by the structural geometry of the system. It is independent of the magnitude of the applied current. A volumetric averaging technique is also applied to cope with the current crowding singularity.