In flip-chip solder joints, Cu has been used as a underbump metallization (UBM) for its excellent wettability with solders. In addition, electromigration has become an crucial reliability concerns for fine-pitch flip chip solder joints. In this paper, 3-D finite element method was employed to simulate the current density distribution for the eutectic SnPb solder joints with 5 μm, 10 μm, and 20 urn thick Cu UBM. It was found that the thicker the UBM is, the lower the maximum current density inside the solder. The maximum current density decreased from 4.37 × 10 4 A/cm 2 to 7.54 × 10 3 A/cm 2 when the thickness of the UBM changed from 5 μm to 20 μm. Thicker Cu UBM can effectively relieve the current crowding effect inside the solder.
|Number of pages||5|
|Journal||Proceedings - Electronic Components and Technology Conference|
|State||Published - 19 Sep 2005|
|Event||55th Electronic Components and Technology Conference, ECTC - Lake Buena Vista, FL, United States|
Duration: 31 May 2005 → 4 Jun 2005