Electromigration, fuse and thermo-mechanical performance of solder bump versus Cu pillar flip chip assemblies

Two different flip chip bump configurations have been investigated in terms of their thermo-mechanical, electromigration and fusing behaviour. Standard SAC (SnAgCu) solder bumps with a Ni/Au finish on the chip side are compared with Cu pillar bumps soldered with a thin layer of SnAg alloy. For the test structure, the flip chip assembly is integrated in a BGA package. Finite Element Modelling is used to support the experimental work and explain some of the conclusions.