Reliability studies of Sn-Ag-Cu BGA solder joints on Ni/Cu/Au surface finish for SMAFTI packaging technology

A novel pad metal stack structure for wafer-level 3-D packaging technology with fine and thin interposer is proposed. The purpose of this paper is to investigate the solder joint performance of SMAFTI (smart chip connection with feedthrough interposer) under impact shear test and board level reliability test. Using the prototype samples of SMAFTI packages, impact shear tests are performed, which show Sn-Ag-Cu solder joints on Ni/Cu/Au surface are superior to those on Ni/Au. Thermal cycle test, bending cyclic test and drop test are conducted to evaluate the fatigue life of this package. The 0.1% Weibull life of thermal cycle is 989 cycles, and the life cycles of more than 20,000 and 10 cycles are obtained for cyclic bending and drop tests, respectively.