Effects of Temperature and Current Density on (Au,Pd,Ni)Sn_4 Redistribution and Ni-P Consumption in Ni/Sn3.0Ag0.5Cu/ENEPIG Flip Chip Solder Joints

摘要

The Ni/Sn-3.0Ag-0.5Cu/ENEPIG solder joints were used to investigate the effects of temperature and current density on (Au,Pd,Ni)Sn_4 redeposition and Ni-P consumption during electromigration (EM). In as-soldered state, (Cu,Ni)_6Sn_5 type IMCs formed at both the Sn3.0Ag0.5Cu/Ni and Sn3.0Ag0.5Cu/Ni-P interfaces. Temperature and current density played an important role in (Au,Pd,Ni)Sn_4 redeposition and Ni-P consumption. When the solder joints were applied with lower current density (0.9×10~3 A/cm~2) at lower temperature (85 °C), no obvious Ni-P consumption observed. (Au,Ni,Pd)Sn_4 particles still formed in the solder even after EM for 200 h, no (Au,Ni,Pd)Sn_4 particle was observed at both cathode and anode interfaces. When the solder joints were applied with higher current density (1.0×10~4 A/cm~2) at higher temperatures (150 and 180 °C), the (Au,Ni,Pd)Sn_4 phases preferred to redeposition only at the anode interface while no (Au,Ni,Pd)Sn_4 was detected at the cathode interface; Ni-P consumption was significantly affected by current direction, i.e., when the Ni-P layer was the cathode side, the consumption of Ni-P was significantly enhanced; when the Ni-P layer was the anode side, no obvious Ni-P consumption was observed.