Effects of Cu/SnAgCu Powder Fraction and Sintering Time on Microstructure and Mechanical Properties of Transient Liquid Phase Sintered Joints

The effects of the sintering duration and powder fraction (Ag-coated Cu/SnAgCu) on the microstructure and reliability of transient liquid phase sintered (TLPS) joints are investigated. The results show that two main intermetallic compounds (IMCs, Cu₆Sn₅ and Cu₃Sn) formed in the joints. The Cu₆Sn₅ ratio generally decreased with increasing sintering time, Cu powder fraction, and thermal treatment. The void ratio of the high-Cu-fraction joints decreased and increased with increasing sintering and thermal stressing durations, respectively, whereas the low-Cu-fraction counterparts were stable. We also found that the shear strength increased with increasing thermal treatment time, which resulted from the transformation of Cu₆Sn₅ and Cu₃Sn. Such findings could provide valuable information for optimizing the TLPS process and assuring the high reliability of electronic devices.