Enhanced Mechanical and Thermal Properties of Ag Joints Sintered by Spark Plasma Sintering

Nano-silver paste has been considered to be one of the most promising materials for interconnects of semiconductor devices operating at high temperature. However, its application is limited by conventional sintering methods due to the long dwell time. In this paper, a spark plasma sintering (SPS) technique with a very short sintering time of no more than 5 min was explored for the sintering of nano-silver paste. The effects of sintering conditions including pretreatment time, sintering temperature, dwell time and applied pressure on shear strength and thermal conductivity of the sintered Ag joints were investigated. The shear strength of sintered Ag joints increased as the sintering temperature and applied pressure increased. Robust sintered Ag joints with an average shear strength of 40.18 MPa were obtained by sintering at 300 degrees C for 5 min under a pressure of 3 MPa. The thermal properties were improved by pretreating the nano-silver paste for a shorter time. Thermal conductivity of 41.50 W m(-1) K-1 is obtained for samples pretreated for 25 min and sintered at 250 degrees C for 5 min.