In situ bridging effect of Ag2O on pressureless and low-temperature sintering of micron-scale silver paste

Silver sintering joining technology provides lead-free die attachment with excellent thermal conductivity and compatibility with high-temperature (>= 300 degrees C) applications. However, sintering affordable micron-scale silver particles requires high temperature and the assistance of high pressures, which can damage chips and increase the manufacturing cost. In this article, we achieved the low-temperature, pressureless sintering of micron-scale silver particles by employing an active Ag2O additive as a bridge among the micron-scale silver particles. The Ag2O was reduced in situ to nanoscale silver to activate the surface of the micron-scale silver particles, resulting in the rapid diffusion and densification of silver particles at low temperature. An optimized composition of Ag-10% Ag2O exhibited a bonding strength of over 40 MPa at only 180 degrees C without any additional pressure. The results suggest that affordable micronscale metal particles can be sintered using a suitable activating additive under an energy-efficient and eco-friendly fabrication process. (C) 2016 Elsevier B.V. All rights reserved.