Enhancement of nano-silver chip attachment by using transient liquid phase reaction with indium

Highlights: • A simple method of introducing In resolves critical problems of sintered Ag joint. • With In addition, the porosity decreases substantially from 24 vol% to 5 vol%. • With In addition, the interfacial wettability with Ag was greatly improved. • With In addition, shear strength increased above 40 MPa after 300 °C aging for 100 h. • Sintered AgIn joint exhibit excellent high temperature reliability at 300 °C. Nano-silver paste is considered one of the most promising interconnection materials for high-power and high-temperature applications owing to its excellent electrical and thermal properties and low bonding temperature. However, sintered silver joints have several critical issues, including high porosity, poor wettability, and poor high-temperature reliability in air. In this study, we report that these problems can be resolved by introducing indium into the sintered silver joints. To support these claims, the microstructures and die shear strengths after bonding and high-temperature aging at 300 °C in air of both sintered nano-silver joints and sintered silver-indium joints are reported. The fracture surfaces after die shear tests are also analyzed. With the addition of indium, the porosity of the sintered joint decreases substantially, and the wettability improves considerably. Most importantly, the oxidation at high temperature is no longer an issue. The die shear strengths remain higher than 40 MPa even after aging at 300 °C in air for 1000 h.