Microstructures and properties of Ag–Cu–Ti–In composite fillers for electronic packaging applications

With excellent thermal cycling performance, active metal brazing (AMB) ceramic substrates have been highly competitive materials for high power packaging. In related researches, composite filler is an effective way to improve the comprehensive performance of ceramic substrates. The effects of particle hardness on microstructure and properties (i.e., coefficient of thermal expansion (CTE), elastic modulus and compression properties) of Ag–Cu–Ti–In composite fillers were studied in this paper. The results showed that the microstructures of composite fillers were refined with the increase of graphite and TiC content. Meanwhile, the reduction of CTE of composite fillers added with TiC particles is better than that of graphite particles. The CTE of G10 sample is 7.4% lower than that of the sample without particle, and T10 sample is 8.9% lower. Furthermore, TiC particles increased both elastic modulus and yield strength of the composite fillers while graphite particles mainly had an opposite effect. The bulk modulus of the composite fillers drops sharply from 95.96 to 12.64 GPa when the content of graphite particles was 10 wt% compared with that of the filler metal without particles. The yield strength of composite filler with graphite content of 1 wt% reaches 380 MPa, which is caused by the in situ reaction between graphite and Ti. However, the elastic modulus and the yield strength of the composite fillers increases with the increase of TiC content.