Enhancing thermal-mechanical performance of micron Ag/ZrW2O8 nanorod die-attach paste with low thermal expansion

Abstract

Negative thermal expansion not only challenges the traditional lattice concept, but also provides new opportunities for regulating the thermal expansion coefficient and addressing the increasing reliability demands in power device packaging. In this study, ZrW2O8 nanorods were firstly introduced into the micron Ag paste via a facile low-temperature (≤300 ℃) low-pressure (<10 MPa) sintering. The pinning and negative thermal expansion mechanisms contributed by the homogeneously dispersed ZrW2O8 nanorods significantly mitigate the thermal expansion mismatch and suppress the microstructure deterioration in SiC power module, which was also verified by finite element (FE) simulation. The Ag@2%ZrW2O8 (2% of the total weight of Ag) specimen possessed outstanding long-term reliability with a die-shear strength of 29.63 MPa after 1000 thermal shock cycles from −50–250 ℃. The novel findings can be inspiring on interconnected material optimization and selection in electric packaging application as well as reliability evaluation in the service condition.