Thermal conductivity of Cu-Sn transient liquid phase sintered interconnects for high power density modules

Abstract

Transient Liquid Phase Sintering (TLPS) is a novel high power density module and high temperature electronics interconnect technology. The copper-tin (Cu-Sn) TLPS system is of particular interest because of its fast process completion, high melting temperature, and low cost. The high thermal conductivity of Cu and Cu-Sn Intermetallic Compounds (IMCs) compared to other metals and IMCs should make it an ideal interconnect for high power density modules. The thermal conductivity of paste-based TLPS joints has not been studied experimentally. In this paper, the thermal conductivity of joints formed from Cu-Sn sinter pastes between power diodes and Direct Bond Copper (DBC) substrates is characterized. The transient thermal response of the power module structure was recorded with the T3Ster test platform. The resulting thermal structure functions are used in conjunction with FloTHERM simulations to determine the thermal conductivity of the interconnects. The Cu-Sn TLPS joints had an average thermal conductivity of 140.2 W/mK. These results are in good agreement with simulation predictions from prior work. The high thermal conductivity and high melting temperature demonstrate that Cu-Sn TLPS joints are a promising interconnect technology for high power density module.