Comprehensive Study on the Characteristics of Large Area Transient liquid phase sintering (TLPS) Joint for SiC module

Abstract:
This study employs the Transient Liquid Phase Sintering (TLPS) process to achieve the connection between the substrate and the heat sink in power modules, studied the impact of printing thickness on the strength and reliability of the connection layer, and comprehensively revealed the differences in packaging performance between TLPS and traditional solder from the aspects of mechanical properties, thermal resistance, connection layer reliability, and module service life. The results show that the TLPS connection layer prepared in this paper is composed of Cu3Sn, Cu6Sn5, Cu, and Ag3Sn, and contains 15% porosity and a small amount of residual carbon. After matching the printing thickness with the warpage of the substrate, the connection layer has no obvious delamination defects, the strength reaches 60MPa and is uniform distributed, which is 30% increase compared to soldering. Under the thermal shock conditions of -65-150deg C, the reliability of the TLPS joint is significantly better than that of the SnSb5 solder layer. Compared with soldering, the total thermal resistance of the power module using the TLPS process is reduced by 7%, indicating that TLPS can effectively enhance the module's heat dissipation and outflow capabilities. After undergoing 18,000 long cycle power cycle tests, the silver sinter-ing layer on the back of the chip degrades due to the accumulation of plastic strain, and the total thermal resistance of the TLPS and soldered modules increased by 60% and 48.6% respectively, with the module service life being 6000-7000 cycles. The large-area TLPS process causes greater fluctuations in the chip's junction temperature, which has a negative impact on the service life of the module, but provides a low-cost technical solution for enhancing the heat dissipation and outflow capabilities of high power module packaging.