Investigation of reliability issues in sintered silver interconnected power devices and its lifetime prediction by FEM and experiment

Inhalt:
Lifetime and reliability of power semiconductors with standard die attach solder technology can be improved by silver sintering technology. Sintered silver interconnect technology is dominating for high temperature applications because of its improved thermal and mechanical properties than the conventional solder interconnect. Thermal fatigue in sintered silver causes material degradation, which leads to major reliability issues such as die attach failure in power modules. The sintering technology is highly dependent on time and temperature, which dominates plastic deformation in the sintered silver material. Moreover, creep at higher temperature is an influencing parameter for reliability issues in the sintered power module. Porosities during sintering process changes the mechanical properties of the sintered layer that makes some reliability challenges in the system. Failure modes such as wire bond lift-off, heel cracking and crack in the metallization layer are observed. Silver sintered power stacks require different failure mode analysis to predict the lifetime of the whole assembly. The influence of plastic and creep deformation dependent on porosities should be considered during the development of lifetime model. This paper gives an overview on different failure modes on sintered silver interconnected assemblies of various substrates with different die thickness and sizes. Reliability study and lifetime model for the silver sintered assemblies are investigated by various experiments and numerical simulation such as passive temperature cycle test and active power cycle test which will be addressed in this paper.