Reliability evaluation on Ag sintering die attach for SiC power modules during long-term thermal aging/cycling

This study was carried out to systematically evaluate the reliability of Ag sinter joining in wide bandgap (WBG) power modules. SiC die-attached module by pressure¬less Ag joining was subjected to long-term high-temperature aging (250°C) as well as harsh thermal/cooling shock test (-50/250°C). Each measurement resulted in different degradation tendency of mechanical behaviors. The thermal aging process led to a modest declining rate from initial 43.92 MPa to 31.58MPa after 500h. While the bonding reliability was much more vulnerable to thermal shock cycles by firstly increased and then decreased to 29.38 MPa after 500 cycles. The mechanism for each kind of bonding strength deterioration was then investigated by comprehensive microstructure evolution.