Thermomechanical Reliability of Low-Temperature Sintered Silver Die Attached SiC Power Device Assembly

A thermomechanical reliability study was conducted on a low-temperature sintered silver die attached SiC power device assembly. The silver die attachment was formed by sintering nanoscale silver paste in air at 300 degC to form a strong bond between silver- or gold-coated direct-bond-copper substrates and silver-metallized SiC Schottky diodes. Using the 50% drop in the die-shear strength as the failure criterion, an accelerated thermal cycling experiment between 50 degC and 250 degC showed that the silver die attachment can survive more than 4000 cycles, indicating its high thermomechanical reliability at the interested temperature range. Established mainly by scanning electron microscopy/energy-dispersive spectroscopy, the drop of the die-shear strength during the thermal cycling was attributed to the pile-up of creeping dislocations to form microcavities at the grain boundaries of the sintered silver