Accelerated thermal fatigue test of metallized ceramic substrates for SiC power modules by repeated four-point bending

Maximum tensile stress in the ceramics during thermal cycle test (from −40 to 250°C) of active metal brazing (AMB) substrate was estimated by the finite element method (FEM) analysis, because such a tensile stress is the driving force of Cu plate delamination from the ceramic plate. In order to accelerate thermal fatigue of the AMB substrate, tensile stress 1.5–2.1 times larger than the maximum thermal stress at −40°C was applied to ceramic plate by four-point bending the AMB substrate at 250°C repeatedly at a frequency of 1 Hz. The time to failure by repeated bending of the SÌ3N4-AMB substrate was less than 1/40 of the time to delamination of the Cu plate by the thermal cycling.