Development of Accelerated Testing of Thermal Degradation in Metallized Ceramic Substrates for SiC Power Modules

Abstract:
In order to shorten the testing time of thermal cycling for metallized ceramic substrates, a new accelerated fatigue test was developed. In this approach, maximum tensile stress in the ceramics during thermal cycle from -40 to 250deg C was estimated by FEM analysis. The stress swing in the ceramic substrates during the thermal cycling was roughly simulated by four-point bending the metallized test piece repeatedly at a frequency of 1 Hz at 250deg C. When the maximum tensile stress caused by the bending was two times larger than that created by the cooling to -40deg C, the time to failure by the repeated external loading for the conventional Si3N4 substrates was less than 1/60 of the time to delamination of the copper plate by the thermal cycling.