Thermo-Mechanical Analysis of SiC Schottky-Barrier Diode Press-Pack Packaging using Finite Element Simulation

In this paper, a simple method for the analysis of the thermal and mechanical distributions inside press-pack 3300V/360A SiC SBDs have been presented. A 3D FEM based mechanical model was developed to analyze the static clamping force, junction temperature and conduction current distributions among the chips. The results of the thermal simulations show a low difference in temperature between the chips in the center of the device and those in the edges. Moreover, the temperature distribution inside each chip is not uniform, with slight difference, which could be attributed to the uneven surface pressure and current flow distribution inside each chip. The mechanical simulations showed that the clamping pressure was quite uniform in the contact layer of each chip during the non-working state. Meanwhile, it's been observed that the clamping pressure increased spontaneously among the chip surface. The pressure increase can be explained by the vertical thermal expansion, caused by different temperature dependent CTE of SiC and molybdenum among the contact layer.