Comparative study of how buffering spacer materials affect the reliability of double-sided cooling SiC power module by finite element modeling

With increasing power density of electronic devices, the heat dissipation is becoming a non-negligible issue. Thermal management is critical for improving the electric properties and reliability of power module. Compared to the traditional single-sided cooling structure, double-sided cooling module has multiple cooling paths and lower parasitic inductance, which effectively promotes the thermal reliability of power module. In this article, a double-sided cooling SiC power module with low parasitic parameter of 2.4 nH was designed and the differences in the thermal performance and von mises stress of power modules by different buffering materials were investigated. The power module using copper buffering has the lowest junction temperature (Tj) of 110°C as copper possesses the highest conductivity among the three different bufferings. However, the Mo₇₀Cu₃₀ and Cu-Epoxy array buffering modules have a lower thermal stress even with higher Tj (~5%). Meanwhile, the highest thermal stresses in different bonding layers of Cu-Epoxy array buffering module are all nearly one half of the Cu buffering module’s stress. This is because the epoxy resin is able to absorb and relieve the thermal stress resulted from the mismatch coefficient of thermal expansion (CTE) of packaging materials.