As SiC power modules are increasingly applied in high-voltage systems, higher requirements are imposed on their operational stability under such conditions. This paper proposes a monolithic multilayer ceramic substrate to reduce the electric field strength at the triple point in SiC power modules. Traditional multilayer DBC substrates are typically fabricated by soldering two separate DBC substrates together. These soldered interfaces are often mechanically unreliable, and electrical continuity between the upper and intermediate copper layers is not ensured. In contrast, the structure proposed in this work adopts a monolithic substrate in which a single 300 μm thick copper layer is embedded without the use of additional solder. By eliminating solder interfaces, the proposed configuration improves thermal conduction and enhances overall heat dissipation. Compared with a conventional single-layer DBC substrate, the proposed multilayer structure incorporates an additional intermediate copper layer that is connected to the midpoint of the DC-link capacitors. Simulation results show that the proposed structure reduces the electric field strength at the module triple point to 44% of that in the conventional design. Furthermore, the designed 800 V SiC power module achieves a parasitic loop inductance of approximately 3.9 nH at 10 MHz with improved thermal performance.
Zhang et al. (Mon,) studied this question.