Flexible PCB-Based 3-D Integrated SiC Half-Bridge Power Module With Three-Sided Cooling Using Ultralow Inductive Hybrid Packaging Structure

Silicon carbide (SiC) devices are capable of high switching speeds and also enable high switching frequency in power electronic converters. However, this feature poses substantial challenges to packaging, especially limiting the loop inductance. The traditional wire-bonding packaged power module has large parasitic inductance, which will cause voltage overshoot, oscillation, parasitic turn-on, and EMI issues. In order to reduce the parasitic inductance, this paper proposes a flexible printed circuit board (FPCB) based full SiC half-bridge power module with a novel low inductive hybrid packaging structure and three-dimensional (3-D) integration method. This hybrid packaging structure has an ultrathin FPCB substrate stacked on a direct bonding copper (DBC) substrate, which forms a multilayer 3-D power loop. The SiC chips are soldered on the DBC substrate for good thermal dissipation through a cavity in the FPCB substrate. After power loop optimization, the power loop inductance of a 1200-V/120-A SiC power module is only 0.79 nH. The power module consists of three submodules, which are connected by the bendable FPCB substrate. The bendable power module enables maximum utilization of 3-D space. The gate drive, decoupling capacitors, and dc-link capacitors are also integrated and 3D-structured using rigid-flexible PCBs. Moreover, the cooling system is a high-efficiency three-sided cooling structure for the bendable power module. The simulation results show that the three-sided cooling structure reduces the heatsink volume by 50%. Applying this method, the converter can be designed as a system-in-package and a 3D-structured compact system. The power density of a 20-kW three-phase inverter will reach 19.3 kW/L based on this power module. In this paper, the 1200-V/120-A power module fabrication and assembly processes are given. Finally, the static and dynamic experimental comparisons are done for a commercial power module and the proposed power module. The experiment results show that the voltage overshoot of the proposed module reduces about 5.8 times and are consistent with the simulation results. Meanwhile, the proposed power module switching speed is 1.8 times faster than the commercial module under zero external gate resistors and the switching loss can reduce by about 60%.