SymCool™ B-TRAN™ Power Module Design Considerations and Characterization

B-TRAN™ devices produced in a commercial foundry demonstrated excellent results with low die to die variability, which lays a solid foundation for current sharing control in power modules. Design considerations, simulation, and characterization results of SymCool™ B-TRAN™ bidirectional power modules are reported in this paper. B-TRAN™ itself is strictly symmetrical and bidirectional in nature and has a positive temperature coefficient. The cascode MOSFETs provide additional current sharing compensation in case there is mismatch in driving current and device performance at various temperatures. Packaging impedance is as low as 0.4 mΩ and 10 nH at 35 KHz for a 1200V/160A rated power module, with a unique Kelvin Source designed to reduce gate-source loop inductance. Finally, SymCool™ bidirectional power module with 4mΩ resistance @ 160A was achieved due to B-TRAN™ die ultra-low Vceon and enabled by careful design of interconnections and module material selection. Direct-Plated-Copper (DPC) with an aluminum nitride (AlN) substrate package offers features such as double side cooling, compact dimensions, and moreover, an isolated package surface, which makes it convenient to parallel multiple power modules to achieve high power ratings. Die attachment by Ag sintering provides a better coefficient of thermal expansion (CTE) and better reliability than wire-bonding based counterparts.