Comparison of Mounting Methods for Directly Attached SiC Power MOSFET Bare Dies on a PCB

Abstract:
If flexibility in the number of semiconductors or their precise, space-saving positioning is required in the design of fast-switching converters, the direct application of bare dies to printed circuit boards (PCBs) can be an effective and reliable method. This is particularly the case when, as in pulsed applications, cooling of the MOSFETs plays a minor role. The present work discusses three methods for mounting 1200 V SiC power MOSFETs directly on a PCB: solder paste, solder foil and silver conductive adhesive. Each method is tested on a standard PCB and evaluated in terms of switch-on resistance Rds(on), transient thermal impedance Zth, switching behavior, costs and the presence of voids using computer tomography (CT).