Thin Thermally Efficient ICECool Defense Semiconductor Power Amplifiers

Traditional power electronics for military and fast computing applications are bulky and heavy. The “mechanical design” of electronic structure and “materials” of construction of the components have limitations in performance under very high temperature conditions. The major concern here is “thermal management.” To be more specific, this refers to removal of high-concentration hotspot heat flux >5 kW/cm2, background heat flux >1 kW/cm2, and “miniaturization” of device within a substrate thickness of <100 μm. We report on the novel applications of contact-based thermoelectric cooling (TEC) to successful implementations of high-conductivity materials - diamond substrate grown on gallium nitride (GaN)/AlGaN transistors to keep the hotspot temperature rise of device below 5 K. The requirement for smarter and faster functionality along with a compact design is considered here. These efforts have focused on the removal of higher levels of heat flux, heat transfer across interface of junction and substrate, advanced packaging and manufacturing concepts, and integration of TEC of GaN devices to nanoscale. The “structural reliability” is a concern and we have reported the same in terms of mean time to failure (cycles) of SAC305 (96.5% tin, 3% silver, 0.5% cu) solder joint by application of Engelmaier's failure model and evaluation of stresses in the structure. The mathematical equation of failure model incorporates the failure phenomena of fatigue and creep in addition to the dwell time, average solder temperature, and plastic strain accumulation. The approach to this problem is a nonlinear finite element analysis technique, which incorporates thermal, mechanical, and thermoelectric boundary conditions.