Exploring Novel Second Level Cooling Methods for Low Profile IPMs

A major draw of low profile surface mount Intelligent Power Modules (IPM) is their suitability for use in space-constrained motor drives. Traditional cooling methods such as Aluminum heat sinks tend to be bulky and hence incompatible with this new class of compact motor drive modules. For the first time, this paper explores the use of Pyrolytic Graphite Sheet (PGS) - a 70 micrometer thin flexible material that has 2x better thermal conductivity than copper Cu - for use in top-side cooling of low profile Intelligent Power Modules (IPM). Additionally the combination of PGS and Semi-Sealing Material (SSM) is also explored. Simulation and experimental studies performed on 0.9mm thick CIPOS(TM) Nano modules from Infineon Technologies using PGS and PGS+SSM as heat spreader and heat pipe show 35 % and 42 % improvement respectively in power output capability of these modules without increasing the bulk of the motor drive board.