Thermal management of power electronics using thermoelectric coolers

Abstract

Many high power electronic devices, such as power amplifies and multiprocessors, operate at high temperatures close to or at the edge of their reliability, which could severely impact performance and operating lifetime. These devices thus need cooling to improve performance and reliability. Conventional thermal management techniques, most of which are discussed, are not well suited to the specific problem of cooling discrete or localized heat dissipating devices since they generally cool the whole board. Moreover, these techniques have difficulty dealing with the large heat fluxes associated with the high density packaging of power devices. The specific problem of spot cooling of power devices can be very effectively solved by using the combination of diamond substrates and a thermoelectric cooler. The highest power components would be mounted directly on a diamond substrate (ideally the top substrate of the cooler) allowing the cooler/diamond combination to maintain the temperature of the device from a few degrees to tens of degrees below that of the substrate on which the cooler is mounted (diamond or any other high thermal conductivity material). This will allow the device to operate at a low enough temperature to increase both reliability and clockspeed. It has been determined that the highest cooling power densities will be achieved with thin film coolers with cooler leg lengths on the order of 20 to 50 microns. The results of a solid state power amplifier (MMIC) cooled using a diamond/cooler combination are presented and discussed.