Novel high performance thermoelectric microcoolers with diamond substrates

The concepts discussed in previous papers have been implemented in novel miniature thermoelectric coolers (TECs) with diamond substrates. Micromodules with TE legs 0.2 mm long and 0.4×0.4 mm² in cross-section were developed. A maximum temperature difference of 67 K was obtained, a value comparable to the ones obtained for commercial TECs with TE leg length of 1 mm and higher. Heat flux densities of 70 W/cm² at cold junctions were achieved. Taking into consideration the hot side thermal resistance, the minimum TE leg length was calculated. It was found that using high thermal conductivity substrates allows miniaturization of the TE legs near its lower theoretical limit defined by electrical contact resistance only. Cold side heat flux densities in excess of 100 W/cm² can be attained in such coolers. This makes them ideal to solve thermal problems of high density localized heat sources such as power amplifiers, microprocessors and other power electronic devices which are already operating at the edge of their reliability