T/R Module Board Cooled With Thin-Film Evaporators

We propose to develop a superior thermal management system for high-power radar T/R modules at the Lower Replaceable Unit or LRU board level. We will incorporate evaporators into a new LRU board such that an evaporator is adjacent to each T/R module. Ourunique and proprietary thin-film evaporators remove large amounts of heat via ultra thin-film evaporation of a working fluid. After evaporation, the fluid's vapors are channeled to the edge of the board, where the vapor is cooled and condensed back to aliquid and returned to an evaporator. The temperature drop across our LRU board should be about 10¿C, as opposed to the approximately 40¿C temperature drops across standard T/R module boards. The lower thermal resistance of our T/R module board willreduce the operating temperatures of future higher-power MMIC's, which will increase the reliability of the radar system.Our proposed design has many advantages. The cooling mechanism is ideal for the limited space available inside a T/R module board. The thin-film evaporators will be able to remove heat at rates of up to 200 W/cm2, which is comparable to spray coolingmethods but with lower power and space requirements and fewer ancillary components. Our thin-film evaporators incorporated into a T/R module board will reduce the thermal gradient across these boards and allow the operation of the radar system at highpower densities and frequencies. Similar in-board active cooling systems could be designed for other high-heat flux electronic devices, such as solid-state lasers, electronic power modules, computer network servers, and computer workstations with multipleprocessors. ATEC is currently working on developing a potentially high volume electronic cooling product utilizing our thin-film evaporator technology.