Application of high-fluence convective cooling to pulsed power components

Cooling of high-energy high-power components by immersion in water or by circulating water within them is common. A major advance in cooling of VLSI substrates by water under laminar flow within microchannels has started to be integrated into a number of practical subsystems. By increasing the fluid velocity in a microchannel the convective heat transfer coefficient increases significantly when fluid flow changes from laminar to fully developed turbulence. While the higher convective heat transfer coefficient, which implies greater heat transfer and higher performance for the device being cooled, the means and mechanical design to achieve fully developed turbulence differ from the laminar systems. The major differences include fluid pressure, pressure drop per unit length, channel aspect ratio, heat-sink material properties, and thermal expansion compatibility to substrates. These differences are discussed in the context of a design example for a 1,180 W/cm/sup 2/ microchannel heat sink applied to an IGBT module.