DIRECT IMMERSION COOLED MICROELECTRONICS HEAT SINKS: EFFECTS OF TEST FLUID AND BONDING TECHNIQUE

There has been a great deal of interest in recent years relating to the use of direct liquid immersion cooling for heat dissipation from microelectronic components. The high levels of circuit integration place size constraints on any techniques used for heat removal. This paper presents results obtained using a novel heat sink which addresses the need for a mechanism to remove high heat fluxes, while at the same time dealing with space limitations. This heat sink consists of cavity structures etched into a silicon surface, utilizing manufacturing processes similar to those used in the production of the chips themselves. The enhanced surface features are in the form of pyramidal cavities with a mouth size as low as 12 μm, and cavity density as high as 420 cavities/cm2. Tests were conducted using thin film heaters deposited on a silicon surface as the heat source. Data obtained from a bonded heat source–heat sink combination indicated very low values of overshoot at boiling incipience. The cooling characteristics of these etched silicon heat sinks were studied in two dielectric fluids; R-113 and FC-72. The boiling performance of an epoxy bonded heat sink was compared with that of a direct bonded heat sink.