Single-phase liquid cooled microchannel heat sink for electronic packages

The study of a single-phase liquid cooled microchannel heat sink for electronic packages is reported. Two flip chip ball grid array packages (FCBGA) with different chip footprints, 12 mm x 12 mm and 10 mm x 10 mm, were used for high heat flux characterizations. A liquid-cooled aluminum heat sink with finned base dimensions of 15 mm (L) x 12.2 mm (W) populated by microchannels was designed and fabricated. The microchannel heat sink was assembled onto the chip, using a thermal interface material to reduce the contact thermal resistance at the interface. The measured junction to inlet fluid thermal resistances ranged from 0.44 to 0.32 deg. C/W for the 12 mm chip under the test flowrate range. The higher thermal resistance range from 0.59 to 0.44 deg. C/W was obtained for the 10 mm chip due to the higher heat spreading resistance at the heat sink base. An analytical method that takes into account the simultaneous developing flow in microchannel heat sinks is developed to predict the pressure drop and thermal resistance. The calculations agree well with the measured pressure drop and thermal resistances. The respective thermal resistance elements are also analyzed and presented