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In this paper, development of single-phase liquid cooling techniques for flip chip ball grid array packages (FBGAs) with high flux heat dissipations is reported. Two thermal test chips with different footprints, 12 mm 12 mm and 10 mm 10 mm, respectively, were used for high heat flux characterizations. A liquid-cooled aluminum heat sink with an area of 15 mm (L) 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. A variable speed pump was used to provide the pressure head for the liquid cooling loop. The measured thermal resistance results ranged from 0.44 to 0.32 C W for the 12-mm chip case and from 0.59 to 0.44 C W for the 10-mm chip case, both under flowrates ranging from 1.67 10 6 m 3 s to 1.67 10 5 m 3 s. An analytical model of the flow and heat transfer in microchannel heat sinks is also presented. Computational predictions agree with the measurements for pressure drop within 15% and thermal resistances within 6%. The analytical results indicate that thermal interface resistance becomes a key limitation to maximizing heat removal rate from electronic packages.

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