Synthesized experiments and analysis of microchannel heat sinks in electronics packaging

In this paper, the synthesized experiments and analysis of microchannel heat sinks (MCHSs) in electronic packaging are presented. Microchannel heat sinks together with the flip chip ball grid an-ay (FCBGA) packages were characterized with water and FC-72 as the coolants. Experiments were conducted by reducing the flow rate at a fixed power input in both normal setup with upward heating and inverted setup with downward heating. Water cooling data were obtained in single phase, whereas deviations from the single phase regime were observed for FC-72 cooling. Especially, thermal performance degradation was identified for the FC-72 cooled MCHS in the inverted setup, which could be attributed to the flow stratification in microchannels and should be avoided in practice. Computations that incorporate MCHSs and electronic packages are also carried out to study the heat transport across the package. The package thermal path is obtained and on-chip hot spot effect is examined in association with the MCHSs. The heat sink level thermal enhancement can be considered to minimize the hot spot effect at small thermal interface resistance.