Thermal-hydraulic performance of microchamber heat sinks with run-through metal pillar arrays and hot-spot oriented manifold inlets

Microchannel heat sinks have great potential in cooling miniaturized electronics with high heat flux. However, manufacturing difficulties and pressure drop penalty are concerns need to be considered. In this work, pizza-box shaped microchambers were embedded in LTCC substrates to cool high power SiP modules. Each microchamber heat sink has a manifold inlet located just below the hot spot to generate vertical impingement jet for direct cooling of the hot spot. By adopting the form of microchamber instead of microchannels, the pressure drop was reduced. A flow rate of 10ml/min driven by a pressure below 1 kPa was sufficient to reduce the maximum temperature from 180 degrees C to 50 degrees C. Run-through Ag pillar arrays were also used to enhance both conductive and convective heat transfer. The substrate thermal resistance was decreased by two orders of magnitude to about 0.2 K/W. The Nusselt number was increased by 60% similar to 110%. An index with obvious physical significance, ease measurement, and small uncertainty has been defined to evaluate the cooling efficiency. The cooling efficiency of the microchamber heat sinks could reach 95% under normal temperature environment. Fast and effective cooling has been achieved and high system reliability was also guaranteed.