Nathan P. Lower

Water-Based Microchannel and Galinstan-Based Minichannel Cooling Beyond 1 kW/cm

Microchannel heat sinks are a relevant thermal management technology because the combination of surface area enhancement and small length scales results in low wall-to-bulk temperature differences. Previously, a thermal resistance of 0.09°C/W was achieved when a heat flux of 790 W/cm2 was imposed on a 1 cm × 1 cm footprint portion of a 400-μm-thick Si substrate utilizing single-phase water-based microchannel cooling and a 214 kPa pressure difference to drive the flow. Galinstan, a gallium, indium, and tin eutectic, may be utilized for single-phase liquid metal cooling of microelectronics due to its subambient melting temperature and high thermal conductivity. This paper describes the fabrication and assembly of water-based microchannel and Galinstan-based minichannel heat sinks and the flow sheets utilized to characterize them under the aforementioned constraints. The prefix mini rather than micro is used to describe Galinstan-based heat sinks because optimal channel widths are hundreds as opposed to tens of micrometers. The aforementioned thermal resistance of 0.09 °C was experimentally reproduced. Unprecedentedly low thermal resistance and high heat flux in single-phase water-based microchannel cooling, i.e., 0.071°C/W and 1003 W/cm2, respectively, were achieved. The first experimental data on Galinstan-based minichannel heat sinks are also reported. A thermal resistance as low as 0.077°C/W was achieved at a heat flux of 1214 W/cm2 and a maximum heat flux of 1504 W/cm2 was reached.

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Microchannel heat sinks are a relevant thermal management technology because the combination of surface area enhancement and small length scales results in low thermal resistance. Previously, a thermal resistance of 0.09°C/W was achieved when a heat flux of 790 W/cm2 was imposed on a 1 cm × 1 cm footprint portion of a 400 μm-thick Si test specimen utilizing single-phase microchannel cooling. Water was driven through the assembly with a 214 kPa pressure difference [1]. Under the same constraints, we report experimental results in which a heat flux of 1002 W/cm2 and thermal resistance of 0.071°C/W have been achieved when water was the coolant. Preliminary results with a liquid metal minichannel heat sink are also reported and suggest that thermal resistances as low as 0.45°C/W may be achieved under the same constraints.