Thermal Performance of Transient Liquid Phase Diffusion Bonded Multi-Layer Cold Plate

The performance of CPU/GPU are updated year by year, and in recent years the heat generation of these chips have increased significantly. For High Performance Computing (HPC) cooling or High-end server cooling, single phase Direct Liquid Cooling (DLC) is becoming primary cooling solutions. The latest thermal design power (TDP) of CPU/GPU has reached > 600W level, and high-performance cold plate is a key factor for next generation cooling solutions. Traditional parallel fin type microchannel cold plates have been adopted, and to enhance their thermal performance, narrower fin pitch cold plates have been developed. However thinner fin thickness results in lower fin efficiency, and high pressure drop. In this paper, an innovative cold plate design is presented with evaluated thermal performance, pressure drop, and manufacturing cost. The Multi-Layer Cold Plate (MLCP) consists of multiple etched sheets laminated by Transient Liquid Phase (TLP) diffusion bonding. In thermal performance comparison between MLCP and parallel fin cold plate, the MLCP showed 20% improvement in thermal performance at similar pressure drop. TLP diffusion bonding enables MLCP to be manufactured continuously with high capacity and reasonable cost. The cost depends on etching sheet size. For a sheet size of 65mm x 45mm it is confirmed that MLCP can be manufactured at the same cost as parallel fin.