Design Considerations, Demonstration, and Benchmarking of Silicon Microcold Plate and Monolithic Microfluidic Cooling for 2.5D ICs

In this paper, we evaluate the use of silicon microfluidic cooling in conjunction with 3D printing techniques to create an ultra-low profile cooling system tailored for 2.5D packages. We present the thermal challenges in 2.5D devices including higher aggregate package power and thermal coupling, and use finite volume and finite difference modeling to demonstrate both thermal and electrical benefits of implementing a microfluidic cooling solution. A field-programmable gate array (FPGA) package with five discrete dice is used as the test vehicle for experimental demonstration. Two discrete implementations of the microfluidic heat-sink are demonstrated: an attached silicon cooler where micropin-fin heat-sink is etched on a separate piece of silicon, and a monolithic cooler with the micropin-fins etched directly into the backside of the dice. Both are capped with low-profile 3D printed fluid delivery manifolds. We demonstrate very low junction-to-inlet thermal resistance values of 0.094 °C/W with the attached microfluidic silicon cooler and 0.074° C/W with the monolithic heat sink for the FPGA core die.