Embedded Micro-Pin Fin Heat Sink of Two-Phase Liquid Cooling for High Heat Flux 3D ICs

This paper presents a novel two-phase liquid cooling solution of high-power integrated circuit (IC) chips using embedded micro-pin fin heat sink (MPFHS). A titanium thin film heater and two resistance temperature detectors (RTDs) are deposited on the active surface of a silicon chip, to simulate the functional dice and measure chip temperature, respectively. The backside surface of silicon chip is etched to form the embedded MPFHS, and then bonded to a silicon cap. Printed circuit board (PCB) is designed and fabricated to power the heater and collect signals from RTDs. The coolant (deionized water) is fed and collected through the thin side openings of the chip. Manifolds are 3D printed with stainless steel to properly match the openings. Experimental setup of two-phase liquid cooling loop is built for testing and characterization. A wide range of coolant flowrate and heat flux of heater is tested. Heat flux up to 188 W/cm(2) is achieved with small coolant flowrates experimentally. Chip temperature and temperature gradient linearly increase as heat flux increases, which can be reduced by increasing coolant flowrate. In two-phase regime, chip temperature and pressures at inlet and outlet are highly fluctuated, which is not preferable in chip cooling. Further investigations are to be carried out for a more stable cooling.