Advanced spreaders for enhanced cooling of high power chips

Abstract

Advanced spreaders for cooling a 10 × 10 mm underlying computer chip with a central hot spot (CHS) could remove > 85 W of dissipated thermal power at junctions' temperature < 100°C. The spreaders comprise a 1.6 - 3.2 mm thick Cu substrate and an 80-μm thick micro-porous copper (MPC) surface cooled by saturation nucleate boiling of PF-5060 dielectric liquid. Investigated are the effects of varying the heat flux at the chip's 1 and 4 mm2 CHS and the impedance of thermal interface material (TIM) between the Cu substrate and underlying chip. Results confirmed the effectiveness of the MPC spreaders for cooling the chip and mitigating the effect of CHSs. With a TIM impedance of 0.19°C-cm2/W, the MPC spreader with a 3.2 mm-thick Cu substrate removes 90.1 W and 87.85 W for the chip with 1 and 4 mm2 CHS when the heat flux ratio (HFR) at CHSs = 6. The chip maximum surface temperatures at the CHSs are 90.16°C and 96.6°C and the spreader's footprint areas are 25.5 and 25.25 cm2, respectively. Decreasing the TIM impedance to 0.02°C-cm2/W decreases the chip's maximum surface temperatures to 73.4 and 76.1°C, but slightly changes the removed thermal powers from the MPC surface to 90.3 W and 86.24W, respectively.