Direct-on-chip two-phase jet impingement cooling of multichip packages: Distributed inlet-outlet nozzles

Abstract

This study introduces a package-level, direct-on-chip two-phase jet impingement cooling system utilizing R1233zd(E) refrigerant for a multi-chip server. The experimental arrangement includes a heater setup, replicating the NVIDIA P100 chip. The manifold houses distributed inlet-outlet nozzles arrays which sequentially cools the four low-powered High Bandwidth Memories (HBMs) followed by high-powered logic chip. The heat transfer and hydraulic pressure characteristics of both the logic chip and HBMs are systematically examined. (1) In logic-only case, the boiling curves at different flow rates converge into a single curve within the two-phase regime. The critical heat flux (CHF) reaches a maximum of 66.4 W/cm² at a flow rate of 2.5 L/min. (2) In HBMs-only case, boiling curves across individual HBMs similarly show a single distinct curve in the two-phase regime. CHF in HBMs was only observed at the lowest flow rate, with the maximum flux dissipated being 45 W/cm². (3) In simultaneous power dissipation in all chips, HBM power had no observable effect on logic chip CHF. At maximum HBM power dissipation, the logic chip’s CHF remained nearly constant at 66.4 W/cm². In total, the system dissipated 612.8 W (452.8 W in the logic chip and 40 W in each HBM). The heat flux had no noticeable impact on the cooler’s pressure drop, which peaked at 29.1 kPa (at 2.5 L/min). This work provides foundational insights into heat transfer and pressure dynamics in multi-chip modules within a confined package environment. The findings offer valuable guidance for implementing effective two-phase jet cooling in multi-chip systems.