Performance comparison of two-phase immersion cooling vs single-phase liquid cooling for high power density bare die packages

As chip power densities continue to rise with increasingly demanding AI applications, thermal pathfinding efforts are necessary to determine the relative benefits of single-phase water cooling compared to two-phase dielectric based immersion cooling. A significant constraint for 2PIC is the critical heat flux, an inherent limitation in two-phase boiling systems, which impacts the maximum supportable chip power. This study examines the core limitations of two-phase immersion cooling (2PIC) for high-power-density chips. We conducted experiments using a representative high-power chip with NovecTM 649 and OpteonTM SF33 as working fluids. The experiments were conducted over a range of thermal design power (TDP) levels and heat fluxes to pinpoint the maximum heat flux constraints of 2PIC. Different boiling enhancement coatings and both solid copper and vapor chamber boiler plates were tested. The performance of 2PIC was then benchmarked against a single-phase liquid cold plate utilizing deionized water. We analyzed the chip case to ambient thermal resistance and absolute case temperatures for both cooling methods, concluding with a discussion of their respective advantages and disadvantages.