Passive Immersion Cooling Modules

The challenges posed by high chip heat fluxes and ever-more stringent performance and reliability constraints make thermal management a key enabling technology in the development of electronic systems. The cooling of microelectronic components by immersion in dielectric liquids provides a most attractive alternative to more conventional electronic thermal management approaches, but regrettably the industry trend away from large mainframe computers and supercomputers has blunted the expansion of direct liquid cooling. Workstation, personal computer, and telecommunication equipment developers, who have historically relied on air cooling, have been reluctant to embrace liquid immersion due to concerns about the complexity and reliability of pumped liquid systems. Passive immersion cooling modules (PIMs), internally-filled with a dielectric fluid while externally cooled by air, provide a simple, highly reliable, and most effective thermal management alternative. Inclusion of fins on a PIM's "submerged condenser" can substantially expand the thermal performance envelope of the module. This chapter explores PIM system performance.