A Numerical Study of Single Phase Dielectric Fluid Immersion Cooling of Multichip Modules

摘要

Immersion, single phase free convection cooling of multichip modules on a printed circuit board in a pool ofdielectric fluid was examined numerically, with experimental verification of baseline cases. A multi-chip modulewith multiple thermal test cells with temperature sensing capability was simulated. The commercially availablecomputational fluid dynamics program from ANSYS, Fluent, was used with the electronics packaging front end,Icepak, employed to create the models and compact conduction modules. Simulations were first performed of anexperimental test vehicle which had five 18 mm by 18 mm die, arranged in a cross pattern, equally spaced die, 25mm between them. Two of the die were aligned vertically with the center die, two aligned horizontally with it. Theboard was suspended vertically in a large pool of dielectric fluid. Heat was dissipated in the die at a flux of up to 2W/cm~2, based on the die surface area. Simulation results were compared with experimentally measured dietemperature values and excellent agreement was seen for the cases of one die heated and all five die uniformlyheated with the board cooled by FC-72. A numerical parametric study was performed to examine the effect of diesize and spacing on temperature rise. In addition to FC-72, immersion cooling in Novec 649 and HFE 7100 weremodeled. Design guidelines are suggested for dielectric fluid immersion cooled multichip modules.