Substrate thickness optimization for liquid immersion cooled silicon multichip modules

Liquid immersion cooling represents a potential method for meeting the requirements for removal of increasingly high heat fluxes from microelectronic packages. This work explores immersion cooling of densely packed silicon multichip modules and demonstrates that an optimum substrate thickness exists which minimizes the temperature rise at the integrated circuit die sites. A number of examples are given for a range of die sizes, spacings and heat flux conditions based upon the heat transfer characteristics of R-22. At high flux, the required substrate thickness is considerably larger than that of a standard silicon wafer. The techniques developed are applicable to analysis of other coolants and substrate materials