Thermal performance of an integral immersion cooled multichip module package

A multichip module (MCM) package which uses integral immersion cooling to transfer heat from the chips to a final heat transfer medium outside the package was constructed. The package is a miniature immersion-cooled system with a pin-fin condenser which can be operated in either the submerged or vapor-space condensing mode. Sixteen chips were bonded on a 57 mm² alumina substrate carrying copper/polyimide thin film interconnect. Tests of the thermal performance of the system show that it is capable of handling over 160 W power with chip thermal resistances as low as 2 K-cm²/W provided by the immersion cooled portion of the thermal path. Tests performed with the module fully powered and with subsets of the chips powered indicate that the heat transfer coefficient is similar in all partially powered modes. Data taken with condenser temperatures ranging from 20 to 50°C were used to obtain a performance map delineating the heat transfer regimes in the module and the limits imposed by critical heat flux and condenser performance