Liquid cooling performance for a 3-dimensional multichip module and miniature heat sink

Measured thermal performance is presented for a single phase liquid-cooled module. Tape automated bonded (TAB) thermal test chips and their associated substrates are stacked in a compact, 3-dimensional liquid tight module. A dielectric liquid, polyalphaolefin (PAO) is forced to flow past the active and inactive sides of the TAB chips. At a volumetric flowrate of 0.05 gallons per minute (gpm) and an estimated pressure loss less than 0.5 psi. the measured junction-to-liquid thermal resistance is 2.0 C/W for a 0.50"×0.50"×0.015" thermal test chip. The thermal resistance was also measured for an indirect liquid cooling approach. PAO was used to cool a miniature sink mounted directly to a 0.50"×0.50" heat source. The heat source was used to simulate the thermal characteristics of a chip carrier package. Overall dimensions of the liquid heat sink measured 1.0"×1.0"×0.28". The measured junction-to-liquid thermal resistance is 0.52 C/W for a flowrate of 0.05 gpm. and for an estimated pressure loss less than 1.0 psi. Numerical computational techniques yielded results which were comparable to the measured thermal resistances for both the 3-dimensional module and the miniature heat sink. Enhanced thermal performance gained by introducing micro encapsulated phase change material to the PAO is estimated for both the 3-dimensional module and the miniature heat sink