Thermal Analysis of Polymer 3D Printed Jet Impingement Coolers for High Performance 2.5D Si Interposer Packages

Bare die liquid jet impingement cooling is an efficient cooling technique that has been successfully applied using various materials to create high performance cooling solutions. 2.5D Si interposer packages with several Si chips integrated side by side are a potential integrated solution for high performance systems. In this paper, we present the design, modeling, fabrication and experimental thermal characterization of 3D-printed impingement coolers applied to 2.5D Si interposer packages that contain two 8×8 mm ² thermal test chips with integrated heaters and sensors. 3D-printing enables to use low cost materials for the cooler fabrication, to print the whole geometry in one piece and to customize the design to match nozzle array to the chip power map. The fabricated coolers have been applied to both lidless packages allowing the cooling solution to be directly applied to the backside of the chips, and to lidded packages that require a TIM between chip and lid. The thermal performance of the impingement cooler, including the chip self-heating and the thermal coupling, has been assessed for both package configurations using CFD simulations and experiments. A design of experiments of the TIM and lid properties has been performed to assess the tradeoff of the beneficial and detrimental impact of the lid for different flow rates, in order to define guidelines for 2.5D interposer package thermal management solutions.