Multi-objective optimization of a chip-attached micro pin fin liquid cooling system

Abstract

This study explores heat transfer from a chip-attached micro pin fin cooling device undergoing water jet impingement where the silicon chip is in direct contact with the cooling liquid. Directly attaching the micro pin fins onto the chip surface is a new packaging technique that eliminates the contact and sequential conduction resistance of thermal interfaces, which are still used in conventional electronic packages. A multi-objective optimization is solved to minimize the cooling device’s thermal resistance and pressure drop as response parameters. The influence of design parameters, such as pin fin cross section, fin spacing and the fin height profile, on the response parameters is investigated using computational fluid dynamics (CFD) and full factorial design of experiment (FFD). The optimization study is accomplished in two parts. In the first part, the shape optimization is performed by a traditional weighted sum approach using an iterative JAYA algorithm. The shape optimization problem is also solved using modern optimization algorithm of NSGA-II. The results of both approaches are in a close agreement. In the second part, an optimization of the fin height profile is solved using an Artificial Neural Network (ANN) combined with an elitist NSGA-II. The overall analysis demonstrates that the optimized cooling device can surpass its initial working design in thermal and hydraulic performance. Hence, there is excellent potential for the use of lightweight and compact designs in Heterogeneous Integration (HI) applications.