Design Optimization and Characterization of Silicon Microcooler System Through Finite-Element Modeling and Experimental Analyses

As chip power densities are now increasing beyond air cooling limits, a variety of liquid cooling methods are being investigated. The silicon microchannel cooling is an attractive approach due to its high heat transfer coefficient. In this paper, a thermal test chip with heating spots was mounted onto a synthetic diamond heat spreader, and then mounted onto the SMC cooler through the thermocompression bonding process. Finally, this structure was mounted onto the printed circuit board and connected with the manifold. The reliability of the cooler system was investigated through finite-element analysis (FEA) and characterization. Five types of FEA models were conducted considering process flow and application conditions, including shear test model, model of bonding the thermal chip to the heat spreader, model of the whole cooler system assembly, thermomechanical coupling analysis model considering hotspot heating, and temperature cycling reliability test model. Die attach materials were evaluated based on the shear test and modeling results. The cooler system was optimized based on the FEA results to reduce stress and warpage. The thermomechanical coupling simulation was conducted for the cooler system by considering nonuniform temperature distribution due to hotspots and cooling effect. The experimental results showed that the designed cooler system has good performance and reliability thermally and mechanically.