Mechanical modeling and characterization of silicon micro cooler

As chip power densities are now increasing beyond air cooling limits, a variety of liquid cooling methods are being investigated. The silicon microchannel cooling (SMC) is an attractive approach due to its high heat transfer coefficient. In this study, a thermal test chip with heating spots was mounted onto a synthetic diamond heat spreader, and then mounted onto the SMC cooler through temperature compression bonding (TCB) process. Finally, this structure was mounted onto the printed circuit board (PCB) and connected with the manifold. The reliability of the cooler system was investigated through mechanical modeling and characterization. Four types of models were conducted considering process flow and application conditions, including model of bonding thermal chip to heater spreader, model of whole cooler structure assembly, shear test model, and thermal-mechanical coupling analysis model considering hot spot heating. The cooler system was optimized based on finite element modeling results to reduce chip stress and package warpage. Die attach materials were also evaluated based on shear test and modeling results. The thermo-mechanical coupling simulation was conducted for cooler system by considering temperature non-uniform distribution due to hot spot and cooling effect. Results show that the designed cooler system meets the requirement of performance and reliability thermally and mechanically.