Variable Fin Density Flow Channels for Effective Cooling and Mitigation of Temperature Nonuniformity in Three-Dimensional Integrated Circuits

The surface temperature of integrated circuit (IC) chips cooled with a single-phase liquid flow increases along the flow direction following the increase in the liquid temperature. Increasing the heat transfer coefficient along the flow direction is an effective way to enhance the cooling performance while mitigating the temperature nonuniformity and high pressure drop concerns. This investigation evaluates numerically the cooling performance of different flow channel designs suitable in 3D IC applications with channel heights restricted to 100 μm. Internal configurations featuring offset strip fins with variable fin density and variable spacing ribs were studied in an effort to minimize the temperature nonuniformity while maintaining a relatively low pressure drop. The performance of 13 different designs for the variable-fin-density configuration and three different rib configurations have been evaluated and compared with two baseline cases, corresponding to a smooth flow channel and a flow channel with continuous fins. All of the analyzed internal configurations are contained within a flow channel of 100 μm height and 910 μm width. A coolant chip formed by nine flow channels for the dissipation of 200 W of a 3D IC with a surface area of 1 cm² is the base for this investigation. The best performing configuration resulted in a temperature variation of less than 30 K with a pressure drop of 34 kPa as compared to a temperature variation of 38 K and a pressure drop of 144 kPa with continuous fins and 51 K and 21 kPa for a smooth flow channel.