Droplet-based Hot Spot Cooling Using Topless Digital Microfluidics on a Printed Circuit Board

Thermal management is a critical issue in integrated circuit (IC) design. With each new IC technology generation, feature sizes decrease, operating speeds increase, and package densities increase, contributing to larger power consumption and elevated die temperatures. Higher temperatures are detrimental to circuit behavior and reliability. Furthermore, hot spots due to spatially non-uniform heat flux in integrated circuits can cause physical stress and further reduce reliability. We have demonstrated a cooling method on a “digital microfluidics” platform whereby discrete droplets are manipulated to adaptively cool simulated hotspots using microliter-sized droplets. Cooling droplets are actuated independently in user-defined patterns over an array of electrodes by electrowetting, eliminating the need for external pumps. We explore the cooling ability of these droplets by varying the temperature of the hot spot and the effective flow rate of the droplets. The results presented here suggest that digital microfluidics is an attractive platform for adaptive hot spot cooling.