Active cooling substrates for thermal management of microelectronics

Heat removal in printed wiring boards (PWB) is primarily accomplished through conduction. This work presents a microelectromechanical system (MEMS) device comprised of an active cooling substrate (ACS) designed and fabricated to add fluidic cooling functionality to the PWB. Thermal management is enhanced through the additional heat convection mode. Synthetic jet technology makes the compact, but easily integrated, MEMS cooling device possible. The fluid control unit, a synthetic jet, has been implemented in an epoxy-glass printed wiring board by multilayer lamination. An air reservoir is drilled through the core of printed wiring board. A flexible polymeric diaphragm and a low profile electromagnetic driver create an active pumping system to produce vibrating air jets downstream of microfluidic channels which transports heat generated by hot microelectronic components. Test heater chips have been directly die attached to the substrate. The integrated packaging system has been characterized mechanically, electrically, and thermally. Peak jet velocities of 14 m/s and average jet velocities of approximately 3 m/s have been achieved at actuator powers of 60 mW. This integrated active cooling substrate has the potential for broad applications in thermal management at the system packaging level.