Thermal design for reliability in avionics faces continual challenges from changing power demands due to increased onboard processing and communication capabilities beside size/weight constraints and harsh operating environments. For UAVs, all these factors have added pressure for shorter development time to flight and tighter package size. A new approach to electronics cooling design using FloTHERM® XT addresses the time pressures by bridging the divide between EDA driven development and mechanical engineering processes. This presentation applies this to an avionics cooling bay example. It includes efficient board level layout import from Mentor’s Xpedition® (+ other EDA formats) and using a CAD centric approach to importing or rapidly creating complex enclosure geometry.