Thermally managing high-power IC devices through the use of a circuit assembly comprising a ceramic substrate and an organic substrate. The ceramic substrate has at least one circuit component on a first surface thereof and a periphery defining a lateral surface surrounding the first surface. The organic substrate also comprises a first surface and a periphery defining a lateral surface surrounding the first surface. A portion of the lateral surface of the organic substrate is adjacent a portion of the lateral surface of the ceramic substrate so as to define an interface therebetween. At least one conductor common to both the ceramic and organic substrates and bridging the interface therebetween serves to physically connect the ceramic and organic substrates together.