A circuit board assembly with a substrate having a laminate construction of ceramic layers, such as an LTCC ceramic substrate. The substrate is configured for the purpose of improving the thermal management of power circuit devices mounted to the substrate. Thermally-conductive vias extend through the substrate from a first surface thereof to a second surface thereof. A circuit device is mounted to the first surface of the substrate and is electrically interconnected to conductor lines of the substrate. The device is also thermally coupled to the thermally-conductive vias with a first solder material. A heat sink located adjacent the second surface of the substrate is bonded to the thermally-conductive vias with a second solder material, such that the first solder material, the thermally-conductive vias, and the second solder material define a thermal path from the device to the heat sink.