a circuit assembly containing a surface mount ic package wire bonded to a substrate and configured to conduct heat from the package into a heat sink through a heat - conducting member instead of the substrate . the package contains an ic device with input / output pads on a surface thereof that are connected with leads to conductors on the substrate . the heat sink is located adjacent the package so as not to be separated from the package by the substrate . the heat - conducting member is positioned adjacent the surface of the device opposite its input / output pads , and is bonded to the device and heat sink to provide a heat path between the package and heat sink that does not pass through the substrate .