Embodiments of a mechanism of thermal isolation for multiple heat-generating devices on a substrate are described. In one aspect, a substrate is configured for a plurality of heat-generating devices to be disposed thereon. The substrate comprises an electrically-conductive layer that is electrically coupled to the heat-generating devices when the heat-generating devices are disposed on the substrate. The electrically-conductive layer is configured to thermally isolate the heat-generating devices such that there is no thermal coupling through the electrically-conductive layer amongst the heat-generating devices.