A thermal conductor is made of copper and carbon nanotubes powders that are compressed together and then cold rolled into sheets for aligning the carbon nanotubes for providing a composite matrix having a low coefficient of thermal expansion, high thermal conductivity, and high electrical conductivity, for preferred use as a conducting heat sink, such as a laser submount, for heat sinking dissipation and electrical grounding of high-power electrical components and circuits, such as a laser diode.