A new technique for diamond heat sink fabrication is described in which the diamond is embedded in a copper rod. This technique affords greater flexibility in the design of device packaging and choice of diamond size. Comparisons between thermal measurements of avalanche diode chips fabricated on copper and embedded diamond heat sinks confirm that the latter dissipates twice as much heat as the former. This development is not limited to avalanche diodes as the heat sink design is independent of the chip or package shape.