Copper Tungsten is one of the most popular refractory metal-based heat sink materials offered today.  Tungsten copper sheets are made by infiltrating, under vacuum, uniform controlled porous blocks of tungsten with molten copper heat sink material. This results in a material with an interconnected copper matrix that has high thermal conductivity in all axes, low thermal expansion, and good electrical conductivity. Copper content can range between 10% and 25%. These tungsten copper heat sinks can spread the heat from a concentrated heat source and then dissipate the heat through the layers. 

Properties Of Tungsten Copper Heat Sink For Transistor