Super High Thermal Conductivity CTE Matched Power Amplifier Packaging: Hybridized Graphite Fiber Reinforced Al and Cu Alloys

An order of magnitude increase in heat flux of multi-die passive heat sink materials is proposed. High performance graphite fiber reinforced aluminum and copper alloys are precisely CTE matched to diverse substrates such as CVD diamond, SiC, Si, GaN,GaAs, alumina and beryllia, by varying the volume loading of planar-isotropic graphite fiber preforms prior to infiltration with molten matrix alloy. By strategically locating oriented thermal pyrolytic graphite (TPG) inserts within the preform,through-plane conductivity is increased more than a factor ten (1300 W/mK). In-plane conductivity to the system sink is increased by a factor of >5 to 1100 W/mK while maintaining CTE matching to the die or substrate. In a second approach, an array ofhighly conductive K1100 graphite fibers formed into stiff wires are inserted into a planar-isotropic graphite preform below the die mounting location prior to metal infiltration. A small volume fraction of K-1100