SBIR Phase II: Ultra High Thermal Conductivity Aluminum/Graphite Composites from Low Cost Natural Graphite

The Small Business Innovation Research (SBIR) Phase II project will develop and present for commercialization natural graphite (NG) reinforced Al (AlGr). In this project, inexpensive natural graphite flake (NGF) will be manufactured into a preform and pressure infiltrated with Al-Si alloys to form composites with thermal conductivities (TC) from 600 W/mK to 750 W/mK and corresponding thermal expansion (CTE) from 7 to 4 ppm/K. CTE is specified by controlling volume fraction of NGF. TC is 1.5 to 1.9 times oxygen free high conductivity (OFHC) Cu at 25% of the mass and comparable volumetric cost to Cu with customized CTE enabling thermally efficient direct die attach. High TC results from reaction of Si from the alloy with NGF surfaces to form low thermal impedance SiC interface. These properties result from innovative preform architecture. In addition, quasi-isotropic TC values (~700 W/mK) are achievable through further preform design. For every 10C decrease in operating temperature, the life of an electronic device is doubled. Conversely, more efficient cooling schemes enable devices to be manufactured with higher performance at higher power densities and in smaller spaces. The materials developed in this project would enable such performance enhancements, and at lower cooling costs. The proposed technology would reduce the dependence on copper for electronic thermal management applications and would find serious application in space and military radar and communication systems as well as laser diode heatsinks, heat spreaders for notebook computers and other consumer electronics.