Manufacture of High Thermal Conductivity (+750W/mK) Cu-graphite Composites Using Particulate Additions and In-Situ Carbide Formation to Improve Wetting

摘要

Conventional copper alloys are unacceptable as heat spreaders for many high power electronic designs due to excessive thermal expansion and insufficient heat transfer. High thermal conductivity (+1000W/mK) graphite integrated into Cu to create Cu-graphite MMC's provides: adjustable CTE to match specific system/package designs, compatibility with conventional metallization/solder joining, and the ability to steer heat in a preferred direction. Cu-graphite composites can be manufactured by melt processing if the graphite surface is modified so that it wets with the liquid Cu. Pressure infiltration casting was performed with graphite after surface modification to improve wetting by: particulate additions of Mo and W, and in-situ CrC formation during infiltration. High thermal conductivity Cu-graphite MMC's were fabricated with graphite content between 53 and 68 volume% and an adjustable CTE between 7.09 to 15.08{sup}(-6)/°C. Adjustable CTE, low cost and a thermal conductivity between 325.4 and 779.7 W/mK are driving commercialization for thermal management in high power electronics.