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

小企业创新研究（SBIR）第二阶段项目将开发并展示用于商业化的天然石墨（NG）增强铝（AlGr）。在这个项目中，廉价的天然石墨薄片（NGF）将被制造成预成型，并与Al-Si合金进行压力渗透，形成导热系数（TC）为600 W/mK至750 W/mK，相应热膨胀系数（CTE）为7至4 ppm/K的复合材料。CTE通过控制NGF的体积分数来确定。TC是无氧高导电性（OFHC） Cu的1.5至1.9倍，质量为Cu的25%，体积成本与定制CTE的Cu相当，可实现热效率直接贴装。高TC源于合金中的Si与NGF表面反应形成低热阻SiC界面。这些特性源于创新的预制结构。此外，通过进一步的预成形设计，可以获得准各向同性的TC值（~700 W/mK）。工作温度每降低10摄氏度，电子设备的寿命就会增加一倍。相反，更有效的冷却方案使设备能够在更高的功率密度和更小的空间内制造出更高的性能。在这个项目中开发的材料将以更低的冷却成本实现这种性能增强。拟议的技术将减少电子热管理应用对铜的依赖，并将在空间和军事雷达和通信系统以及激光二极管散热器，笔记本电脑和其他消费电子产品的散热器中得到重要应用。

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.