Simple fabrication and characterization of discontinuous carbon fiber reinforced aluminum matrix composite for lightweight heat sink applications

The constant increase in power and heat flux densities encountered in electronic devices fuels a rising demand for lightweight heat sink materials with suitable thermal properties. In this study, discontinuous pitch-based carbon fiber reinforced aluminum matrix (Al-CF) composites with aluminum-silicon alloy (Al-Si) were fabricated through hot pressing. The small amount of Al-Si contributed to enhance the sintering process in order to achieve fully dense Al-CF composites. A thermal conductivity and CTE of 258 W/(m K) and 7.0 × 10^-6/K in the in-plane direction of the carbon fibers were obtained for a (Al_{95 vol%} + Al-Si_{5 vol%})-CF_{50 vol%} composite. Carbon fiber provides the reducing of CTE while the conservation of thermal conductivity and weight of Al. The achieved CTEs satisfy the standard requirements for a heat sink material, which furthermore possess a specific thermal conductivity of 109 W cm³/(m K g). This simple process allows the low-cost fabrication of Al-CF composite, which is applicable for a lightweight heat sink material.