Synergistic enhancing effect of tungsten-copper coated graphite flakes and aluminum nitride nanoparticles on microstructure, mechanical and thermal properties of copper matrix composites

Thermal management materials with high thermal conductivity (TC), adjustable coefficient of thermal expansion (CTE) and excellent mechanical properties have promising applications in the electronic packaging and high-power density equipment fields. In this work, we have developed a novel strategy for tungsten-copper coated graphite flakes and aluminum nitride nanoparticles reinforced copper matrix composites (GFs(W–Cu)/AlN/Cu composites) fabricated by vacuum hot-pressing sintering. Herein, tungsten-copper coated graphite flakes (GFs(W–Cu)) were prepared by impregnation reduction and ultrasonic-assisted electroless plating, in which W–Cu coating improved interfacial bonding and realized metallurgical-physical synergy. Meanwhile, the AlN nanoparticles reinforced Cu flakes (AlN/Cu) were prepared by high energy ball milling, where AlN nanoparticles were evenly dispersed in the Cu matrix and played the role of pinning boundary and refining grain. Effects of nano-AlN with different volume fractions on the mechanical and thermal properties of GFs(W–Cu)/AlN/Cu composites were studied as well. As for the mechanical properties, the in-plane, through-plane flexural strength and tensile strength of GFs(W–Cu)/1.5AlN/Cu composite reached 276.7 ± 4.5, 390.6 ± 4.5 and 136.1 ± 3.0 MPa respectively, which increased by 96.8%, 283.7% and 120.7% than those of the GFs(W–Cu)/Cu composites. In terms of the thermal properties, the in-plane TC of GFs(W–Cu)/1.5AlN/Cu composite is 617.8 ± 12 Wm−1K−1, while the through-plane CTE ranging 25–200 °C is 4.9 ± 0.2 ppmK-1. In conclusion, the GFs(W–Cu)/AlN/Cu composites provide a huge potential for design and application in the thermal management materials.