Enhanced thermal conductivity of epoxy composites by constructing aluminum nitride honeycomb reinforcements

Recently, anisotropic polymer/ceramic composites have attracted great attention because of their high thermal conductivity for the extensive usage in microelectronic devices. However, further enhancement of their thermal conductivity is a great challenge due to the presence of interface thermal resistance and lack of efficient heat conduction pathways. Herein, epoxy (EP)/aluminum nitride honeycomb (AlN–H) composites were fabricated through a two-step method including freeze-casting of the AlN–H reinforcements and EP infiltration. The results showed that the vertically aligned and interconnected thermal conductive networks contributed to the enhanced thermal conductivity and thermal stability of the composites with the increase in AlN loading. The composites exhibited maximal thermal conductivity values of 9.48 W m−1 K−1 and 4.45 W m−1 K−1 in the directions parallel and perpendicular to the AlN–H channels, respectively, at AlN loading of 47.26 vol%. The composites displayed excellent heat dissipation performance when they were attached to a working CPU, which indicates significant promise for application in thermal interface materials. [Display omitted] •Anisotropic epoxy/aluminum nitride honeycomb composites were successfully fabricated by freeze-casting and EP infiltration.•Vertically aligned thermal conductive networks significantly enhanced the thermal conductivity of the composites.•The microstructure and thermal properties of the composites are controlled by the solid loading of freezed slurries.•The composites exhibited excellent heat dissipation performance for CPU.