Thermally conductive poly(ether ether ketone)/boron nitride composites with low coefficient of thermal expansion

The substantial heat generation due to miniaturization and high-degree integration of electronic devices is one of the major issues to facilitate efficient thermal management in power electronics. Though epoxy-based composites have shown great interest in different applications such as laminated circuit board, electronic component encapsulations, and potting, they have low application temperature (up to 150 °C) and higher mismatch of coefficient of thermal expansion (CTE) between the heat source and heat sink. Here, poly(ether ether ketone) (PEEK) composites reinforced with hexagonal boron nitride (hBN) nanoplatelets have been developed by liquid mixing and re-melting method for a step change in composite materials with lower CTE and significantly improved thermal dissipation capability. The lowest achieved CTE is 2.1 µm m⁻¹ K⁻¹, and the highest thermal conductivity is 1.04 W m⁻¹ K⁻¹ in PEEK/hBN composites at 30 wt% hybrid hBN content (hBN platelets with two different sizes, i.e. 70 nm and 500 nm, taken as 1:1 weight ratio), due to the formation of thermally conductive inter-filler networks. The composites show negligible variation in K with the working temperature up to 250 °C. The developed composites also exhibit excellent electrical insulation properties; thus, they will have good potential in thermal management for power electronic applications. Graphical abstract: [Figure not available: see fulltext.]