Thermally conductive and electrically insulating thermal interface materials (TIMs) are highly desired for electronic cooling. To improve heat transfer efficiency, thermally conductive fillers with a high loading content have been incorporated into the polymer-based TIMs. However, this is usually at the expense of the interfacial thermal resistance reduction and reliability. In this study, vertically aligned boron nitride nanosheet films (VBNFs) have been prepared by a scalable microfluidic spinning process and template-assisted chemical vapor deposition conversion method. A further high-temperature annealing was applied to achieve high crystallinity. VBNFs have been applied as fillers to fabricate TIMs and achieve a superior through-plane thermal conductivity of 6.4 W m-1 K-1 and low modulus of 2.2 MPa at low BN loading of 9.85 vol %, benefitting from the well-aligned vertical sheet structure and high crystallinity. In addition, the fabricated TIMs present high-volume resistivity and breakdown strength, satisfying the electrical insulation demands. The high thermal conductivity and low modulus contribute an outstanding cooling performance to the TIMs in the heat dissipation application for high-power LEDs. This template-assisted conversion technology for the fabrication of orientated BN nanosheets structure and the prepared high-performance TIMs pave the way for efficient thermal management of high-power electronics.
Keywords: boron nitride; electrical insulation; thermal interface materials; thermal management; vertical alignment.