Enhanced through-plane thermal conductivity and high electrical insulation of flexible composite films with aligned boron nitride for thermal interface material

Abstract

Thermal interface materials (TIMs) with high thermal conduction and electrical insulation properties in through-plane direction are highly desirable in high-power and dense electronic devices. Thus a generalizable step-by-step orientation method without chemical modification or special treatment is adopted to prepare the composite films (boron nitride/poly (vinylidene fluoride) (i.e. x-BN/PVDF)). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that quite part of the BN platelets (BNs) are aligned well along the through-plane direction. A thermal conductivity of 3.50 W m−1 K−1 is obtained at a BN loading of 30 wt%, which has been improved by 1448% compared with the pure PVDF (0.226 W m−1 K−1). The volume resistivity and alternating current (AC) resistivity of 30-BN/PVDF sample are 6.51 × 1013 Ω·cm and 4.56 × 107 Ω·m (1 kHz), respectively, indicating much potential as high-frequency insulation material. In addition, the strong thermal conduction capability of the composite film is demonstrated by comparing temperature changes, which shows the importance of higher through-plane thermal conductivity in TIM applications.