Boron nitride microsphere/epoxy composites with enhanced thermal conductivity

Abstract

As modern electronics are developed towards miniaturisation, high-degree integration and intelligentisation, a large amount of heat will be generated during the operation of devices. How to efficiently remove needless heat is becoming more and more crucial for the lifetime and performance of electronic devices. Many efforts have been made to improve the thermal conductivity of polymer composites, which is an important component of electronics. Herein, the authors report on preparation of boron nitride micosphere/epoxy composites. The cross-plane thermal conductivity of the resultant composites is up to 1.03 Wm-1 K-1. This is attributed to the thermally conductive network formed by the peeled hexagonal boron nitride flakes. Thanks to the superior thermal stability of boron nitride micosphere, the boron nitride micosphere/epoxy composite shows a decreased coefficient of thermal expansion (53.47 ppm/K) and an increased glass transition temperature (147.2°C) compared with the pure epoxy resin. In addition, the boron nitride micosphere/epoxy composite exhibits a lower dielectric constant compared with that of the hexagonal boron nitride/epoxy composite. This strategy can potentially pave the way for the design and fabrication of materials with high cross-plane thermal conductivity and lower dielectric properties.

Thermal Conductivity and Cure Kinetics of Epoxy-Boron Nitride Composites—A Review

“…Similar to Gaska et al, Sun et al [ 128 ] compared composites fabricated with up to 40 wt.% of larger (30 μm) spherical particles with those fabricated with smaller (18 μm) platelets and found that the thermal conductivity was higher for the larger spherical particles. For example, at 40 wt.% the thermal conductivity was 1.03 W/mK for the spherical particles in comparison with 0.86 W/mK for the platelets.…”

“…The findings of Gaska et al [ 81 ], Huang et al [ 91 ] and Sun et al [ 128 ] demonstrate an increase of thermal conductivity with increasing particle size, but it is not possible to draw any unequivocal conclusions from them about the effect of particle size, as there are other intervening factors. On the other hand, Hutchinson and co-workers [ 63 , 64 , 65 , 66 , 67 ] conducted a systematic study of the effects of both BN particle size and shape.…”

Recent Progress in the Study of Thermal Properties and Tribological Behaviors of Hexagonal Boron Nitride-Reinforced Composites

“…Achieving a continuous high TC in both out-of-plane and in-plane direction is challenging for bulk layered materials. Based on recent studies, a 3D segregated filler structure has shown to be promising in supplying uniform TC over both directions [55][56][57]. As an example, integration of a 3D segregated structure of h-BN fillers with epoxy resin has been shown capable of enhancing TC [58].…”

Optimization of Boron Nitride Sphere Loading in Epoxy: Enhanced Thermal Conductivity and Excellent Electrical Insulation

“…In addition, h-BN belongs to crystals of a 2D layered structure, and manifest a significant anisotropy in physical properties including thermal conductivity and coefficient of thermal expansion (CTE) [33,34]. Boron nitride spheres aggregated by h-BN sheets retain the advantages of h-BN, such as high thermal conductivity, low thermal expansion coefficient and good electrical insulating property, as well as the additional isotropous properties [35]. Further, the BN fillers aggregated by h-BN sheets more easily form an effective heat flow path than randomly laid BN platelets [36].…”