Exfoliated hexagonal boron nitride-based polymer nanocomposite with enhanced thermal conductivity for electronic encapsulation

Hexagonal boron nitride (h-BN) nanosheet is a novel high thermal conductivity and high aspect ratio filler that has the potential to substantially enhance the thermal conductivity of polymer composites. We prepared h-BN nanosheet by liquid exfoliation of bulk h-BN flakes, and demonstrated the enhanced thermal conductivity of its epoxy composite. It is found that the enhancement of thermal conductivity by using h-BN nanosheet is substantial at low filler loadings. At a loading of 5 wt%, the thermal enhancement factor is 113% for exfoliated h-BN nanosheets, and is only 28% for h-BN control. It is also noted that the effect of using h-BN nanosheets becomes less obvious at high filler loading probably due to the large thermal boundary resistance. Infrared thermal imaging measurement confirmed that the resulting h-BN nanosheet/epoxy nanocomposite can successfully reduce the thermal resistance between Cu-Si interfaces when being used as thermal conductivity adhesives. Further, detailed characterizations on the flowability, thermomechanical properties and moisture adsorption, etc. revealed the promising application of the BN nanosheet/epoxy nanocomposite for electronic encapsulation.