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.