Fabrication, Thermal Conductivity, and Mechanical Properties of Hexagonal-Boron-Nitride-Pattern-Embedded Aluminum Oxide Composites.

As electronics become more portable and compact, the demand for high-performance thermally conductive composites is increasing. Given that the thermal conductivity correlates with the content of thermally conductive fillers, it is important to fabricate composites with high filler loading. However, the increased viscosity of the composites upon the addition of these fillers impedes the fabrication of filler-reinforced composites through conventional methods. In this study, hexagonal-boron-nitride (h-BN)-pattern-embedded aluminum oxide (AlO) composites (Al/h-BN/Al composites) were fabricated by coating a solution of h-BN onto a silicone-based AlO composite through a metal mask with square open areas. Because this method does not require the dispersion of h-BN into the AlO composite, composites with high filler loading could be fabricated without the expected problems arising from increased viscosity. Based on the coatability and thixotropic rheological behaviors, a composite with 85 wt.% AlO was chosen to fabricate Al/h-BN/Al composites. The content of the AlO and the h-BN of the Al/h-BN/Al-1 composite was 74.1 wt.% and 12.8 wt.%, respectively. In addition to the increased filler content, the h-BN of the composite was aligned in a parallel direction by hot pressing. The in-plane () and through-plane () thermal conductivity of the composite was measured as 4.99 ± 0.15 Wm K and 1.68 ± 0.2 Wm K, respectively. These results indicated that the method used in this study is practical not only for increasing the filler loading but also for achieving a high through the parallel alignment of h-BN fillers.