Fabrication of Aligned BNNS Composites with Excellent Thermal Conductivity via a Low Magnetic Field.

Electrical devices that are small and have high power provide heat management issues. The rate of rapid heat dissipation is currently limited by the thermal conductivity of thermal interface material (TIM) and their capacity to direct heat toward heat sinks. Here, magnetically assisted orientation casting (MAOC) is used to fabricate high thermal conductivity composites based on a boron nitride nanosheet (BNNS). These composites can transmit heat into specific areas by spatial orientation of magnetically functionalized BNNS microplatelets. With a 50% concentration of magnetic responsive BNNS (M-BNNS) in the composite, the network of polyurethane (PU) and the high degree of alignment all contribute to the extraordinarily high thermal conductivity along the alignment direction, up to 1.21 W m-1 K-1. This method is unique in its use of a peak magnetic field to establish a vertical alignment of BNNS. The rational design of TIM microstructures to strategically route heat offers a viable approach to effective thermal management in integrated circuits.