Transposable, highly thermal conductive silicone rubber/boron nitride composites with enhanced orientation of BN by multilayer stacked hot pressing according to rheological control

Composites with high out-plane thermal conductivity (TC) and great insulation are essential for thermal management in electronic devices. Herein, a transposable, highly thermal conductive silicone rubber (SR)/boron nitride (BN) composite was fabricated by multi-layer stacked hot pressing, in which the orientation of BN was enhanced based on rheological characterizations. Then the pre-pressed films were stacked under 180 °C to get a full-cured and thick composite. The enhanced orientation of BN and the excellent heat transfer capability of the composites were well verified by SEM, XRD, 2D WAXS, finite element analysis (FEA) and infrared thermography, which resulted in a wonderful thermal pathway and low interfacial thermal resistance. The TC of the composite reached 22.08 W/(m·K), and the high in-plane TC could be converted to high out-plane TC after simple vertically cut due to the flexibility and large thickness of composite. Meanwhile, for the first time, the excellent heat transfer capability of the composite was quantitatively characterized by the characteristic temperature rise time constant (τg). The rheological control was an efficient and potential strategy to get highly thermal conductive composites.