3D Printed Boron Nitride‐Filled Continuous Carbon Fiber/Epoxy Resin Composites With Ultra‐High Thermal Conductivity and Favorable Mechanical Property

With the development of high‐power electronic devices, the demand for polymer composites with superior thermal management and mechanical properties is increasing. In this work, continuous carbon fiber/epoxy resin/hexagonal boron nitride (CCF/EP/h‐BN) composites were fabricated via in situ three‐dimensional (3D) printing. By adjusting the h‐BN content from 0 to 20 wt%, the composites achieved both enhanced interlaminar shear strength (from 53.5 to 60.4 MPa) and a remarkable improvement in thermal conductivity, reaching a peak value of 13.5 W/m·K at 15 wt% h‐BN (129% higher than unfilled CF/EP). Elemental mapping and finite element simulation revealed that increasing h‐BN content promotes the formation of a continuous 3D bridging network, which serves as an efficient thermal pathway and reduces interfacial thermal resistance. The combined experimental and simulation results confirm that the synergistic effect of highly oriented CFs and well‐dispersed h‐BN enables outstanding thermal management and mechanical reliability. This study provides new insights and technical guidance for the structural and functional integration of polymer composites for advanced electronic packaging.