Design and preparation of low-filled magnetic oriented BN@Fe3O4/EP insulating composite with improved thermal conductivity and thermal stability

As an excellent two-dimensional insulating material with high thermal conductivity , high temperature stability and high hardness, hexagonal boron nitride(h-BN) is widely applied in semiconductor manufacturing, aerospace, metallurgical manufacturing and other cutting-edge fields. However, the unique surface structure of h-BN leads to poor lubricity and easy agglomeration, which limits the application of h-BN especially in the field of electronic packaging. To address key issues boosted above, this study designed and prepared the BN@Fe 3 O 4 magnetic insulating particles and doped it into the reduced viscosity epoxy resin to prepare the composites. By selecting appropriate external magnetic field strength and BN@Fe 3 O 4 particles’ content, a novel 3D structure of fillers like dominoes in epoxy resin composite was successfully constructed. The microstructure of the BN@Fe 3 O 4 particles and composites were analyzed, the thermal conductivity, the mechanical and the electrical properties of composites were simultaneously tested. Results manifested that the core-shell structures with BN as core and Fe 3 O 4 as shell was successfully prepared, linking through the PDA middle layer between the BN core and Fe 3 O 4 shell. Under the influence of magnetic orientation, the BN@Fe 3 O 4 magnetic particles were preferred an out-of-plane oriented in the epoxy resin composites, resulted an enormously enhanced on thermal conductivity of composites. At a magnetic field strength of 60 mT and 25 vol% BN@Fe 3 O 4 content, the thermal conductivity of BN@Fe 3 O 4 /EP composites is as lofty as 1.832 W/(m K), which is 1023.46% higher than that of pure epoxy resin. Meanwhile, the thermal stability has also been slightly improved, the elastic modulus and insulation performances remain at the same level.