Thermally conductive and electrically insulating BNNS/epoxy composites via magnetic orientation

To address the thermal management demands of high-power electronic devices, a magnetic alignment technique was employed to enhance the thermal conductivity of copper-clad laminates (CCLs). Boron nitride nanosheets (BNNS) were functionalized with Fe 3 O 4 nanoparticles via in situ growth, resulting in magnetically responsive nanosheets (mBNNS). These were subsequently incorporated into an epoxy resin (EP) matrix, and composite laminates were fabricated through a combination of magnetic field-guided alignment and hot pressing. At a magnetic alignment duration of 5 hours and a filler loading of 40 wt%, the resulting composite reached a thermal conductivity of 0.95 W·m −1 ·K −1 , which is approximately 380% higher than pure epoxy and 137% higher than that of non-aligned BNNS composites. Moreover, the laminate maintained favorable dielectric and mechanical performance, exhibiting a breakdown strength of 42 V/μm and a peel strength of 1.12 N/mm. These findings indicate that magnetic functionalization combined with directional alignment provides an effective strategy to facilitate phonon transport in BNNS-based composites, offering significant promise for next-generation thermal interface and packaging materials.