Magnetically Oriented 3D-Boron Nitride Nanobars Enable Efficient Heat Dissipation for 3D-Integrated Power Packaging

Increasing power density and miniaturization in three-dimensional (3D) packaged power electronics demand innovative thermal management. Yet, the thermal performance of electrically insulated packages for power electronics is currently limited by the ultralow thermal conductivity of conventional thermal interface materials (TIMs) and their poor ability of directing heat current to heat sink. Herein, we have prepared a highly thermally conductive and electrically insulating TIM composite based on boron nitride nanobars (BNNB). The polar characteristics of the B–N bond in the BNNB outer tube wall-derived h-BN nanosheets facilitate the adsorption of magnetic particles. Modulating the arrangement of 3D-BNNB by an external magnetic field improves the thermal conductivity of composite up to 3.3 W m –1 K –1 at a concentration of 40 wt %, 17.8 times higher than the pure epoxy and also exhibiting significant anisotropy. Moreover, the composite shows a high stiffness of 510 MPa and a high resistivity of 27.2 MΩ·cm, demonstrating excellent mechanical and electrical insulating characteristics. Infrared thermography results show that the surface temperature of the composite depends on the orientation of BNNB and its interfacial interaction with the epoxy resin. The magnetic field-oriented modulation of 3D-BNNB can offer a promising solution to achieve efficient thermal management of 3D-integrated power packaging.