Point-line-plane topological thermal network constructed composite film with concurrent high thermal conductivity and electrical safety performance for electronic heat dissipation

The rapid miniaturization and high integration of high-power electronics exacerbate heat accumulation during operation, triggering device instability, shortened service life, and leakage or short-circuit hazards. Traditional carbon-based thermal interface materials (TIMs) suffer from an inherent trade-off among thermal conductivity (k), electrical insulation, and mechanical flexibility, failing to meet the stringent thermal management demands of advanced electronics. Herein, a multifunctional composite film with a point-line-plane multidimensional thermal-conduction network (TCN) is fabricated via vacuum filtration and hot pressing, using boron nitride nanosheets (BNNS), multi-walled carbon nanotubes (MWCNTs), and spherical boron nitride (SBN) as core fillers. The structural complementarity and interfacial synergy of multidimensional fillers optimize the overall performance of the composite film. The optimized film achieves favorable in-plane and through-plane k of 16.77 and 2.98 W/m·K, respectively, while maintaining an elongation at break of 9.6%. Insulating BN-based frameworks disrupt continuous MWCNT conductive pathways to ensure electrical insulation, whereas MWCNTs and SBN act as interlayer bridges to construct integrated 3D TCNs for efficient heat dissipation. This work provides an effective strategy to optimize the performance of conventional carbon-based thermal materials and offers a facile, tunable route for designing high-efficiency, electrically insulating TIMs for potential flexible electronics.