Polymer-hexagonal boron nitride (BN) composite has become an ideal thermal interface material (TIM) for electronic devices because of its high thermal conductivity and superior electronic insulation. However, owing to the 2D shape and chemical inertness of BN filler, the vertical alignment of BN and the huge thermal resistance are current challenges, which hinder the efficient heat transfer of polymer/BN composites. Herein, by a novel non-solvent induced phase separation process combined “in-situ welding” strategy, we present the fabrication of silicone rubber film with finger-like continuous BN-welded filler skeleton, which reveals a high through-plane thermal conductivity of 15.4 W m⁻¹K⁻¹ at only ∼ 15 wt% BN. Finite element simulation and nonlinear model analyses theoretically confirm that the filler-to-filler interfacial thermal resistance (ITR) is halved after in-situ welding process. In addition, thanks to the excellent compressibility and conformability of silicon rubber matrix, the contact thermal resistance (<70 Kmm²W⁻¹) of this composite film is much lower than that of the commercial thermal pad under different pressure. The proposed strategy opens up a novel and high-throughput preparation strategy for the high-performance TIM for modern electronic devices.

聚合物-六方氮化硼（BN）复合材料以其高导热性和优异的电子绝缘性成为电子器件理想的热界面材料（TIM）。然而，由于 BN 填料的二维形状和化学惰性，BN 的垂直排列和巨大的热阻是当前的挑战，阻碍了聚合物/BN 复合材料的高效传热。在此，通过一种新型的非溶剂诱导相分离工艺结合“原位焊接”策略，我们展示了具有指状连续 BN 焊接填料骨架的硅橡胶薄膜的制备，其具有高的通面导热率15.4 瓦·米⁻¹ K ⁻¹仅约 15 wt% BN。有限元模拟和非线性模型分析从理论上证实，在原位焊接过程后，填料间界面热阻 (ITR) 减半。此外，得益于硅橡胶基体优异的压缩性和贴合性，该复合薄膜在不同压力下的接触热阻（<70 Kmm ² W ^-1）远低于商用导热垫。所提出的策略为现代电子设备的高性能 TIM 开辟了一种新颖的高通量制备策略。