LAUSR

Now, composite films exhibiting high in‐plane thermal conductivity have received considerable attention as potential thermal interface materials. However, for real‐world thermal management applications, there is a growing need for soft TIMs with higher through‐plane thermal conductivity. This study is centered on the fabrication of flexible composite film materials with a densely packed filler arrangement using a mass‐producible melt‐processing technique. The composite film is composed of PW/POE as the matrix, spherical Al2O3 as the filler, incorporates high thermal conductivity two‐dimensional fillers BN or GNPs, with graphene nanoplatelets (GNPS) enveloping the surface of the Al2O3 particles to create a closely integrated structure with excellent structural stability. The resulting flexible composite film demonstrates a through‐plane thermal conductivity of 9.24 W/mK and a minimal contact thermal resistance of 2.83 × 10−4 m2·K/W, alongside remarkable flexibility characterized by a low Young's modulus of 0.2 MPa. Experimental demonstrations indicate the robust thermal management potential of the developed composite film, positioning it as a promising solution for advanced electronic packaging technologies.