Sandwich Architecture Disentangles Thermal Transport and Interfacial Adhesion Tradeoff in Polytetrafluoroethylene...

Efficient thermal management and reliable interfacial adhesion remain challenging for high-power, high-frequency copper-clad laminates (CCLs) due to the intrinsic trade-off between thermal conductivity and bonding strength in conventional polymer composites. Here, a functional-gradient sandwich architecture polytetrafluoroethylene (PTFE) based CCL is developed to decouple heat transport and interfacial bonding. The laminate consists of a central thermal conductive (TC) layer and two adhesive layers. The proposed architecture introduces synergistic functional regions with tailored filler networks. Large spherical boron nitride (SBN) particles construct interconnected three-dimensional thermal pathways in TC layer, whereas hybrid small sized hexagonal boron nitride (hBN) and silicon nitride (Si₃N₄) fillers are incorporated into the adhesive layers to enhance mechanical interlocking with copper foils and preserve certain thermal transport capability. Meanwhile, the low-polarity PTFE matrix and electrically insulating ceramic fillers with optimized compositions maintain the intrinsic dielectric stability. In addition, a thickness-dependent thermal transport model is established to correlate effective thermal conductivity with the relative layer thickness. The optimized sandwich CCLs achieve high thermal conductivity (3.96 W/m K), strong peel strength (1.5 N/mm), and ultralow dielectric loss (<0.0005), providing a general structural strategy to overcome the intrinsic trade-off between thermal transport, interfacial adhesion and dielectric reliability in polymer-based electronic substrates.