The Interface Strengthening and Mechanism of Polytetrafluoroethylene/Copper Foil Composites with Ultra-Low Dielectric Loss

Polytetrafluoroethylene (PTFE) is widely applied in copper-clad laminates for high-frequency communication due to its extremely low dielectric constant and dielectric loss. However, bonding it to other materials without affecting its dielectric properties is challenging due to its ultralow surface energy. This study used polyfluoroalkoxy (PFA), a fluorinated polymer, as a bonding layer to enhance the interfacial adhesion while maintaining other composite properties. Plasma modification was then applied to further strengthen the PTFE/PFA/copper interface. Experimental and calculation results indicate that longer treatment durations and higher power increase surface polar group concentration, thereby improving the adhesive strength without altering the dielectric properties of the composites. The interfacial peel strength under optimized conditions increased from 0.0413 to 0.574 N/mm, representing a 1389.8% increase. This research presents a simple and effective strategy for manufacturing PTFE-based laminates with promising interface strength and dielectric properties, showing significant potential for high-frequency applications.