Reduced Energy Loss via Wetting–Adhesion Relationship in Copper/Prepreg Interfaces for High‐Frequency Communication Systems

This study analyzes the chemical bonding mechanism between conductive Cu foil and dielectric prepreg (PPG) substrate using a silane coupling agent to improve adhesion and optimize signal integrity for high speed printed circuit board (PCB). The silane coupling agent reacts with Cu foil to form Si–O–Cu bonds, and the organic functional groups simultaneously bond with PPG to form strong adhesion. Compared to conventional etching methods, this method provides high adhesion without increasing the roughness of the copper foil surface. Its nonetching characteristic minimizes reflection and attenuation during high‐frequency transmission. Surface energy analysis shows that specific PPG had the lowest polar surface energy, indicating the best interaction with the silane coupling agent. Wetting coefficient analysis shows that PPG with optimized composition had the most balanced interfacial adhesion behavior, which was experimentally verified by peel test results with the highest adhesion due to the formation of strong Si–O–Cu bonds. Consequently, return loss testing showed that the optimized PPG‐based PCBs maintained good signal integrity upto 40 GHz, an improvement of about 30% over conventional etching. This suggests that the selection of PPG for nonetching silane coupling agents is effective in high‐speed signal transmission applications.