An adhesion promoter layer for high-frequency printed circuit boards (PCBs) via initiated chemical vapor deposition

Official URL: https://dx.doi.org/10.1016/j.mtcomm.2024.109559

Establishing robust bonding between dissimilar materials, particularly metal and polymer composites is a significant challenge in electronics. This study focuses on enhancing the interfacial adhesion strength between super flat copper foil and ultra-low-loss dielectric material, crucial for optimizing the performance of high-frequency printed circuit boards (PCBs). Despite the common practice of mechanically treating the copper surface, which increases the surface roughness and significantly deteriorates signal transmission for high-frequency applications, herein, we present a novel approach involving a thin adhesion promoter layer coating onto an ultra-low-profile copper foil using the one-step, solventless technique of initiated vapor deposition (iCVD). Poly(glycidyl methacrylate) (pGMA) is utilized as the adhesion promoter and deposited on a super-flat profile copper surface via iCVD. The results demonstrate that the straightforward iCVD pGMA deposition significantly improves adhesion performance to 0.68 N/mm between the copper foil and prepreg, representing a 70 % improvement compared to 0.4 N/mm for the untreated copper surface. This research introduces a promising, scalable, and environmentally friendly adhesion promoter layer for copper-clad laminates (CCLs), particularly in the manufacturing of high-performance composite materials for the electronics industry.