Interface engineering of Cu foil–prepreg systems by controlling silane terminal groups and wettability

The interfacial adhesion between Cu foil and prepreg is crucial for ensuring the chemical reliability of multilayer structures. In this study, silane-based adhesive systems were used to control CuMeX–prepreg adhesion by systematically varying the silane adhesive and solvent compositions. Contact angle measurements and surface tension analysis were performed to quantify wettability and interfacial characteristics, and the wetting coefficient was used to evaluate interfacial preference. Notably, changes in silane chemistry and solvent ratio were found to significantly affect surface tension components and wetting behavior, resulting in different fracture modes at the CuMeX–prepreg interface. Specifically, silane adhesives with unbalanced interfacial interactions resulted in adhesive fracture, whereas those with balanced interactions resulted in cohesive fracture. Peel-off tests were conducted on CuMeX–prepreg assemblies with different prepreg materials, revealing that adhesion strength varies depending on the surface properties of the prepreg, even under identical silane conditions. These findings provide a quantitative basis for correlating surface tension balance, wetting coefficient, and adhesion behavior in silane-mediated CuMeX–prepreg systems.