Interfacial Bonding Enhancement Mechanism of Copper Foil/Poly-Ether-Ether-Ketone Film by Dual Modification with Uv/Ozone and Silane Coupling

Abstract

The copper foil and PEEK film were directly bonded by nanosecond lasers in this study. In order to improve the interfacial bonding strength between copper foil and PEEK, UV/Ozone and silane coupling treatments were proposed to modify the surface of copper foil. The surface of the copper foil was oxidized to Cu2O by UV/ozone treatment. OM, SEM, EDS, FTIR and XPS were used to characterize and analyze the bonding interface and fracture. A 95% improvement in peel strength of the Cu/PEEK joints following treatment with UV/ozone + silane coupling treatments. In addition, the strong hydrogen bond interaction between the copper foil treated with UV/ozone + silane coupling and the PEEK film was demonstrated by the red-shift of the typical functional group wavenumbers. The red-shift of the functional group wavenumbers confirmed that the silane coupling treatment introduced a large number of hydrogen bonds to the interfacial bonding. The mechanism of highest peel strength of UV/Ozone+ATPMS-Cu/PEEK joints was subsequently verified by density functional theory (DFT). The differential charge transfer and binding energies of Cu/silanol and Cu2O/silanol were calculated by densify functional theory (DFT). The results showed that the bonding of Cu2O to silanol was more stable than that of Cu to silanol.

Keywords: copper foil, PEEK, laser joining, UV/Ozone, silane coupling