Enhancement of Tensile Strength in Electrodeposited Copper Foils Using Cetyltrimethylammonium Bromide as a Suppressor

This study investigates the influence of long-chain quaternary ammonium surfactant cetyltrimethylammonium bromide (CTAB) on the performance of copper foil, including tensile strength and aqueous wettability. The addition of CTAB leads to an average ultrahigh tensile strength of 711 MPa and elongation of 7.32% of copper foil. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Electron backscatter diffraction (EBSD) analyses revealed that CTAB significantly reduced copper grain size and improved surface uniformity. Electrochemical tests confirmed the suppressing effect of CTAB on cathodic copper deposition. Density functional theory (DFT) calculation and in situ infrared spectroscopy (in situ FTIR) analysis show that adsorption of CTAB on the copper substrate suppresses the electroreduction of Cu²⁺ to Cu and increases the cathodic polarization, thus effectively refining the grain structure. This work validates CTAB as a potent suppressor for improving the mechanical properties and wettability of copper foils.