Rreparation and characterization of Alkyl phosphoric self-assembled monolayers on electroless copper film surface

Self-assembled monolayers of alkyl phosphonic acids were prepared on the surfaces of freshly made-up electroless copper plated samples by pulsed constant-voltage/potentiostatic pulse enhancement in order to analyse the electrochemical, spectral properties and wettability of self-assembled monolayers. Results showed that the corrosion currents of those self-assembled monolayers decreased 98.4% in 1% alkyl phosphonic acid solution, and their electrochemical impedance increased correspondingly, compared with those of blank samples. In that case, self-assembled monolayers inhibited the anodic process of the corrosion reaction, which lead to interfacial charge transfer instead of oxygen diffusion. FT-IR spectroscopy confirmed that the alkyl phosphonic acid monomolecular film was successfully assembled on the surfaces of electroless copper plated samples, and their corresponding absorption peak of became relatively larger after enhanced by the pulsed constant-voltage. Contact angle test indirectly also affirmed that the alkyl phosphonic acid solution was assembled into films, samples' hydrophilic surface converted into hydrophobic, and the contact angle θ of the self-assembled monomolecular films increased by 39° after the pulsed potentiostatic enhancement treatment, indicating that the pulsed potentiostatic enhancement made the assembled film denser.