Abstract:The 6-mercapto-1, 3, 5-triazine-2, 4-dithiol monosodium (TTN) compound was used to fabricate an organic film on pure copper. The polymer plating process of TTN on pure copper in Na₂CO₃ aqueous solution and the growth mechanism of poly(6-mercapto-1, 3, 5-triazine-2, 4-dithiol) (PTT) film were studied by means of cyclic voltammetry. The polymer plating under galvanostatic mode at 0.05 mA/cm² was conducted to generate PTT film on pure copper in the same electrolyte with different polymer-plating time. The film mass was determined by electronic balance and the insoluble fraction in tetrahydrofuran (THF) Is tested. The performance of organic film formed on copper surface was investigated preliminarily by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). It is found that a slight peak measured at 0 V vs SCE attributes to the oxidation of copper and generated Cu⁺ or/and Cu²⁺ to produce Cu-TTN complex, then a strong oxide peak is observed at 0.311 V vs SCE due to the polymerization of TTN for the increase of the film thickness. Electrochemical measurement results reveal that 10 min is an optimum polymer-plated time to obtain high quality film. The results of potentiodynamic polarization show that current density decreases from 1.85 μA/cm² for bare copper to 0.168 μA/cm² for polymer-plated copper while polymer-plated time is 10 min. The charge transfer resistances of bare copper and polymer-plated copper are 937 Ω∙cm² and 11.12 kΩ∙cm², respectively. The film capacitor for polymer-plated copper is as low as 1.82 μF∙cm². The EIS results confirm the results of potentiodynamic polarization and reveal that a homogenous and compact film is obtained by polymer plating technique.

Key words: copper; polymer plating; organic film; potentiodynamic polarization; electrochemical impedance spectroscopy