Deposition kinetics analysis of electroless copper using the EDTA/THPED dual-ligand system

To enhance the regulation of the electroless copper plating reaction, an EDTA/THPED dual-ligand system was established, and the deposition kinetics and control steps of the system were analyzed based on Arrhenius and empirical kinetics formulas. The deposition kinetics and rate-determining step of the EDTA/THPED dual-ligand electroless copper system were analyzed based on Arrhenius and empirical dynamics formulas. The results show that the average activation energy E_a of the electrochemical reaction of the dual-ligand system was 15.2 kJ/mol, which is much lower than the activation energy E_a of 60.9 kJ/mol of the EDTA single system. The OH^- concentration has a different effect on the deposition process of the binary system relative to the single system; that is, C(OH^-) can promote the reaction velocity of the binary ligand system while retarding the single ligand system. The impact of the main components on the kinetics of electroless deposition is listed as follows: C(Cu²⁺) > C(OH^-) > C(HCHO) > C(L). The mixed potential test shows that the deposition reaction is controlled by the diffusion process of copper ions. The deposition kinetic model of electroless copper solution was obtained in a dual-ligand system.