Electrochemical Behavior Of Copper In 1-hydroxyethylene-1,1-diphosphonic Acid (HEDPA) Baths

Copper cyanide electrodeposition is the most widely used on the bottom of iron,zinc alloy substrate materials in copper electrodeposit process.However,concerns over the biological toxicity of cyanide have stimulated an extensive search for satisfactory alternative electrolytes.At present,HEDPA cyanide-free copper electrolyte have been to provened can replace the Copper cyanide electrodeposition,because its advantages,such as simple component,stable coordination agent,excellent bonding force with basal body of iron.At present,introduction of additives or second ligand in copper plating system is the main directions for improving plating performance,but less study of theory on copper anode dissolve in HEDPA system.The anodic dissolution electrochemical behavior of copper electrode in non-cyanide alkaline electrolyte containing 1-hydroxyethy-lene-1.1-diphosphonic Acid?HEDPA?as a complexing agent was investigated.By cyclic voltammetry studied on electrochemical behavior of copper electrodes,and used x-ray photoelectron spectroscopy analysis the dissolution products of copper electrode under different potentials.The results showed that in the 1-hydroxyethylene-1,1-diphosphonic Acid?HEDPA?baths,the first oxidation peak was diffusion-controlled,associated with the formation of Cu₂O.The second oxidation peak come from generating CuO and the third peak was the formation of CuO/Cu?OH?₂ compound.By polarization curve testing,as the temperature increases,the copper electrode anodic polarization curves rise,the degree of polarization gradually decreased,the current density increases,causes the dissolution of copper electrode smoothly;Activation energy calculations show that the activation energy is high at high potential,indicate in high potential form a passivating film.Different pH of copper anodic polarization curve shows that the high pH value,the high degree of polarization,copper electrode surface dissolved is blocked.Different ratios anodic polarization curves can be found that 1:3 ratios proportion is the most appropriate.Use polarization curve testing and electron microscopy pictures of different amounts of TEA in HEDPA copper system,we hypothesized that the appropriate amount of TEA will make copper plating more delicate,but the TEA will lead to abnormal copper anode dissolution,TEA added 15ml/L is suitable.By different CO₃^2-consistency of copper electrode polarization curve,current-time curve and electric mirror pictures we can see,as carbonate root addition increased,the polarization curve of copper anode reduced,the cycle VA curve also shows,with the CO₃^2-join,the Cu₂+restore potential moved negative and the peak current increased and anode peak area became variable large.This indicated that the CO₃^2-addition will make copper dissolution increased,with the rise of CO₃^2-content,there are more and more holes in the copper anodes electron microscopy pictures,and by over time SEM pictures contrasting,we found the copper anode surfaces dissolved normally,it shows CO₃^2- will make anodic dissolution smoothly,as a second ligand is not a depleting agent.