The Research Of Cyanide-free Copper Complex System

Electroplating copper has a very important position in electroplating industry.Up to now,the authorities have repeatedly issued an administrative order requiring the gradual elimination of cyanide plating in the electroplating industry.At present,the process cannot be completely replaced,but according to the requirements of a cleaner production,the process must be cyanide free.So it is urgent to improve and develop the current cyanide free copper plating process.Firstly,the basic formulation of non cyanide electroplating copper was studied,on the basis of the comparative study of cyanide free copper plating system with different complexing agents,the cyanide-free copper plating system with the main coordination agent as succinimide was determined.Based on the screening of auxiliary complexing agent,conductive salt and additives,the optimized compound cyanide free copper plating system and its composition were determined.The optimized solution is: copper sulfate 50 g/L,succinimide 90 g/L,potassium nitrate 20g/L,citric acid 25g/L,triethanolamine 40g/L,potassium hydroxide 40 g/L.Through single factor experiments,the effects of bath composition and process conditions on the gloss of coating,the upper limit of cathodic current density and the current efficiency were determined.Secondly,the basic formulation of non cyanide electroplating copper was optimized,Effects of brightener — 2-mercapto benzimidazole,two selenium oxide and surfactant including Twelve alkyl sodium sulfate and Polyethylene glycol10000 on the gloss of silver coating prepared from cyanidefree system were studied by means of single-factor experiment.And then the optimal composite additive formulated with the given 2 kinds of materials and the combination of the 3 conditions was obtained by orthogonal tests: 2-mercaptobenzimidazole 1.5 mg/L,Polyethylene glycol 10000 40 mg/L.Under this condition,the stability of the plating bath is good,the anti tarnish property of the coating and the dispersing ability of the plating solution are equivalent to that of the cyanide copper plating system.Finally,the performance of the coating and the coating were tested.The bonding strength,hardness,dispersion and porosity were tested.The results show that the bonding strength and hardness of the coating are good,and the porosity and dispersion capacity are all better than those of the basic plating solution.The microstructure of the coating was analyzed by SEM.The results show that the copper plating layer is the flattest and smoothest,The dispersing ability of the plating solution in this system is equivalent to that of the cyanide copper plating system,and the DC deposition rate is up to 10.58mg/(cm2·h),the current efficiency can reach80.6%,and the deposition rate increases with the increase of current density.