Study On Chromium-free Passivation Technology And Mechanism Of Electrolytic Copper Foil

Electrolytic copper foil is one of the basic materials of electronic industry.As the basic conductive raw materials for the production of printed circuit boards and lithium ion batteries,electrolytic copper foil is the carrier for the mutual assembly of various electronic components,known as the"neural network"of electronic product signals and power transmission.The passivation treatment of electrolytic copper foil is an important part of the production of electrolytic copper foil.The surface passivation treatment of electrolytic copper foil determines the corrosion resistance and high temperature oxidation resistance of electrolytic copper foil.The current industry-university-research cooperative enterprise Jiangxi Xinborui Technology Co.Ltd.has problems such as pollution of the environment due to chromium in passivation solution,poor resistance to high temperature oxidation of copper foil,and insufficient corrosion resistance.This leads to difficult sewage treatment,and the performance of electrolytic copper foil is reduced during storage,transportation,and use.Therefore,it is very necessary to study the passivation process that is environmentally friendly and has excellent passivation performance.This paper focuses on the process and mechanism research of molybdenum-phosphorus passivation solution.The chemical immersion process and electrochemical passivation process of molybdenum-phosphorus-chromium-free passivation are studied by the combination of orthogonal experiment and single-factor optimization experiment.Passivation process results Combined with the surface morphology,SEM,XPS and EDS results of electrolytic copper foil,the film formation process of the two methods of molybdenum and phosphorus passivation was analyzed;the composite passivation process of rare earth cerium salt and molybdenum phosphorus passivation was studied;Electrolytic copper foil performance after passivation processes such as molybdenum-phosphorus chemical immersion passivation,molybdenum-phosphorus electrochemical passivation,molybdenum-phosphorus-cerium passivation,and chromium-containing passivation.The following conclusions were drawn:（1）The optimal process parameters of molybdenum-phosphorus passivation chemical soaking are molybdate 12g/L,phosphate 16g/L,temperature 55℃,soaking time 60s,p H value 6.The optimal process parameters of molybdenum-phosphorus electrochemical passivation are molybdate 10g/L,phosphate 20g/L,p H value 10,current density 12.5m A/cm²,temperature 50℃,treatment time 40s.（2）The film-forming mechanism of molybdenum-phosphorus passivation is the combined action of adsorption and diffusion.The film-forming driving force of molybdenum-phosphorus chemical passivation is temperature gradient,while the film-forming driving force of molybdenum-phosphorus electrochemical passivation is temperature gradient and Common interaction of currents.Under the action of phosphate,molybdate is preferentially adsorbed to the protruding active sites on the surface of the electrolytic copper foil,and then diffuses.In the process of adsorption and diffusion,it reacts with the copper foil matrix to form insoluble substances deposited on the surface of the electrolytic copper foil.These insoluble substances together with Cu O and Cu₂O constitute a molybdenum-phosphorus-chromium-free passivation film.（3）Rare earth cerium can improve the passivation performance of molybdenum and phosphorus electrochemical passivation.The best addition method of rare earth cerium salt is ceria,and the addition amount is 2g/L.（4）Molybdenum-phosphorus chemical immersion passivation,molybdenum-phosphorus electrochemical passivation,and molybdenum-phosphorus-cerium passivation have good passivation performance and can meet the performance requirements of the electrolytic copper foil industry.Among them,molybdenum-phosphorus-cerium passivation has The best high-temperature oxidation resistance,no oxidative discoloration occurs when treated at 200℃for 1h,the tensile strength can reach 353 MPa,the elongation is 12.2%,and the gloss is 221Gu.Has a very good industrial application prospects.The high-temperature oxidation resistance of electrolytic copper foil after molybdenum-phosphorus chemical immersion passivation and molybdenum-phosphorus electrochemical passivation treatment is better than that of chromium-containing passivation.