Research Of The High Speed Bright Tin Plating With Environmentally Friendly

Methyl sulfonic acid is a kind of high boiling point organic acid and strongelectrolyte, also called methane sulfonic acid (MSA). MSA tin plating liquid hasstrong stability, and the corrosion of equipment, the advantages of good environmentalperformance and attention, and gradually replace phenol sulfonic acid tin plating liquid.Methyl sulfonate tin plating liquid can be in wide current density range for coating, andhas a good plating and deep plating ability, able to plating under high current density,sedimentation speed, operating at high temperatures, methyl sulfonic acid solution canmaintain high concentration of metal ions, basically can be applied to high speedelectroplating process.Secondary manufacture was used as the electrode materials in this study, by usingthe constant current method, through the single factor relative experiments, wedeveloped a good performance of tin fluid formulation and process parameters of theperformance of plating solution (environmental performance, scattered ability, coveringpower and so on); coating performance (salt spray test, Tafel, impedancespectroscopy). And we optimized the composition of Methyl sulfonate tin plating liquidand electroplating process through orthogonal test. The optimization results is that theenvironmental performance of MSA Tin plating liquid is better than the PSA Tinplating liquid which is used now, its scattered ability and covering power is good. Theformula of the plating liquid is that concentration of Sn2+is40mL/L, and methanesulfonic acid is35mL/L, additive B is13mL/L, additive A is10mL/L. The processparameters is that the current density is28A/dm-2, speed is3m/min, temperature is40℃at20s. We get a result that the corrosion resistance of high speed electroplating tinis much more better than common electroplating through salt spray and electrochemicalworkstation test. The lack of reactive ion in cathode zone causes the concentrationpolarization and the large gap of coating grain which causes coating corrosion resistantalways happen in electrode reaction in common electroplating.In order to study the additives (dispersing agent, brightener and stabilizer) in MSAtin plating liquid on the performance of the plating solution and plating, through thesingle factor experiment (Hull Cell, cathodic polarization curves, cyclic voltammetriccurves, macro),we screened the type and content of dispersants and brighteners, and analyzed the influence of polarization performance and the electrodepositionprocess.The experimental results showed that the dispersant was AES and OP-10compound additive,and brightener was acetone.Through the single factor experiment(hydrogen peroxide accelerated oxidation, heat resistance experiment, cathodicpolarization curve),we screened the type and content of stabilizer, and analyzed theinfluence of polarization performance and the electrodeposition process.Theexperimental results showed that stabilizer was the of mixture hydroxylamine sulfateand ascorbic acid.Considering solution stability, the plating solution was measuredcontinuously by chemical titration experiment to determine the content of Sn2+andSn4+in the plating solution.In order to further improve the corrosion resistance of tinplate, using the softmelting technology, salt spray test and electrochemical workstation test,and the singlefactor experiment(heating power, heating time, quenching water temperature) studiedthe corrosion resistance of tinplate, determining the best process was: the heating powerof410w, the heating time for9s, water quenching temperature ranging30~50℃. Thecorrosion resistance of was closely related to the pore on the surface of the tinplate.Theflow leveling effect of soft melt made the big hole on the surface of the coating reduce,the smaller pores form, the pore on the surface of the tin coating decrease,and thecorrosion resistance improve.With the decreasing of water quenching temperature,thecorrosion area on the surface of tin layer gradually decreased,indicating that number ofpinhole gradually reduced,and improved its corrosion resistance.