Screening And Process Optimization Of Sulfate Bright Tin Plating Additive

Sulfate bright tin plating process is widely used in electronics and food industry for its strengths such as bright coating,fine crystal,good solderability,simple bath composition,high current efficiency,easy to obtain raw materials,simple operation and many other advantages.So it received extensive attention in the word.However,China's research on additives for sulfate bright tin plating is started relatively late,and the type of additive is relatively little,leading to tin plating solution of many problems have not been resolved,such as the electroplating solution is unstable,easy turbidity,plating temperature range is narrow and additives are highly toxic etc..In this way,it is necessary to develop new sulphate bright tin plating additives and their solutions to improve the problem while promoting the localization of tin plating solution.In this paper,the content of sulfate bright tin plating additives were determined and the process conditions were optimized by Hull Cell test and the test of bath performance.The optimum compositions and technological parameters were as follows:H2SO4 100mL/L,SnSO4 30 g/L,C10H10O 0.1 g/L,NP-10 2 mL/L,OP-10 0.5 mL/L,C6H5NO2 0.3 g/L,C6H5COOH 1.8 g/L,C4H4O6KNa 0.8 g/L,C4H6O6 3 g/L,C2H2O4·2H2O 3 g/L,C6H8O6 3 g/L,temperature 20 ?,time 5min,current density 1.5A/dm2.The tin layer obtained by using the recipe and the process conditions can cover the entire specimen under the Hull groove test,the coating reaches the second order light,and the surface has no defects in the national standard.The performances of the bath was tested.The results showed that the bath is stable and natural placement for more than two months without deterioration,the dispersion capacity is as high as 88-94%,the coverage is as high as 100%,and the current efficiency is almost 100%,in addition,the bath can greatly increase the polarization of the cathode.So the bath performance is good.The coating performance was tested and found that the coating between the substrate and the solderability are well,both of them meet the national standard.The results of SEM show that the whole area of the coating is flat and uniform,and there is no problem such as unevenness of surface and roughness due to the occurrence of stripe in the form of hydrogen,and the grains are small and dense.