In the production process of using acid tin plating brightener, since the workpiece is easy to bring Fe2+ into the plating solution during the pickling process, the Fe2+ solution produced by the corrosion of the steel equipment is easily brought into the plating solution.So what effect does Fe2+ have on the performance of the tin plating layer?
According to the field experience and the characteristics of the product acid tin plating brightener Sn-819, Bigolly Technology has made an analysis, mainly for the following three reasons:
1. The effect of Fe2+ on the porosity of the coating.With the continuous increase of Fe2+ concentration in the plating solution, the porosity of the tin plating layer will gradually increase.When the Fe2+ concentration exceeds 10g/L, the porosity of the coating will increase sharply, and the quality of the coating will decrease.Therefore, it is necessary to maintain the Fe2+ concentration not more than 10g/L.
2. The effect of Fe2+ on the corrosion resistance of the coating.With the continuous increase of Fe2+ concentration in the plating solution, the corrosion resistance of the coating will gradually decrease.This is because the increase of Fe2+ concentration increases the porosity of the coating, and the corrosion resistance of the coating also decreases.
3. The effect of Fe2+ on tin slime.Fe2+ has a catalytic acceleration effect on the formation of tin slime.Fe2+ and Sn2+ in the bath will compete for dissolved oxygen in the bath, resulting in the production of Fe3+, Fe3+ reacts with Sn2+, and when Sn4+ is formed, Fe2+ will be generated again, forming such a redox cycle process.In the process of tin plating, Fe2+ is affected by the reduction of cathodic current, which will corrode the coating of the tin plate, thereby reducing the current efficiency of tin plating.
Therefore, in the production process of using acid tin plating brightener, Fe2+ in the plating solution should be treated regularly to reduce its influence on the performance of the tin plating layer.