Reasons for yellowing of precision stampings
The residual syrup and additives in the interior of the precision stampings are spit out, and the tin layer on which the plating is applied is highly susceptible to corrosion by these materials. Causes surface oxidation and yellowing of the coating.
Insufficient post-treatment and drying of the workpiece can also cause yellowing of the coating.
Adhesion of tetravalent tin, excessive additive, contamination of zinc impurities in the plating bath (less likely), insufficient thickness of the coating, contamination of iron impurities (the phenomenon is not easy to find during electroplating), storage environment. These are the reasons that lead to the yellowing of precision metal stampings.
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