In the production process of using acid tin plating additive, black spots are easy to appear on the workpiece coating. After washing, black spots still exist. What is the reason?
According to the site experience and the characteristics of acid tin plating additive Sn-807, Bigolly Technology analyzed the following three main reasons:
1. Product substrate problem.For example, in the process of tin plating for brass parts, the zinc in brass dissolves relatively quickly, and the zinc enriched near the base material is easily reduced to elemental sulfur by sulfuric acid and remains on the surface of the workpiece, so that after the workpiece is exposed to high temperature or sunlight, the tin sulfide black brown deposit will form on the surface of the coating, which is the black spot we see.
2. The cathode density is too low.In the process of tin plating, the current density is small, and the coating is easy to be mixed with particle impurities and form black spots on the coating surface.Therefore, the current density should be controlled within the process range during production.
3. The plating solution is contaminated by impurities.Due to the continuous accumulation of organic decomposition products in the plating solution, the color of the plating solution will deepen and the viscosity will become larger, so that the workpiece coating is prone to stripes, black spots and other phenomena.In addition, if there are metal impurities (such as copper, nickel, zinc, iron and other impurities) in the plating solution, the workpiece coating will also appear black spots.During the production process, the plating solution should be regularly treated with activated carbon or electrolytic treatment to reduce the impact of impurities on the workpiece coating.
Therefore, we should pay attention to the above three points in order to reduce the occurrence of faults and improve production efficiency when using acid tin plating additives.If you are interested in acid tin plating additives, please contact Bigolly customer service for free samples and detailed technical information!
If you want to know more about tin plating,you can click to view "Common problem".