When we use the matte tin additive to produce, sometimes the coating of the workpiece will have black spots or black spots, which will affect the quality of the coating. What is the reason for this?
1. Contamination of organic matter decomposition products in the plating solution.These organic decomposition products accumulate in the plating solution, which deepens the color of the plating solution and increases the viscosity, which will cause problems such as brittleness, streaks, and black spots in the coating.We should regularly use 1~3g/L activated carbon for adsorption and removal during production.
2. There are metal impurities (such as copper, nickel, zinc, iron and other impurities) in the plating solution.When the plating solution is contaminated by metal impurities, the plating layer will be blackened, resulting in black spots or black spots.We can periodically perform low current density electrolysis on the plating solution to remove some metal impurities.
3. The cathode current density is too small.If the current density is small, the coating will be mixed with heavy metal impurities or particle impurities, resulting in black spots or black spots on the coating.We should check the current density value during production and control it within the process range.
Therefore, we need to pay attention to the above three points when using matte tin additives, which can avoid the phenomenon of black spots or black spots on the coating of the workpiece and reduce the occurrence of failures.