In the production process of using acid tin plating brightener, sometimes pinholes appear on the surface of the tin plating layer of the workpiece. What is the reason?
1. The cathode current density is too high.In the process of tin plating, if the current density is too high, the coating will be loose, rough, pinholes, and easily scorched at the corners.At this time, the current density should be reduced to the process range.
2. The concentration of tin plating brightener is too high.Tin plating brightener can improve cathodic polarization, which is the role of fine and bright coating.If the concentration of brightener is too high, the coating will be bright and brittle, the coating will have pitting or pinholes, and the bonding force and solderability will be poor.At this time, a small current electrolytic plating solution or activated carbon can be used to treat the tin plating solution.
3. The cathode moving speed is too slow.The acid tin plating process cannot be stirred with air, and the bright plating layer must be obtained by moving the cathode, which can improve the production efficiency.If the cathode moves too slowly, the coating will appear rough, pitted, and pinholes.At this time, the moving speed of the cathode can be appropriately increased.
4. There are too many organic impurities in the plating solution.After the organic impurities in the plating solution accumulate to a certain extent, the color of the plating solution will deepen, the plating solution will be turbid, and the plating layer will be prone to problems such as brittleness, streaks and pinholes.At this time, flocculants or activated carbon can be used to treat the plating solution to reduce the concentration of organic impurities in the plating solution.
Therefore, we need to pay attention to the above four points in the production process of using acid tin plating brightener, which can avoid the phenomenon of pinholes in the coating of the workpiece and reduce the occurrence of failures.