Acid bright tin plating is an important process widely used in the manufacture of electronic, electrical and communication equipment. However, in the actual production process, we often encounter the phenomenon of whitening of plating, which not only affects the aesthetics, but also may adversely affect the functionality. So, what are the reasons for the whitening of the plating layer and how to solve it?
Causes of whitening of plating
1. The composition of the plating solution is unstable:
Additives and electrolytes in acid bright tin plating have an important influence on the stability of the plating solution and the brightness of the plated layer. We found that when the composition ratio of the plating solution is out of balance, or the impurity content in the plating solution is too high, it is easy to generate white spots or cloudy whitening on the surface of the plated layer. Especially when the concentration of tin ions, sulfate ions and organic additives is not normal, it will make the plating layer texture uneven.
2. Inadequate control of process parameters:
In specific operations, small changes in process parameters such as current density, temperature and pH can have an effect on the quality of the plated layer. Too high or too low a current density, operating temperatures outside the appropriate range and abnormal pH values can lead to a reduction in the quality of the coating and the formation of a whitish phenomenon.
3. Inadequate substrate treatment:
Pre-treatment of the substrate is also an important part of the plating quality. Insufficient cleanliness and activity of the substrate may result in poor adhesion of the plating and formation of uneven, thin-colored coatings.
Ways to solve the whitening phenomenon
1. Use a good acid tin plating brightener:
High-performance brighteners can effectively harmonize the chemical reactions in the electrolyte to enhance the brightness and uniformity of the plated layer. An example is Sn-807, an acid tin plating brightener from Bigely, which produces uniform, bright, pure tin deposits over a wide temperature range and has high bath stability to minimize the effects of impurities. In addition, Sn-807 has good corrosion resistance and solderability, which improves the functionality of the coating.
2. Strict control of process parameters:
The control of current density, temperature and pH can be precisely adjusted by means of automated equipment and real-time monitoring to ensure the stability of the process parameters. By optimizing the process parameters, the brightness and uniformity of the plated layer can be substantially improved.
3. Enhancement of pre-treatment processes:
Adequate cleaning and pretreatment of the substrate to ensure that the surface of the substrate is free of oxides and oil can improve the adhesion and brightness of the tin plating layer. Chemical cleaning and oil removal can be used to optimize the surface condition of the substrate.
Conclusion
The problem of whitening of acid bright tin plating layer is mainly caused by unstable composition of plating solution, improper control of process parameters and insufficient treatment of substrate. Through the use of acid bright tin plating brightener such as Bigely Sn-807, strict control of process parameters and strengthening of pre-treatment procedures, the whitening of the plating layer can be effectively reduced and the quality of the plating layer can be improved, thus providing good tin plating products for the manufacture of electronic, electrical and communication equipment.
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