During the application of sulfate matte tin additives, sometimes the covering power of the coating is poor, which affects the quality of the coating. What is the reason for this?
1. The concentration of stannous sulfate is too high. Stannous sulfate is the main salt of the plating solution. Within the allowable range, it can increase the cathode current density and accelerate the deposition rate. However, if the concentration is too high, the covering power of the plating solution will decline, the color of the coating will be darker, the crystallization will be rough, and the bright areas will shrink.
2. The concentration of sulfuric acid is too low. Sulfuric acid has the functions of preventing the hydrolysis of stannous acid, reducing the activity of stannous ions, improving the conductivity of the plating solution and enhancing the anode current efficiency. When the concentration of sulfuric acid is too low, stannous ions are prone to oxidize into tetravalent tin, which prevents the plating solution from becoming turbid and reduces the covering power of the coating.
3. The concentration of the matte tin additive is too low. The matte tin additive has the functions of enhancing cathodic polarization, refining the crystallization of the coating, and improving the dispersion ability of the plating solution. When the concentration of the matte tin additive is too low, the dispersion ability of the plating solution is poor, and the covering ability of the coating will deteriorate.
4. The temperature of the plating solution is too high. During production, the temperature of the plating solution should be controlled within the process range. When the temperature is too high, the plating solution is prone to become turbid and have sediment. The coating will be relatively rough, with poor covering ability. Problems such as darkening, mottling, and decreased solderability of the coating may occur.
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Guangdong Bigely Technology Co., Ltd. ,founded in 2003, is a high-tech enterprise integrating R & D，production, sales and service, specializing in the production of electroplating additives. As a famous electroplating additives source manufacturer in China, our products are widely used to meet the plating needs of different industries and exported to many countries from all over the world. They can meet the environmental protection standard after use, mainly used in automobile parts, sanitary ware, electronic products, hardware, furniture, building accessories and other fields.
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