What kinds of processes are there for tin plating? How to choose tin plating process

Tin is a silvery white metal, which is non-toxic and has good weldability and ductility. Widely used in electronics, food, automobile and other industries. According to the PH value of the bath, the tin plating process can be divided into acidic bath process and alkaline tin plating process. The advantage of acidic tin plating is its high plating speed. The coating is bright and fine, and has good deep plating ability. The plating solution has strong tolerance to impurities, and room temperature operation saves energy. Disadvantages are poor dispersion of plating solution, high porosity of coating, soldering is not as good as alkaline tin plating, and bivalent tin is hydrolyzed. Acid tin plating can be divided into sulfate tin plating, fluoborate tin plating and chloride tin plating due to different conductive media. The cost of sulfuric acid tin plating is low, the plating solution is easy to control, and the coating is bright and fine, but the dispersion ability is poor. The market is most widely used. The advantages of fluoborate tin plating are high plating speed, high current and good bath stability. Widely used in continuous electroplating of wire and strip. The disadvantages are high cost, high toxicity and difficult wastewater treatment. Chlorinated tin plating is mainly used for particle tin plating, which has the advantages of low cost, stable plating solution and white coating. The disadvantage is that the current is not large. The advantages of alkaline tin plating are: simple composition, good dispersion ability of plating solution, fine coating, few pores and good brazing performance. The disadvantages are: high working temperature, large energy consumption, narrow current application range, low current efficiency, inability to obtain bright coating, small hard coating and great influence on anode behavior. Alkaline tin plating can be divided into stannate tin plating and pyrophosphate tin plating because of the different complexing agents used. Stannate tin plating has a simple composition, the main salt is sodium stannate and part is potassium stannate. The latter has higher solubility, higher current density, higher production efficiency and higher cost. The complexing agent is sodium hydroxide (or potassium hydroxide). The coating obtained by this method is white and not bright. The market is gradually replaced by acid bright tin plating. The use of pyrophosphate tin plating is limited because of its high cost. But its PH value is weakly alkaline, which is suitable for electroplating on aluminum alloy and zinc alloy parts.