What are the effects of metallic impurities, such as iron and copper ions, on the quality of the plated layer during the production process using acid tin plating brighteners?
When iron ions in the plating solution exceed 0.5g/L or copper ions exceed 0.6g/L, the plating layer will darken and porosity will increase. They are often the result of plated parts falling into the tank and not removed in time. Arsenic and antimony are equally harmful, which may be brought in by the high content of impurities in sulfuric acid.
In order to reduce the erosion of steel or copper hangers in the acidic tin sulfate plating solution, to avoid contamination of the plating solution by iron ions and copper ions impurities, hangers should be plated with a layer of nickel before use.
In order to maintain good electrical conductivity of the plated parts, the cathode and anode copper bar should be scrubbed frequently, but do not make the copper green fall into the plating tank.
If black spots or black streaks appear in the plating, the anode plate also tends to turn black when plating is not possible in low current density areas. These indicate that copper and other heavy metal impurities have contaminated the plating solution. When there are too many copper impurities, they can be removed by energizing at a small current density of 0.15~0.20 A/dm2.
In order to minimize the generation of metal impurities, when using acid tin plating brighteners, Bigely engineers recommend that tin anodes be 99.99% pure tin and that anode current densities not exceed 2A/dm2. Outside of the anode, an anode bag of Vinylon or Polyester should be attached to prevent anode sludge from entering the plating solution during the anode dissolution process, which can cause roughness in the plated layer or produce burrs. When tin plating production is not carried out, the anode should be regularly brushed and the anode bag rinsed.
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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, Bigely has over 20 years' experience in electroplating additives production and own production base of 5000 square meters. We can produce 15,000 tons of electroplating additives every year, which can fully meet the needs of customers.
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