Development of Methane Sulfonic Acid Tinplating Bath

This paper describes the development and the performances of a new tin electroplating bath, which greatly reduces environmental loads and also improves the productivity. The conventional tin electroplating bath had a problem of heavy environmental loads. On the contrary, the methane sulphonic acid (MSA) based bath, which is used for soldered can material productions, has a merit of light environmental loads, but it is difficult to apply to the production of general tin electroplated steels because of the differences in required properties. Based on the MSA bath of light environmental loads, a new electroplating bath has been developed by finding new polyethylene glycol (PEG) contained additives, which make possible the balance of light environmental loads and productivity. The main characteristic of the new additive is that it contains two kinds of PEGs of high and low molecular weight, which dramatically improve the performance in a high current density range, although the bath containing either of the two PEGs is inferior to the conventional halogen based bath. This new tin electroplating bath containing two kinds of PEGs has been used in National Steel Corporation in US and has shown high performances.