Tinplate (also known as tinplate) refers to a cold-rolled thin steel plate coated with a very thin layer of metallic tin on both sides, which combines the hardness and strength of steel with the ease of welding, corrosion resistance and bright appearance of tin. Tin plate has the advantages of odorless, non-toxic, light weight, and easy to process and shape. Printing different patterns can also beautify the product, so it has been widely used in the food canning industry, electronic devices, chemical paint and other industries. In the production process of tinplate, after the strip steel is tinned and reflowed, in order to prevent the tin layer from oxidizing and yellowing when the tinplate is stored or the paint is baked, and at the same time improve the sulfur resistance and other properties of the tinplate, it is necessary to The tin plate is passivated.