Food-grade electrolytic tinplate is also called tinplate, tin-plated thin steel, and its English abbreviation is SPTE and ETP. Tinplate refers to a cold-rolled low-carbon thin steel sheet or steel strip coated with pure tin on both sides. Tin plating plays a major and important role in preventing corrosion and rust. Food grade electrolytic tinplate has the strength and formability of steel with the corrosion resistance, solderability and aesthetic appearance of tinplate. Most people think that ETP consists of five layers, including base steel, iron-tin alloy, tin, passivation film and oil film. However, some people believe that it is composed of six layers; that is, there is a tin oxide film under the passivation film. Sometimes, the tin oxide film and the passivation film are collectively referred to as the oxide film.