PCM board and VCM board are composite materials obtained by coating paint or film on the surface of thin steel plate, and have good colorability, formability and corrosion resistance. Since the substrate is made of galvanized steel sheet and galvanized steel sheet, the composite material has certain mechanical strength and is easy to process, and is suitable for use as the housing of home appliances. PCM boards and VCM boards have a broad space for development in the field of home appliance applications. In recent years, not only have the purchases of major home appliance manufacturers such as refrigerators, air conditioners, and washing machines increased, but small home appliances such as microwave ovens, water heaters, rice cookers, and electric kettles have also begun to use composite materials. The material serves as the raw material for the production of the shell. The output of these appliances is huge, and the demand for PCM boards and VCM boards can be imagined.