PVD (Physical Vapor Deposition) refers to the process of using physical processes to achieve material transfer, transferring atoms or molecules from the source to the surface of the substrate. Its function is to spray certain particles with special properties (high strength, wear resistance, heat dissipation, corrosion resistance, etc.) on a matrix with lower performance, so that the matrix has better performance. Basic PVD methods: vacuum evaporation, sputtering, ion plating (hollow cathode ion plating, hot cathode ion plating, arc ion plating, active reactive ion plating, radio frequency ion plating, DC discharge ion plating).