Copper plating is an important component of the protective and decorative copper/nickel/chromium system. Flexible and low porosity copper plating plays an important role in improving the adhesion and corrosion resistance between plating layers. The copper plating layer is also used for local impermeable carbon, metallization of printed board holes, and as a surface layer for printing rollers. The chemically treated colored copper layer, coated with an organic film, can also be used for decoration. Currently, the most commonly used copper plating solutions are cyanide plating solution, sulfate plating solution, and pyrophosphate plating solution.