We all know that, in order to get PCB a good conductivity, the copper on the PCB is mainly electrolytic copper foil, and the copper solder joints in the air exposure time is too long easy to be oxidised, which will cause poor conductivity or poor contact, reducing the performance of the PCB, so we need to make surface treatment for copper solder joints. Immersion gold is plating gold on it, gold can effectively make a block layer between the copper metal and air to prevent oxidation, so the immersion gold is an anti-oxidation surface treatment, is through a chemical reaction on the surface of the copper foil covered con un sottile strato d'oro, chiamato oro ad immersione.