First of all, let’s first introduce what is Shen Jin? The copper on the circuit board is mainly copper. The brazing joints are easily oxidized in the air. This causes electrical conductivity, that is, poor tin or poor contact, which reduces the performance of the board. Therefore, the brazing points need to be surface treated. The immersion gold is gold-plated on it. Gold can effectively block copper metal and air to prevent oxidation. Therefore, immersion gold is a kind of surface oxidation treatment. It is covered with a layer of gold on the surface of copper by chemical reaction. Gold.