Solderproof green paint covers most of the copper surface of the circuit, revealing only terminal contacts for parts welding, electrical testing and circuit board insertion.The end point shall be provided with additional protective layer to avoid oxide production at the end point of connecting the anode (+) during long-term use, which will affect the stability of the circuit and cause safety concerns.
[electroplated hard gold] a nickel layer and a high chemical blunt gold layer are plated on the insertion end of the circuit board (commonly known as gold finger) to protect the end point and provide good connection performance, which contains appropriate amount of cobalt and has excellent wear resistance.
[spray tin] cover the welding end of the circuit board with a layer of tin-lead alloy by hot air leveling to protect the end of the circuit board and provide good welding performance.
[pre-welding] cover a layer of anti-oxidation pre-welding film on the welding end of the circuit board in the way of impregnation, temporarily protect the welding end and provide relatively smooth welding surface before welding, so as to have good welding performance.
[carbon ink] a layer of carbon ink is printed on the contact end of the circuit board in the way of screen printing to protect the end and provide good connection performance.