What are the process differences between PCB circuit board gold plating and immersion gold?
Winnie Tsai
CCS (Cell Contact System for Battery Module) | Flex PCB | Rigid-Flex PCB | SMT | Heater Solution Provider
Gold plating: mainly through electroplating, gold particles are attached to the PCB board, because gold plating has strong adhesion, also known as hard gold, and the gold finger of the memory stick is hard gold, which has high hardness and wear resistance.
Immersion gold: A layer of coating is formed by chemical oxidation-reduction reaction. Gold particles crystallize and attach to the pad of PCB. Because of weak adhesion, it is also called soft gold.
The difference between gold plating and sinking gold:
1. The gold plating process is done before the solder resist, and the green oil may not be cleaned cleanly, and it is not easy to tin; while the immersion gold process is done after the solder resist, and the patch is easy to tin.
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2. Before the gold plating process, it is usually necessary to plate a layer of nickel first, and then plate a layer of gold. The metal layer is copper-nickel-gold, because nickel is magnetic and has an effect on shielding electromagnetic waves. The immersion gold process is to immerse gold directly on the copper skin, the metal layer is copper gold, no nickel, and no magnetic shielding.
3. The process of gold plating and immersion gold is different, and the crystal structure formed is also different. Compared with gold plating, immersion gold is easier to weld and will not cause poor welding. And immersion gold has a denser crystal structure than gold plating, and it is not easy to produce oxidation.
4. The flatness of the gold-plated circuit board is not as good as that of immersion gold. For boards with higher requirements, the flatness is better. Generally, immersion gold is used, and immersion gold generally does not appear black pads after assembly.