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PCB Tech

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PCB Tech

PCB Tech

What is circuit board gold plating and immersion gold? What is the difference between the two?

The surface treatment process of the circuit board includes: anti-oxidation, tin spray, lead-free tin spray, immersion gold, immersion tin, immersion silver, hard gold plating, full board gold plating, gold finger, nickel palladium gold OSP, etc., these are relatively common The surface treatment process, but there are many friends who don’t know what gilding and immersion gold are and the difference between them, the following editor will talk about it in detail.

gold-plated circuit board

Introduction to gold plating and immersion gold for circuit boards

  The gold particles are mainly attached to the pcb board by electroplating. Because the gold plating has strong adhesion, it is also called hard gold. The gold finger of the memory stick is hard gold, which has high hardness and wear resistance.

   Immersion gold:

   is to generate a layer of plating through a chemical oxidation-reduction reaction method, and the gold particles are crystallized and attached to the pads of the pcb. Because of the weak adhesion, it is also called soft gold.

The difference between gold-plated circuit board and immersion gold
1. Immersion gold is different from the crystal structure formed by gold plating. Immersion gold is much thicker for gold than gold plating. Immersion gold will be golden yellow and more yellow than gold plating (this is one of the ways to distinguish between gold plating and immersion gold. One), the gold-plated will be slightly whitish (nickel color).

  2. The crystal structure formed by immersion gold and gold plating is different. Immersion gold is easier to weld than gold plating and will not cause poor welding. The stress of the immersion gold plate is easier to control, and for products with bonding, it is more conducive to the processing of bonding. At the same time, it is precisely because the immersion gold is softer than the gilding, so the immersion gold plate is not wear-resistant as the gold finger (the disadvantage of the immersion gold plate).

  3. The immersion gold board only has nickel and gold on the pads. In the skin effect, the signal transmission is on the copper layer and will not affect the signal.

   4. Immersion gold has a denser crystal structure than gold plating, and it is not easy to produce oxidation.

  5. As the precision requirements for circuit board processing are getting higher and higher, the line width and spacing have been below 0.1mm. Gold plating is prone to short circuit of gold wire. The immersion gold board only has nickel gold on the pad, so it is not easy to produce gold wire short circuit.

   6. The immersion gold board only has nickel and gold on the pads, so the solder mask on the circuit and the copper layer are more firmly bonded. The project will not affect the spacing during compensation.

  7. For the boards with higher requirements, the flatness requirements are better. Generally, immersion gold is used, and immersion gold generally does not appear black pad phenomenon after assembly. Immersion gold plate has better flatness and service life than gold plate.