The difference between immersion gold and gold plating on PCB circuit boards

Immersed gold boards and gold-plated boards are commonly used processes for PCB circuit boards. Many customers cannot correctly distinguish the difference between the two. Some customers even think that there is no difference between the two. This is a very wrong view and must be corrected in time. So what impact will these two "golden boards" have on the circuit board?

With today's increasingly sophisticated technical capabilities, IC pins are becoming more and more dense, and it is difficult to flatten the thin-foot pads using the tin spray process, which makes it difficult to weld SMT patches. In addition, the tin spray process makes it difficult to solder SMT patches. The standby life of the board is also shorter, and making PCB a gold-plated board can solve these problems. For some ultra-small surface mount boards such as 0603 and 0402, it plays a decisive role in quality, so the whole board gold-plating is used in high-precision It is more common in ultra-small patch processes. In the sample stage, due to the influence of the component procurement cycle, it usually takes a while after the PCB board is made. The cost of the sample is not much different than that of tin spraying, so everyone chooses gold plating. So what is gold plating? What we mean The whole plate gold plating generally refers to "electroplating gold", "electrolytic nickel gold plate", "electrolytic gold", "electro gold" and "electro nickel gold plate". There is a distinction between soft gold and hard gold (generally hard gold is used for gold Finger), the principle is to dissolve nickel and gold (commonly known as gold salt) in chemical solution, immerse the circuit board in an electroplating vat and turn on the current to form a nickel-gold plating layer on the copper foil surface of the circuit board, electro-nickel gold Due to its high hardness, wear resistance and resistance to oxidation, the coating has been widely used in electronic products.

So what is heavy gold? Immersion gold generates a layer of coating through chemical oxidation-reduction reaction. It is generally thicker. It is a kind of electroless nickel gold layer deposition method and can achieve a thicker gold layer.

The difference between circuit board immersed gold board and gold-plated board:

1. Generally, the thickness of immersed gold is much thicker than that of gold plating. Immersed gold will be golden yellower than gold plating. Judging from the appearance, customers are more satisfied with immersed gold. The crystal structures formed by the two are different.

2. Since the crystal structures formed by immersion gold and gold plating are different, immersion gold is easier to weld than gold plating and will not cause poor welding or customer complaints. At the same time, it is precisely because immersion gold is softer than gold plating, so gold finger plates are generally gold plated, as hard gold is wear-resistant.

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

4. Immersion gold has a denser crystal structure than gold plating and is less prone to oxidation.

5. As the wiring becomes denser, the line width and spacing have reached 3-4MIL. Gold plating is prone to short circuits in the gold wire. The immersion gold plate only has nickel gold on the pad, so there will be no gold wire short circuit.

6. The immersion gold board only has nickel gold on the pad, so the solder resist on the circuit is more firmly bonded with the copper layer. The project will not affect the spacing during compensation.

7. It is generally used for boards with relatively high requirements and good flatness. Generally, immersion gold is used. Immersion gold generally does not cause black pads after assembly. The flatness and service life of the immersed gold plate are as good as those of the gold-plated plate.