What is the difference between gold plating and immersion gold

Immersion gold adopts the method of chemical deposition. A layer of coating is formed by chemical redox reaction. Generally, the thickness is thicker.

Gold plating uses the principle of electrolysis, also known as electroplating. Most other metal surface treatments are also electroplated.

In actual product applications, 90% of gold plates are immersion gold plates, because the poor weldability of gold-plated plates is his fatal shortcoming, and it is also the direct reason why many companies give up the gold-plating process!

The immersion gold process deposits a nickel-gold coating with stable color, good brightness, smooth coating and good solderability on the surface of the printed circuit. Basically it can be divided into four stages: pre-treatment (oil removal, micro-etching, activation, post-dipping), nickel immersion, gold immersion, post-treatment (waste gold washing, DI washing, drying). The thickness of immersion gold is between 0.025-0.1um.

Gold is used in the surface treatment of circuit boards, because gold has strong conductivity, good oxidation resistance, and long life. It is generally used in key boards, gold finger boards, etc. The most fundamental difference between gold-plated boards and immersion gold boards is that gold-plated is hard Gold (wear-resistant), immersion gold is soft gold (not wear-resistant).

1. The crystal structure formed by immersion gold and gold plating is different. The thickness of immersion gold is much thicker than that of gold plating. Immersion gold will be golden yellow, which is more yellow than gold plating (this is one of the methods to distinguish gold plating and immersion gold). a), the gold-plated ones will be slightly whitish (the color of nickel).

2. The crystal structure formed by immersion gold and gold plating is different. Compared with gold plating, immersion gold is easier to weld 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 immersion gold is softer than gold plating, so the gold finger of immersion gold plate is not wear-resistant (the disadvantage of immersion gold plate).

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

4. Compared with gold plating, immersion gold has a denser crystal structure and is not easy to produce oxidation.

5. With the increasing requirements of circuit board processing accuracy, the line width and spacing have reached below 0.1mm. Gold plating is prone to short circuit of gold wires. The immersion gold plate only has nickel gold on the pad, so it is not easy to produce a short circuit of gold wire.

6. The immersion gold board only has nickel-gold on the pad, so the combination of the solder mask on the circuit and the copper layer is stronger. The project will not affect the spacing when compensating.

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

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