PCB Tech - The difference between FPC gold plating and Immersion gold

With the development of electronic products gradually becoming shorter, smaller, lighter and thinner, the advantages of FPC flexible circuit boards are becoming more and more obvious, and the market demand is also increasing. At present, the surface technology of FPC flexible boards includes sinking gold, sinking tin, Gold-plated, tin-plated, OSP, etc., then immersion gold and gold-plated are both gold, what is the difference between them, the following editor will talk about it in detail.

Text label: FPC soft board

With the development of electronic products gradually becoming shorter, smaller, lighter and thinner, the advantages of FPC flexible circuit boards are becoming more and more obvious, and the market demand is also increasing. At present, the surface technology of FPC flexible boards includes sinking gold, sinking tin, Gold-plated, tin-plated, OSP, etc., then immersion gold and gold-plated are both gold, what is the difference between them, the following editor will talk about it in detail.

1. What are the aliases for gold-plated and Immersion Gold?

Gold-plated: hard gold, electric gold

Immersion gold: soft gold, chemical gold

2. The origin of the alias?

Gold plating: The gold particles are attached to the FPC board by electroplating. All are called electro-gold. Because of the strong adhesion, it is also called hard gold. The gold finger of the memory stick is hard gold, which is wear-resistant. The bound FPC is generally also Use gilding.

Immersion gold: Through a chemical reaction, gold particles crystallize and adhere to the pads of the FPC board. Because of the weak adhesion, it is also called soft gold.

3. How does gold plating and immersion gold affect the patch?

Gold-plating: Do it before solder mask. After doing it, it may not be cleaned with green oil, and it is not easy to tin.

Immersion gold: After doing solder mask, the patch is easy to tin.

4. The process sequence is different?

Gold plating: do this process before doing solder mask, because gold plating requires two electrodes, one is the FPC board and the other is the tank. If the FPC board is finished with the solder mask, it will not conduct electricity, and it cannot be plated with gold.

Immersion gold: After the solder mask is done, the chemical method is the same as that of sinking tin. The place where there is a leakage of copper is attached to the gold.

5. How does gold plating and immersion gold affect electrical appliances?

Gold plating: Before gold plating, it is necessary to plate a layer of nickel, and then a layer of gold. The metal layer is copper-nickel-gold, because nickel is magnetic and has an effect on electromagnetic shielding.

Immersion gold: Immerse gold directly on the copper skin, the metal layer is copper gold, no nickel, and no magnetic shielding.

6. How to distinguish between gold-plated and immersed gold?

The gold-plating process because FPC contains nickel, it is magnetic. When distinguishing whether it is gold-plated or immersed gold, a magnet can be used to attract the FPC board. The attractive is gold-plated, and the unattractive is immersed gold. In addition, the color is also different. Immersion gold is golden yellow. Because the gold surface is large, the gold plating is generally very thin and tends to be white. Of course, there are also thick plating, which is also golden. At this time, it is not easy to distinguish the pads.