What is the function of gold dipping process on PCB surface?

What is the function of gold dipping process on PCB surface?
There is a very common process used for surface treatment of PCB boards, which is called gilding The purpose of gold dipping process is to deposit nickel gold coating with stable color, good brightness, smooth coating, and good solderability PCB on the surface of printed circuit In short, gilding is to use chemical deposition to produce a layer of metal coating on the surface of circuit board through chemical oxidation and reduction reaction
1. Function of gold leaching process
Copper on the circuit board is mainly red copper. Copper solder joints are easy to oxidize in the air, which will lead to poor conductivity, that is, tin corrosion or poor contact, thereby reducing the effectiveness of the circuit board. In addition, the copper solder joints need surface treatment. The gold immersed surface is plated with gold, which can effectively block copper metal and air and prevent oxidation. This gold immersion is a surface oxidation resistance treatment method, that is, coating a layer of gold on the copper surface through chemical reaction, also known as chemical gold.
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2. Gold immersion can improve the surface treatment of PCB
The advantages of the gold dipping process are that the color deposited on the surface of the printed circuit is very stable, the brightness is good, the coating is very flat, and the solderability is very good. The thickness of gold leaching is generally 1-3 μ As a result, the gold thickness produced by the gold dipping surface treatment method is generally thick. This gold dipping surface treatment method is widely used in keyboard, gold finger board and other circuit boards. Because gold has strong conductivity, good oxidation resistance and long service life.
3. Advantages of circuit boards with gilded boards
1) Immersion gilt plate is bright in color, good in color and appearance, which improves its attractiveness to customers.
2) The crystal structure formed by gold immersion is easier to weld than other surface treatments, and can have better efficiency and ensure quality.
3) Since the dip plate only has nickel gold on the bonding pad, this will not affect the signal, because the signal in the skin effect is transmitted in the copper layer.
4) The metal property of gold is relatively stable, the crystal structure is more compact, and the oxidation reaction is not easy to occur.
5) Since the gilded plate has only nickel gold on the pad, the bonding between the solder mask and the copper layer on the circuit is stronger, which is not easy to cause micro short circuit.
6) The compensation of this project will not affect the spacing, so it is convenient for construction.
7) The stress of the gilded plate is easier to control, and the use experience is better.
4. The difference between gold dipping and gold finger
The golden finger is more direct This is a brass contact, which can also be said to be a conductor In detail, because the metal fittings have strong oxidation resistance and conductivity, if the parts connected to the memory slot on the memory stick are gold-plated, then all signals are transmitted through the gold finger Because the golden finger is composed of many yellow conductive contacts, its surface is gold-plated, and the conductive contacts are arranged like fingers Generally speaking, the golden finger is the connection between the memory stick and the memory slot. All signals are transmitted through the golden finger The gold finger consists of many gold conductive contacts Gold finger actually covers a layer of gold on the copper clad laminate through a special process Therefore, the simple difference is that gold dipping is the surface treatment process of the circuit board, and gold finger is a component of the circuit board with signal connection and conduction In the real market, gold finger may not be real gold on the surface Because of the high price of gold, most memories are now replaced by tin plating Tin materials have been very popular since the 1990s At present, the "golden finger" of the motherboard, memory, video card and other devices are almost all made of tin According to the data, only some high-performance server/workstation accessory contacts will continue to use gold plating, and the price is naturally very high for PCB boards