What is the role of the gold-immersion process on the surface of printed circuit boards on PCBs?
There is a very common process in the surface treatment of circuit boards, called gold-immersion. The purpose of the gold-immersion process is to deposit a nickel-gold plating with stable color, good brightness, flat plating and good solderability on the surface of the printed circuits on the PCB.
In simple terms, gold-immersion is a chemical deposition method that produces a layer of metal plating on the surface of the circuit board through a chemical oxidation-reduction reaction.
1.The role of gold-immersion process
The copper on the circuit board is mainly red copper. The copper solder joints are easily oxidized in the air, which will cause poor conductivity, that is, poor tinning or poor contact, which reduces the performance of the circuit board. Then, the copper solder joints need to be surface treated. Gold-immersion is to plate gold on it. Gold can effectively block copper metal and air to prevent oxidation. Therefore, gold-immersion is a treatment method for surface anti-oxidation. It is a layer of gold on the surface of copper through a chemical reaction, also called gold.
2.Immersion gold can improve the surface treatment of PCB boards
The advantage of the immersion gold process is that the color deposited on the surface is very stable when printing circuits, the brightness is very good, the coating is very flat, and the solderability is very good. The thickness of the gold in the immersion gold is generally 1-3 Uinch, so the thickness of the gold made by the surface treatment method of immersion gold is generally thicker, so the surface treatment method of immersion gold is widely used in circuit boards such as keypads and gold finger boards, because gold has strong conductivity, good oxidation resistance and long service life.
3.the benefits of using immersion gold circuit boards
- The immersion gold board has bright colors, good color, and good appearance, which improves the attractiveness to customers.
- The crystal structure formed by immersion gold is easier to weld than other surface treatments, and can have better performance and ensure quality.
- Because the immersion gold board only has nickel gold on the pad, it will not affect the signal, because the signal transmission in the skin effect is in the copper layer.
- The metal properties of gold are relatively stable, the crystal structure is denser, and it is not easy to oxidize.
- Since only nickel gold is on the pad of the immersion gold board, the solder mask on the circuit is more firmly combined with the copper layer, and it is not easy to cause micro short circuit.
- The project will not affect the spacing when making compensation, which is convenient for work.
- The stress of the immersion gold board is easier to control, and the experience is better when using it.
4. The difference between immersion gold and gold fingers
To put it bluntly, the gold finger is a brass contact, or a conductor. In detail, because gold has strong oxidation resistance and strong conductivity, the parts connected to the memory slot on the memory stick are plated with gold, and all signals are transmitted through the gold finger. Because the gold finger is composed of many yellow conductive contacts, its surface is plated with gold and the conductive contacts are arranged like fingers, hence the name. In layman’s terms, the gold finger is the connecting part between the memory stick and the memory slot, and all signals are transmitted through the gold finger. The gold finger is composed of many golden conductive contacts. The gold finger is actually a layer of gold coated on the copper clad board through a special process.
Therefore, the simple distinction is that immersion gold is a surface treatment process for circuit boards, while gold fingers are components on circuit boards that have signal connections and conduction. In the actual market, gold fingers may not actually be gold on the surface. Because of the high price of gold, most memory is currently replaced by tin plating. Tin materials have become popular since the 1990s. Currently, the “gold fingers” of motherboards, memory, graphics cards and other devices are almost all made of tin materials. Only the contact points of some high-performance server/workstation accessories will continue to use gold plating, and the price is naturally high.