What is PCB sinking gold, gold plating. What is their difference?

What is PCB sinking gold, gold plating. What is their difference?

What is Immersion Gold, Gold Plated

Immersion gold uses a chemical deposition method, which generates a layer of plating through a chemical oxidation-reduction reaction, which is usually thick. The gold layer deposition method is a kind of chemical nickel gold, which can reach a thicker gold layer.

Gold plating uses the principle of electrolysis, also known as electroplating. Most other metal surface treatments also use electroplating. It is to deposit a thin layer of gold on the surface of another metal by electroplating. Moreover, due to the strong adhesion of gold plating, gold particles are mainly attached to the circuit board, so it is also called hard gold.


Immersion gold application range

Immersion gold process in PCB assembly

It is mainly used for high-demand sheet products, and has better requirements for flatness. Generally, heavy gold is used. After assembly, the heavy gold generally does not look like a black pad. The flatness and service life of the immersion gold plate are better than that of the gold plate.

The stress of the immersion gold plate is easier to control, and for the bonded products, it is more conducive to the bonding process.

As high-speed printed circuit boards have higher and higher processing accuracy requirements, the line width and spacing have reached below 0.1mm. Gold plating is easy to short-circuit the gold wire. There is only nickel and gold on the pads of the immersion gold board, so it is not easy to short-circuit the gold wires.

In the actual product application, 90% of the gold plate is immersion gold plate, because the poor weldability of the gold plate is his fatal flaw, and it is also the direct reason that many companies abandon the gold plating process! Therefore, most factories currently use the immersion gold process to produce gold plates. However, The gold plating process is more expensive than the immersion gold process (higher gold content).


Application range of gold plating

Gold plating process in PCB assembly

The gold-plated electroplating layer has good corrosion resistance, conductivity and high temperature resistance, and is widely used in fine instruments, printed circuit boards, integrated electrical appliances, electronic tubes, electrical contacts and other parts that require long-term stability of electrical parameters. In addition, the plating of some fashion jewelry wholesale, wall clock parts, artwork, etc. also account for a considerable proportion.

In industrial production, in order to reduce the cost of parts and save production costs, the decorative effects of the gold-plated electroplating layer, such as brightness, leveling, etc., are usually plated with one or more bottom layers before gold plating, as the gold-plated layer The bottom layer is bright nickel layer.


The difference between immersion gold and gold plating

1.The gold thickness of the gold plate is usually greater than the gold thickness of the immersion gold plate. The color immersion gold board is more yellow than the gold-plated board because the gold-plated board has the color of nickel. To

2. Their crystal structures are different. In contrast, immersion gold is easier to solder and has fewer soldering problems. Immersion gold plate is easier to control stress, which is beneficial for bonding products. At the same time, immersion gold has poor abrasion resistance when making gold fingers, because immersion gold is more flexible than electroplating gold.

3. Nickel is only used for the underlayer of the immersion gold plate, so the signal transmission in the skin effect will not affect the signal of the copper layer. 

4. The crystal structure of immersion gold is much denser than that of gold-plated plate, so it is not easy to oxidize. 

5. For high-demand boards, the flatness requirements are better, and generally use immersion gold, and immersion gold generally does not appear black pad phenomenon after assembly. Immersion gold plate has better flatness and service life than gold plate.