1. The PCB factory’s circuit board surface treatment processes include: anti-oxidation, tin spraying, lead-free tin spraying, immersion gold, immersion tin, immersion silver, hard gold plating, full board gold plating, gold fingers, and nickel palladium gold OSP, among others.

2. Immersion gold and gold plating are two commonly utilized processes in PCB circuit boards. Many engineers struggle to accurately differentiate between them, so today I will clarify the distinctions.

3. What is gold plating?

Gold plating of the entire board typically refers to “electroplated gold,” “electroplated nickel-gold,” “electrolytic gold,” “electric gold,” and “electric nickel-gold.” It’s important to distinguish between soft gold and hard gold (with hard gold generally used for gold fingers).

4. The process involves dissolving nickel and gold (commonly referred to as gold salt) in a chemical solution. The circuit board is then immersed in the electroplating tank, and when the current is activated, a nickel-gold plating layer is formed on the copper foil surface of the circuit board.

5. Electro-nickel gold is widely favored in electronic products due to its high hardness, abrasion resistance, and resistance to oxidation.

6. What is immersion gold?


Immersion gold is a chemical oxidation-reduction reaction process that creates a layer of plating, typically thicker than other methods. It is a chemical deposition method for nickel-gold layers, allowing for a more substantial gold layer.

**The Differences Between Immersion Gold and Gold Plating**

1. The thickness of immersion gold is generally much greater than that of traditional gold plating. Immersion gold has a more vibrant golden hue, appearing yellower than gilding. Customers often prefer the surface finish of immersion gold due to its distinct appearance. The crystal structures formed by these two methods also differ.

2. Because the crystal structures of immersion gold and gold plating differ, immersion gold is easier to weld compared to gold plating, reducing the risk of poor soldering and subsequent customer complaints. Additionally, immersion gold is softer than gold plating, which is why gold fingers typically utilize gold plating for its durability.

3. The immersion gold board contains only nickel and gold on the pads, ensuring that the skin effect during signal transmission does not interfere with the signal integrity of the copper layer.

4. Immersion gold possesses a denser crystal structure than gold plating, making it less prone to oxidation.

5. As circuit layouts become denser, with line widths and spacing down to 3-4 MIL, gold plating can lead to short circuits due to gold wire. However, immersion gold boards, with only nickel-gold on the pads, prevent this issue.

6. Immersion gold boards feature only nickel and gold on the pads, allowing for a stronger bond between the solder mask and the copper layer. This design helps maintain spacing during any necessary compensation.

7. Immersion gold is typically used for higher-demand applications, offering better flatness. It rarely experiences the black pad phenomenon after assembly, with performance and longevity comparable to gold-plated boards.

8. Given the current high price of gold, many manufacturers are shifting away from producing gold-plated boards, opting instead for immersion gold boards with nickel-gold pads, which are significantly more cost-effective.

1. Immersion gold boards and chemical gold boards are produced through the same process, just as electric gold boards and flash gold boards are. These terms often vary among different sectors of the PCB industry. In mainland China, immersion gold and electric gold are more commonly used, while in Taiwan, they are typically referred to as Huajin and flash gold boards.

2. Immersion gold plates, or chemical gold plates, are often termed chemical nickel gold plates or chemical nickel immersion gold plates. The nickel and gold layers grow through chemical deposition.

3. Gold electroplated plates, or flash gold plates, are commonly known as electroplated nickel gold plates. The nickel and gold layers are developed through DC electroplating.