Gold plating and immersion gold for PCBA circuit boards: How to choose the most suitable process?

Gold plating and immersion gold for PCBA circuit boards: How to choose the most suitable process?

Today, a one-stop PCBA smart manufacturing manufacturer will tell you what is the difference between gold plating and immersion gold in the production process of PCBA circuit boards? The difference between gold plating and immersion gold in the production process of PCBA circuit boards. In the PCBA patch processing, the production of PCBA circuit boards is a crucial link. In order to meet different customer needs and application scenarios, circuit boards usually use a variety of surface treatment processes, of which gold plating and immersion gold are two common processes. Although it sounds like these two processes seem similar, they actually have significant differences in many aspects.

The difference between gold plating and immersion gold in the production process of PCBA circuit boards

1. Gold plating process

The gold plating process mainly uses electroplating to evenly attach gold particles to the PCB board. Due to the strong adhesion of the gold plating layer, it is often called "hard gold". For example, our common memory stick gold fingers use this hard gold process because it has the characteristics of high hardness and good wear resistance.

In the gold plating process, it is usually necessary to first plate a layer of nickel and then a layer of gold. Such a metal layer structure is copper-nickel-gold. In addition to enhancing the adhesion of the gold layer, the nickel layer also plays a certain role in electromagnetic shielding because nickel is magnetic.

However, a potential problem with the gold plating process is that since it is carried out before solder mask, sometimes the green oil may not be cleaned cleanly, which may affect the subsequent welding and tinning process.

2. Immersion gold process

The immersion gold process generates a layer of gold plating on the pad of the PCB board through a chemical oxidation-reduction reaction. Since the adhesion of this gold plating is relatively weak, it is often called "soft gold".

Unlike the gold plating process, the immersion gold process is carried out after solder mask. Therefore, it is not easily affected by the unclean green oil cleaning, making it easier to achieve good welding and tinning effects. In addition, the immersion gold process directly immerses gold on the copper skin, and the metal layer structure is copper-gold, without a nickel layer, so it does not have a magnetic shielding effect.

From the perspective of crystal structure, immersion gold is easier to weld than gold plating, because the crystal structure of immersion gold is denser and less prone to oxidation, thereby reducing the risk of poor welding. In addition, the flatness of the circuit board after immersion gold is usually better, which is an important advantage for boards with higher requirements.

In summary, gold plating and immersion gold each have their own characteristics and application scenarios in PCBA circuit board production. The gold plating process has advantages in situations where wear resistance and electromagnetic shielding are required due to its high adhesion and electromagnetic shielding characteristics; while the immersion gold process is favored in patch processing with higher requirements due to its good welding performance, flatness and non-oxidation characteristics. When choosing which process to use, it is necessary to comprehensively consider the specific product requirements and application scenarios.