PCB Immersion Gold vs Electroplated Gold

The differences between PCB immersion gold and electroplated gold mainly lie in process principles, appearance, thickness, soldering performance, oxidation resistance, and signal transmission performance.

1. Process Principle

• Immersion Gold: A chemical displacement reaction is used to deposit a thin layer of gold on the copper surface of the PCB. The gold salt solution (e.g., potassium gold cyanide) reacts with copper, reducing gold ions to gold atoms that are then deposited on the copper surface.

• Electroplated Gold: Gold is plated onto the PCB surface through an electrolysis process. In an electrolytic cell, the PCB serves as the cathode, gold as the anode, and gold ions in the electrolyte are reduced at the cathode, depositing a layer of gold on the PCB surface.

2. Appearance and Thickness

• Immersion Gold: The gold layer is relatively thin, typically ranging from 0.025 to 0.1 μm. The appearance is golden yellow, with a more yellowish hue.

• Electroplated Gold: The gold layer is thicker, usually between 0.1 and 2.5 μm, and has a lighter color.

3. Soldering Performance

• Immersion Gold: Offers better soldering performance and reduces the likelihood of soldering defects.

• Electroplated Gold: Has relatively poorer soldering performance and may cause soldering defects.

4. Oxidation Resistance and Corrosion Resistance

• Immersion Gold: The gold layer is uniformly deposited through chemical plating, resulting in a denser crystal structure with superior oxidation and corrosion resistance.

• Electroplated Gold: Has relatively weaker oxidation resistance.

5. Signal Transmission Performance

• Immersion Gold: Results in lower signal loss and minimal impact on signal integrity, making it suitable for high-frequency and high-speed circuits.

• Electroplated Gold: May have a certain impact on signal transmission.