ENIG, which stands for Electroless Nickel/Immersion Gold, when choosing to use the ENIG process for surface treatment of PCB, customers may wonder why nickel plating is needed on the PCB surface. In order to better understand the ENIG process, we can summarize its steps as follows:

The ENIG process comprises two main steps:

Chemical Nickel Plating: Firstly, a thin layer of chemical nickel is uniformly deposited on the exposed copper surface of the entire PCB. This nickel layer not only provides excellent corrosion protection but also has good flatness, suitable for high-density packaging and applications with fine pitch devices.

Gold Plating: Subsequently, a thin layer of gold is deposited on the chemical nickel layer. This gold layer primarily covers the nickel layer, especially in the contact points and connector areas of the circuit board, such as gold fingers. Gold offers excellent oxidation resistance, corrosion resistance, and superior conductivity, ensuring that solder pads maintain good solderability and electrical connectivity for an extended period.

Why ENIG PCB need to plate Nickel?

Protecting the base copper: Nickel plating is employed to safeguard the base copper since copper is prone to oxidation.

Enhancing soldering performance: Nickel exhibits better soldering characteristics than gold and is more stable.

Preventing copper ion migration: If gold is directly plated onto copper, copper ions may migrate to the gold surface, causing streaky oxidation that affects functionality and appearance.