PCB Surface Treatment Techniques: Immersion Gold vs. Gold Plating

PCB Immersion gold and gold plating are surface treatment techniques used to enhance the durability and performance of printed circuit boards (PCBs). These processes involve applying a thin gold coating to the PCB surface, offering several advantages over traditional finishes.

PCB Immersion Gold Process

The PCB immersion gold process, also known as electroless immersion gold (ENIG), entails the deposition of a thicker layer through a chemical redox reaction method. It is a type of electroless nickel gold deposition that achieves a thicker gold layer. During PCB immersion gold, the board is immersed in a chemical bath containing a complexing agent and a reducing agent. As the PCB moves through the bath, gold ions and the complexing agent undergo a reaction where gold ions (Au3+) are reduced to elemental gold (Au0). This gold adheres uniformly to the PCB surface, forming a continuous gold film.

Advantages of Immersion Gold:

• Thicker thickness compared to electroplated gold
• Surface appears more golden yellow, enhancing customer satisfaction
• Denser crystal structure with improved resistance to oxidation

PCB Gold Plating Process

PCB gold plating, also known as “electroplating gold,” involves dissolving nickel and gold in chemical solutions to deposit nickel gold plating onto the copper foil surface of the circuit board. Electronickel gold plating, known for its high hardness, offers increased wear resistance.

Advantages of Gold Plating:

• Prevents gold wire short circuits during high-precision plating
• Offers superior flatness and longevity compared to traditional gold plating

Application and Considerations

As the wiring of precision products becomes intricate, immersion gold plating prevents short circuits and ensures secure solder mask adhesion. For high-frequency boards, immersion gold plating provides stronger flatness and longevity, eliminating the risk of post-assembly issues.

In conclusion, both immersion gold and gold plating techniques enhance PCB durability and performance, offering benefits such as improved corrosion resistance and excellent solderability. The choice between them depends on specific application requirements and desired finishing characteristics.