Gold Plating: Gold plating is a process where a thin layer of gold is deposited onto the surface of another metal using electroplating. The gold particles are firmly attached to the PCB, which provides strong adhesion, also known as hard gold. The gold fingers on memory modules are made of hard gold, offering increased durability and resistance to abrasion.
Immersion Gold: Immersion gold is a method where a chemical reaction causes gold particles to adhere to the PCB surface. This process results in weak adhesion, often referred to as soft gold.
Why Use Gold Plating?
As integrated circuits (ICs) become more compact and their pins become denser, this increases the difficulty of surface-mount technology (SMT) placement. Additionally, the shelf life of HASL (Hot Air Solder Leveling) boards is short. Gold plating addresses these issues by offering a more durable and longer-lasting alternative:
However, as circuit lines become denser, there is an increased risk of short circuits. Additionally, higher signal frequencies exacerbate the skin effect, which can degrade signal quality.
Skin Effect: At high frequencies, alternating current tends to concentrate on the surface of the wire, leading to increased resistance and potential signal loss.
Why Use Immersion Gold?
To overcome the limitations of gold plating, immersion gold technology offers the following advantages:
- Due to differences in crystal structure between immersion gold and gold plating, immersion gold is easier to solder and less likely to cause soldering issues. It also allows for better stress control during manufacturing.
- Only the pads are coated with nickel-gold, ensuring that signal transmission within the copper layer remains unaffected by the skin effect, preserving signal integrity.
- Immersion gold is less prone to oxidation, providing a more reliable surface for long-term use.
If you have any questions about PCBs or PCBA, please feel free to contact me at info@wellcircuits.com.
