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Immersion Gold PCBs

What is Enig PCB?

Enig refers to Electroless Nickel Immersion Gold, is a type of surface plating used for printed circuit boards. ENIG PCBs (also named ENIG PC boards or ENIG circuit board Construction) consists of an underlying layer of nickel with a thin layer of gold over the top. Enig Finish PCB provides various advantages such as high strenght, low contact resistance and etc, so it's widely used in many applications.

The Advantages & Disadvantages of Immersion Gold PCB

Electroless nickel immersion gold is a two layer metallic coating of 2-8 μin Au over 120-240 μin Ni. The Nickel is the barrier to the copper and is the surface to which the components are actually soldered to. The gold protects the nickel during storage and also provides the low contact resistance required for the thin gold deposits. ENIG is now arguably the most used finish in the PCB industry due the growth and implementation of the RoHs regulation.

Enig PCBs• Easy process mechanism
• Flat surfaceh
• Long Shelf Life
• Good oxidation resistance
• High temperature resistance
• Good electric performance
• Good for PTH (Plated Through Holes)
• No Pb
• Good thermal diffusion
• Expensive
• Black Pad / Black Nickel
• Signal Loss (RF)
• Not Re-workable
• Damage from ET
• Complicated Process

The difference Between Immersion Gold and Gold Plating

There are some differences between immersion gold and gold plating as follows:

1. Gold thickness in immersion gold board is more than that in a gold plating board. Immersion gold board is more yellow than a gold-plating board, that’s because gold-plating board has the color of nickel.

2. Compared with gold plate, immersion gold has a denser crystal structure and it is not easy to be oxidized.

3. The immersion gold board has only nickel gold on the pad, so the soldering on the line is more firmly combined with the copper layer. The project does not affect the spacing when making compensation.

4. With the strict requirements for higher precision in PCB fabrication process, line width and spacing have below 0.1mm. Gold-plating board is easier to produce short circuit than immersion gold board.

5. The flatness and service life of immersion gold board is better than the gold plating board.

6. Their crystal structures are different. Comparatively speaking, immersion gold is easier to be soldered with less poor solder issues. Immersion gold board is easier to control the stress, which is benefit for the bonding products. At the same time, immersion gold has a poor anti - abrasion when doing gold finger as immersion gold is more flexible than plating gold.

Besides immersion gold and gold plating, there are more common surface finishes used in PCB manufacturing such as HASL / Lead Free HASL, Immersion Tin, immersion Silver, OSP / Entek and hard gold pcb surface finish.

If you aren't sure what you will need? Consult with a PCB fabricator prior to you making a selection. This will ensure that the combination of the surface finish and material will result in a high-yielding, cost-effective design that will perform as expected.

THE Enig Plating Process

To achieve an ENIG finish on your PCB, there are several steps that you should follow.

Step 1: the surfaces and vias intended for the finish first have a nickel layer applied to the copper in an electroless process as a diffusion barrier.

Step 2: a thin gold finish is applied. The gold adheres to the nickel-plated areas through a molecular exchange, which will protect the nickel until the soldering process.

Check VictoryPCB Immersion Gold PCB manufacturing capabilities in the following table:

Surface FinishContentTechnological Capability
Hot Air Solder Leveling(Include:Lead-Free)Min. panel size155*255mm
Max. panel size600*622mm
Board thickness0.60 - 3.20mm
Solder thicknessStandard: 1- 40um
Advance: 5 - 40um
Minimum spacing form SMT pad0.2mm (with s/m   brigde)
0.25mm (without s/m bridge)
Ground to ground or ground to track Spacing0.20mm
OSPMin. panel size75*75mm
Max. panel size610*610mm
Board thickness0.40 - 3.20mm
Coating thickness0.20 - 0.50um
Immersion gold
(According to IPC-4552-WAM1-2)
Board thickness0.20 - 3.2mm
Nickel thickness3.0-6.0μm
Gold thicknessMin. 0.025um
Immersion Ag
(According to IPC-4553A)
Max panel size406*533mm
Board thickness0.20 - 3.2mm
Immersion Ag thickness0.05 - 0.3um
Immersion Tin
(According to IPC-4554)
Max panel size406*533mm
Board thickness0.20 - 3.2mm
Immersion Tin thickness0.75 - 1.2um

PCB fabrication with ENIG surface finish in VictoryPCB

VictoryPCB is one of the most professional printed circuit board fabrication manufacturers in China. We specialized not only in quick-turn pcb prototype, but also large volume PCB fabrication. We give 100% quality guarantee on printed circuit boards with Enig surface finish.

Get an instant quote for high quality PCBs with any surface finish such as enig finish, enepig surface, HASL, OSP and etc, pls please feel free to contact us with, we will be happy to help you.


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