ENEPIG is a type of surface finish done on copper layer to protect it from oxidation and corrosion in printed circuit boards. This surface finish improves the solderability of copper and is also RoHS compliant.

ENEPIG stands for Electroless Nickel Electroless Palladium Immersion Gold.

Five features that make ENEPIG the best surface finish:

  • For wire bonding applications, the pull strength is of high importance. ENEPIG offers a greater pull strength (aluminum wire: up to 10 gram-force; gold wire: up to 8 gram-force) than soft gold and ENIG (Electroless Nickel Immersion Gold). Hence, becomes the right choice.
  • The multiple electroless deposition of nickel, palladium and gold metals help minimize porosity and protects the cupper layer beneath them.
  • While dealing with high-frequency circuits, nickel might interfere and retard high-frequency signals. With the palladium layer on top of nickel, it can negate the influence of nickel on high-frequency signals.
  • In mixed technology i.e. when RF and digital circuits are involved, opting for direct gold surface finish will lead to assembly related issues. Whereas, ENEPIG is compatible with mixed technology and the various assembly processes.
  • ENEPIG surface finish is the low-cost alternative to direct soft gold plating.

ENEPIG surface finish is ideal for soldering, aluminum wire bonding, and gold wire bonding. This surface finish is formed by the sequential deposition of nickel, followed by palladium, followed by immersion gold. The Nickel acts as a barrier layer and reduces copper dissolution during wave solder, and ensures fine solderability. Nickel also prevents the mixing of copper and solder.

Reasons to Choose ENEPIG Surface Finish

Offers low contact resistance: The electrical resistance is uniform, hence, easier to predict amperage.

Follows RoHS compliance: The palladium completely dissolves into the solder leaving oxide-free nickel surface which allows a reliable tin nickel intermetallic.

Black pads are not an issue with ENEPIG: Black pads are referred to the dark corroded and oxidized Nickel. With ENEPIG surface finish it is no longer an issue.

All the above-mentioned parameters make ENEPIG the most compatible surface finish in the PCB industry. Sierra Circuits offers the option for ENEPIG finish on all of its products.

Sierra Standard Table


Nickel (µ”)

Palladium (µ”)

Plate Gold (µ”)




4 – 8


If the values aren’t specified then our standard table will be considered.


Nickel and Gold Specifications & Standards

IPC Standards

IPC-6012 Rev C

Sierra’s Standard*

Immersion Gold


Immersion Gold – minimum

Coverage and Solderable

1.00 µin min

Electroless Nickel – minimum

118 µin

125-250 µin

Electroless Palladium – minimum

2 µin

4.00 – 8.00 µin

* If a range is not given the number in the Sierra Standards Colum is the minimum.