IPC-4556

Specification for Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) Plating

This specification sets the requirements for the use of Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) as a surface finish for printed boards. ENEPIG is a tertiary layered surface finish plated over copper as the basis metal.

ENEPIG is a multifunctional surface finish, applicable to soldering and to gold, aluminum and copper wire bonding. It is also suitable as the mating surface for soft membrane and steel dome contacts. The electroless palladium layer forms a diffusion barrier that impedes nickel diffusion to the gold surface and, in turn, the immersion gold protects the palladium layer from reacting with contaminants prior to processing that might otherwise affect joining processes, such as wire bonding and soldering.

Recommended Drawing Call-Out

  • Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) final finish per IPC-4556
  • Electroless Nickel 118 - 236 µ"
  • Electroless Palladium 2 - 12 µ" *Immersion Gold minimum 1.2 µ"
  • Immersion Gold minimum 1.2 µ"

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