"All exposed copper pads shall have ENIG per IPC-4556A: Ni 3-6µ, Au 0.05-0.23µ, P% 7-11."
. Often referred to as the "universal surface finish," ENEPIG is favored for its versatility across soldering, wire bonding, and contact applications. Core Requirements and Specifications ipc4556 pdf
IPC-4556 defines the industry standard for Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) plating, providing requirements for thickness ranges to ensure optimal shelf life and wire bondability on PCBs. The specification establishes specific ranges for nickel, palladium, and gold layers to mitigate corrosion while supporting lead-free solder assembly. For detailed technical specifications, review the paper from Uyemura . Conforming to IPC-4556 with XRF | ENEPIG Surface Finish "All exposed copper pads shall have ENIG per
The IPC-4556 PDF document is a valuable resource for: ipc4556 pdf