IPC-4556 establishes industry standards for Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) surface finishes, providing requirements for thickness and performance to ensure reliability in soldering and wire bonding. The specification enables superior surface planarity for fine-pitch components while mitigating risks associated with black pad or nickel diffusion. For a deep dive into the technical data and "Round Robin" study results that formed these standards, you can find the official IPC-4556 PDF on the IPC (Global Electronics Association) website. Conforming to IPC-4556 with XRF | ENEPIG Surface Finish
). This protective layer prevents the nickel from oxidizing and helps mitigate the "Black Pad" defect seen in older ENIG finishes. Gold (Au): ipc-4556 pdf
According to IPC-4556 guidelines , the plating must meet strict thickness ranges to ensure reliability: Nickel (Ni): 3.0 to 6.0 μm (118.1 to 236.2 μin) Palladium (Pd): 0.05 to 0.15 μm (2.0 to 12.0 μin) Conforming to IPC-4556 with XRF | ENEPIG Surface Finish )