IPC-4556, updated to Revision A in 2025, defines the performance requirements for Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) PCB surface finishes. The standard establishes strict thickness ranges to ensure reliable soldering and wire bonding while mitigating corrosion, with specific focus on tightening control over palladium and gold layers to prevent "black pad". Purchase the full technical standard at IPC Official Store electronics.org
Defines the exact micrometers ( m) or microinches ( ipc4556 pdf
Thick copper is often used to prevent corrosion and act as a final surface finish. The specification requires porosity testing to ensure no pinholes expose the underlying substrate. IPC-4556, updated to Revision A in 2025, defines