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40 PCB007 MAGAZINE I OCTOBER 2025 A RT I C L E by F ra n k Xu , M a c D e r m i d A l p h a E l e ct ro n i c s S o l u t i o n s The Impact of ENEPIG Specification IPC-4556A: Tighter Controls for ENEPIG Reliability T he demand for higher reliability, performance, and functionality in electronic devices has never been greater, especially in critical markets such as automotive, military and aerospace, and high-performance computing (HPC), where failure is not an option. To meet these rising demands, the 4-14F IPC Standards Committee has released a new revision of the IPC-4556 specification for electro- less nickel/electroless palladium/immersion gold (ENEPIG) finishes. ENEPIG remains a trusted surface finish for its wire bond compatibility, corrosion resistance, and dura- bility through multiple assemblies, but under IPC- 4556A, fabricators now face much tighter process controls. These added requirements present both a challenge and an opportunity: the need to balance stricter compliance with the ability to deliver highly reliable, next-generation electronics. Published in June 2025, revision A was developed in alignment with changes to the ENIG standard (IPC- 4552B) to raise the quality bar for deposit uniformity, corrosion resistance, and measurement capability. For PCB fabricators, this poses a challenge in achiev- ing and consistently delivering the required level of quality. This article will discuss the key changes to IPC- 4556, helping fabricators understand and embrace the challenges posed by the new specification, enabling them to deliver higher-quality ENEPIG deposits.