Pdf: Ipc-4556

IPC-4556 references IPC-6012 (Rigid PCBs) and IPC-6013 (Flexible PCBs) for performance classes:

ENEPIG is a multi-layered, surface finish plated over the PCB's copper basis metal. Its structure comprises:

Provides a pristine, non-tarnishing precious metal finish that keeps the surface solderable over long storage periods and acts as an optimal interface for wire bonding. IPC-4556 Thickness Specifications

To understand the strictness of the IPC-4556 standard, one must understand the anatomy of the ENEPIG finish. It consists of three distinct layers deposited sequentially onto the PCB's copper base: ipc-4556 pdf

: 4.5/5

IPC-4556 places strong emphasis on preventing — a brittle, non-solderable nickel layer caused by excessive corrosion of nickel during gold deposition. The standard mandates:

However, specifying ENIG on your fabrication drawing is only the first step. To ensure that your boards meet rigorous quality standards, you need the definitive industry guideline: . It consists of three distinct layers deposited sequentially

: In older ENIG (IPC-4552) finishes, the immersion gold would sometimes attack the underlying nickel, causing brittle "Black Pad" joints that would snap off during use. The Hero (Palladium)

What (e.g., black pad, wire bonding lift) prompted your search?

While you can find blog posts like this one summarizing the specs, when a $500,000 production run is on the line, operating from a free summary is reckless. The official ipc-4556 pdf provides the legal, procedural, and technical rigor required for ISO certification and customer audits. : In older ENIG (IPC-4552) finishes, the immersion

It forms a highly reliable nickel-tin intermetallic compound (IMC) during reflow, which withstands thermal shock and vibration better than many competing finishes.

Demystifying IPC-4556: The Complete Guide to ENEPIG PCB Surface Finishes