While IPC-4556 covers ENIG, it is not always the best choice. Understanding this demonstrates expertise.
IPC-4556 references IPC-6012 (Rigid PCBs) and IPC-6013 (Flexible PCBs) for performance classes: ipc-4556 pdf
ENIG per IPC-4556 is typically required for Class 3 and high-reliability Class 2 applications. While IPC-4556 covers ENIG, it is not always the best choice
The gold layer protects the nickel from oxidation and provides a highly flat, solderable surface. However, too much gold causes embrittlement. ENIG per IPC-4556 is typically required for Class
