Many designers mistakenly assume that any thick copper plating will suffice. However, without adherence to IPC-4556, you risk:

If you manage to access the official document (or a reference guide based on it), here are the critical sections you should focus on:

Generally 4–10 µin (0.1–0.25 µm). This "middle" layer is critical; it must be thick enough to impede nickel diffusion to the gold surface, preventing the "black pad" or hyper-corrosion issues common in standard ENIG finishes.

Ipc4556 Pdf Official

Many designers mistakenly assume that any thick copper plating will suffice. However, without adherence to IPC-4556, you risk:

If you manage to access the official document (or a reference guide based on it), here are the critical sections you should focus on: ipc4556 pdf

Generally 4–10 µin (0.1–0.25 µm). This "middle" layer is critical; it must be thick enough to impede nickel diffusion to the gold surface, preventing the "black pad" or hyper-corrosion issues common in standard ENIG finishes. Many designers mistakenly assume that any thick copper