I'm developing a printed circuit board, and considering I have some traces with 220Vac I'm worried about the clearance.

After research, I conclude that these are the requirements that I need to fulfill:

Voltage (peak) = 350V, according to IPC-2221B:

  • External Trace -> 2,5 mm
  • Internal Trace -> 0,25 mm
  • Coated Trace -> 0,8 mm

The application is for normal conditions, 25°C Ambient Temperature.

In the manufactured boards, like the below, can I consider the traces coated?

(source: pcbway.com)


Yes, soldermask counts as a "coating". You still need to take note, however, of the spacing between exposed pads that are connected to those traces. The IPC required spacing for exposed pads will be different from that of "coated" traces.

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