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Since creepage distance requirements across a PCB are at least partially due to the potential of conductive pollution, is soldermask a sufficient coating to reduce fully covered traces to pollution degree 1 for determination of required creepage?enter image description here

I'm wondering about the creepage requirements between the heatsink trace and the copper pours on the top and bottom layers under CN4. Since the heatsink trace will be covered with soldermask, as will the copper pours closest to that trace, can I apply the creepage requirements for pollution degree 1, or do the requirements of pollution degree 2 still apply since it's not a conformally coated board?

A.Mac
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    Below it, yes. On top of it, no. Please be aware though that unless IPC 601 class 1, scratches in the soldermask is allowed. In practice, it won’t happen. – winny Jun 08 '20 at 18:21
  • @winny Thanks. I tried to look up IPC 601, and I found IPC-A-600, IPC-A-610, and IPC-6011. They all seem to indicate that Class 1 has the lowest quality requirements while Class 3 has the highest. Your comment implies that Class 1 is the most stringent. Can you clarify? – A.Mac Jun 08 '20 at 18:56
  • Sorry, brain fart. 610 and class 3 yes. – winny Jun 08 '20 at 19:07

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