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Below are two pictures.

The first picture is from IPC-2221. I made the second picture.

Which categories do the L1, L2, L3 and L4 clearances in the second picture belong to in the first picture at 310 volts?

I'm not sure, I produce different meanings.

  • L1?
  • L2?
  • L3?
  • L4?

enter image description here

enter image description here

JRE
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johny adv
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  • While I don't feel qualified to answer, I would really like to know why this is voted to be closed ?! It is a precise question, no? – tobalt Oct 23 '21 at 10:52
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    my guess is L1 and L2 are B4, the other two are B2/3 depending on elevation – tobalt Oct 23 '21 at 10:56
  • It may be a precise question but, it also contains the clear answers within itself. However, if the OP were to ask if solder-resist is regarded as a conformal coating or, as a permanent polymer coating, then that would be a decent question @tobalt but, given that the same distances apply to the voltages mentioned, then it's still a "non-question". – Andy aka Oct 23 '21 at 13:02

1 Answers1

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This question is a follow-on from this question

Not shown in your diagram is the extents of your solder mask which is the coated portion of your PCB.

If you read paragraph 6.3.4 (clarifying B4), PCB copper areas that have solder mask coating fall under B4. However, the exposed (uncoated) pads and traces on the PCB fall under B2 (B3 for altitude > 3050m).

Uncoated (no conformal coating) component leads fall under A6.

IPC-2221 is a best practices guide. You can disregard the numbers and make the clearances smaller, but reliability will be compromised - perhaps to zero.

qrk
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