In the image shown below, why is the distance marked with "??" not considered for clearance? Is there a slot under that barrier, or does the barrier pass through the PCB?
Clearance is the shortest distance through air between two non insulating conductors.
I am making some assumptions about the image.
- The image is not a full PCB, but rather a section of a PCB. The PCB probably extends furthur but was cut off.
- The darker green colored areas is copper covered with soldermask.
With those assumptions, then the clearance is over the barrier and not around it and more specifically it is from the legs of the IC (since soldermask is an insulator).
IF the traces did extend completely towards the edge of the board, then I would say that the clearance would be around the barrier, since that would be the shortest path through air.