I have a 4 layer board with traces and components (mostly SMD) on front and back, and ground and power planes on the inner two layers. I noticed today that on some of my through-hole headers, the copper fills are not respecting zone clearances correctly around the through hole pins. In the same zone, I have a 1x3 header that gets zero clearance from the fill around its pads and a 2x3 that gets the correct zone clearance. I tried adjusting the zone clearance, and with some experimentation I determined that on the 1x3 header, kicad is using the hole as the boundary that it is clearing from, whereas on the 2x3 header it is using the pad. My clearance is set to 0.254mm for this zone, and the 1x3 pad is about that same thickness, which explains why the planes are butted right up against the pad. It makes no sense, though, that it would do that for the 1x3 but then on the 2x3 header it would measure from the edge of the pad. The 2x3 header was added to the board before the zone was created and filled and the 1x3 header was added after. Maybe this has something to do with it??
Has anyone seen this behavior before? To get around this, I had to create a keepout area around the 1x3 header, but I’d rather not do this. Plus, I don’t have confidence the zones are not shorting something else out on the board that I haven’t noticed.
I am running the following:
Version: 4.0.4-stable release build
wxWidgets: Version 3.0.2 (debug,UTF-8,compiler with C++ ABI 1002,GCC 4.2.1,STL containers,compatible with 2.8)
Platform: Mac OS X (Darwin 16.1.0 x86_64), 64 bit, Little endian, wxMac
Boost version: 1.57.0