I just got back 4 prototype boards for my 80486 S100 board. Spent many days with KiCAD laying it out etc. When I got the boards back (from PCBCart), to my horror I noticed that the back pins of the 80486 socket did not have solder pads. The front pins were fine. I have to lay out a custom footprint for the 80486 chip in KiCAD but unfortunately I did not add the solder mask requirement on the back of the chips footprint. I had it on the front but not the back. Just wanted to let people know so it doesn’t happen to you! Hhave to redo the boards again!