KiCad layer names for Front (top) copper and Back (bottom) copper.
How it looks
Real geometry: CORE3588 copper, drawn from our board file (2D plan view)
F.Cu, the front (top) copper of CORE3588: 1,961 track pieces, and all 171 parts sit on this side. Ground pour hidden so the tracks show.
Real geometry: CORE3588 copper, drawn from our board file (2D plan view)
B.Cu, the back (bottom) copper, drawn as if seeing through the board from the top: 850 track pieces, used mainly to cross under other wires. Round dots are vias where wires change side.
How it works
Where it fits
These are the outer copper layers. Each becomes its own Gerber file. Vias connect them; the inner layers here are ground planes.