Work out ball grid array pitch instantly with clear inputs, formula shown and shareable results.
A BGA's array span is (grid - 1) times the pitch, and the space between adjacent balls determines how many traces can escape each channel. A 1 mm pitch with 0.5 mm balls leaves 0.5 mm, enough for two 100 micron traces with clearance — which is what sets the PCB layer count.
BGA geometry
grid = ceil(sqrt(balls)); span = (grid - 1) x pitch; escape channels = (pitch - ball diameter) / (trace + gap)
Fewer escape channels per row means more layers are needed to route out all the signals, and finer pitch forces microvias and via-in-pad.
A short trace from the ball pad to a through-via just outside it. It works down to about 0.8 mm pitch; below that via-in-pad becomes necessary.