Definition

Escape routing is the technique of routing signals from component pads (especially BGAs) to via fanouts or trace channels. For large BGAs, inner rows cannot reach the perimeter directly and must escape through vias to inner layers. Fine-pitch BGAs (<0.8mm) require micro-vias and via-in-pad for escape routing. The number of layers needed depends on BGA pitch, pad count, and via/trace technology. Via-in-pad allows one trace per row per layer to escape. Dog-bone fanout requires space between pads, limiting use at fine pitches.