half holes plated

Plated Half-Holes, also referred to Castellated Holes, are rows of holes are drilled alongside the boundaries of a rigid printed circuit board (PCB), then to be through plated and milled off half. You may have seen some Wi-fi modules which then soldered onto a larger PCB similar to the way in which ICs are mounted. Plated half-holes are mainly used for board-on-board connections, mostly where two PCB boards with different technologies are soldered together.