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How to Design Half (Castellated) Holes for PCB | PCBasic

At PCBasic, we follow strict manufacturing standards to ensure the accuracy and reliability of half-hole (castellated) designs. Please note the following design requirements, which apply to the copper layer, solder mask layer, and drilling layer:

• The copper layer must retain pads, and the solder mask layer should have corresponding openings.

• Plated through holes that extend beyond the board edge are regarded as half-holes (regular vias are not included).

• The hole diameter should be ≥ 0.4 mm, and the spacing between holes should be ≥ 0.4 mm.

For specific size references, please refer to the chart below and our design examples for correct half-hole layouts.

PCB Thickness (mm)	Minimum Half-Hole Diameter (mm)	Half-Hole Diameter (mm)	Minimum Retained Size After Half-Hole Drilling (mm)
≤ 1.0	0.4	0.4	0.25
1.2 ~ 1.6		0.4 ~ 0.6	0.25
		0.7 ~ 0.9	0.35
		1.0 and above	0.45
2		0.4 ~ 0.6	0.25
		0.7 ~ 0.8	0.35
		0.9 and above	0.45

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