Electrical safety spacing:
- Spacing between wires:
According to the production capacity of PCB manufacturers, the spacing between traces shall not be less than 4MIL. Line spacing is also the spacing between line to line and line to pad. So, from our production perspective, of course, the larger the better if conditions permit. Generally, the conventional 10MIL is more common.
- Pad aperture and pad width:
According to PCB manufacturers, the pad aperture shall not be less than 0.2mm if mechanical drilling is used, and shall not be less than 4mil if laser drilling is used. The aperture tolerance varies slightly depending on the board material. It can generally be controlled within 0.05mm. The pad width shall not be less than 0.2mm.
- Spacing between pads:
According to the processing capacity of PCB manufacturers, the spacing between pads shall not be less than 0.2MM.
- Spacing between copper and board edge:
The spacing between live copper and PCB board edge should be no less than 0.3mm. If copper is laid over a large area, it is usually necessary to have an inward distance from the board edge, which is generally set to 20mil. Generally, for mechanical considerations of the finished PCB or to avoid curling or electrical short circuits caused by copper exposed at the board edge, engineers often inward large copper blocks by 20mil relative to the board edge, rather than laying copper all the way to the board edge. There are many ways to deal with this copper shrinkage. For example, draw a keepout layer at the board edge, and then set the distance between the copper and the keepout.