PCB connectors are typically located on the edge of a board to avoid physical contact of cables and wires with other components and to minimize trace lengths by having signal input/output (I/O) ports close to the components that use them.
Although it can be advantageous for the signal quality to place PCB connectors on or near the edge of the board, it can cause major difficulties for manufacturing.
The biggest issue is how to best panellise, depanellise and manage the boards during the PCB manufacturing and Assembly process.
We use 2 mm breakrouting between the panel border and the PCB which leaves enough space for a component like a common micro USB, but larger parts may need some extra room.
If you select a component for your design and you place it close to the PCB edge, consider its size, weight and any protrusion it might have and do not place them over a break routing tab of the panel. The operation of separating the panel may become impossible or it can weaken the component’s solder joints, or even pop it off the board completely.
If Eurocircuits builds the panels for assembling the boards, we will avoid these issues be default.
We advise not to use components that need the panel border for support and that need depth routing of the panel border in order for the component to lie flat after placement. Typically these are overhanging connectors with Z-axis protrusion outside the PCB border.