A comparison of relative shielding provided by stitching vias and edge plating

Adding stitching vias around the perimeter of a printed circuit board (PCB) is a commonly used technique to reduce electromagnetic interference (EMI) from PCB structures. As system operating frequencies increase along with higher density and higher power utilization, there is a tendency to reduce the spacing between stitching vias in order to provide more shielding at the edge of the PCB. Plating the edge of a PCB provides continuous shielding with one exception. This exception is in the vicinity of the break-off tabs located around the edge of the PCB. In this area, a gap is required in the plating to accommodate this tab. Localized stitching vias may be incorporated adjacent to this gap. This paper compares the relative shielding provided by PCB stitching vias and PCB edge plating up to 40 GHz.