A common method for EMI mitigation in PCB design is the use of through-hole stitching and shielding vias. Stitching refers to using a general pattern of ground vias scattered across the entire board. Spacing between each via can vary based on the needs of the design. These vias connect, or staple, the ground planes of the PCB together, creating an overall strong ground for the circuit. The additional grounds also serve to further surround the power plane or traces, aiding in field containment (Figure 3-10). Having a strong ground in the circuit is one of the most effective ways of reducing EMI.

The best practice is to place an additional ground via at connection points (Figure 3-11). Connection points are anywhere a trace is connecting to another element, such as a via or passive. The extra via allows for a shorter path to ground, reducing inductance and EMI.

Shielding, like stitching, also utilizes ground vias. However, instead of being scattered throughout the entirety of the board, shielding vias are placed alongside the signal traces (Figure 3-12). These vias are able to assist in filtering out certain frequencies. Space the array of vias 1/20th of the wavelength for lower clocking frequencies or 1/10th of the wavelength for higher frequencies. While this method prioritizes striplining specific traces, using through-hole vias can have a similar effect to using stitching vias, strengthening the overall ground and striplining parts of the power plane.