How to reduce EMI leakage using vias on a concentrator PCB?

Improperly designed vias on concentrator PCBs can become pathways for high-frequency electromagnetic energy leakage. Key via design considerations to reduce EMI leakage include: controlling via stub length; for high-speed signals, prioritizing blind vias or back-drilling techniques to remove unwanted stubs; for through-layer vias, placing 1-2 grounding vias adjacent to signal vias to provide a path for return current; using teardrop pads at the connection between vias and copper traces; and placing a row of grounding vias as "via fencing" at PCB edges and shielding cavity openings, with a spacing less than λ/20 (e.g., less than 7.5mm for 1GHz). A similar via array should also be used at the power plane edges to form edge coupling with the ground plane. Via sizes should not be too large, typically with an inner diameter of 0.2-0.3mm and an outer diameter of 0.4-0.6mm. Optimizing via design can reduce radiated emissions from the PCB by 5-10dB in the 1GHz band.