How to reduce EMI leakage in EPS vias?

Improperly designed vias on EPSPCBs can become "antennas" for high-frequency EMI leakage. Key design considerations to reduce leakage include:

1. Controlling the number of vias on critical paths: Minimize the use of vias on critical high-frequency paths (such as switching nodes and clock lines). When necessary, prioritize blind or buried vias to reduce via stubs.

2. Increasing return vias: Place one or more ground vias adjacent to each signal via, especially high-speed signal and power vias, to provide the shortest path for high-frequency return current and create local shielding.

3. Via array shielding: Arrange dense arrays of ground vias around or along the board edge of strong noise sources (such as crystal oscillators and switching ICs) to create a "Faraday cage" effect, confining noise within the board.

4. Avoiding sensitive layer crossings: Avoid having unrelated vias crossing the reference plane directly below sensitive circuit areas, causing planar interruptions or coupling.

5. Filling and plugging vias: Filling and plugging critical vias with conductive material can improve EMI, heat dissipation, and reliability.