How to suppress EMI in vias and gaps of intelligent controller PAC?

Suppressing EMI caused by vias and chassis gaps in the PAC PCB of the intelligent controller requires addressing both structural and material aspects. For vias, avoid using redundant vias near high-speed signal lines; use blind or buried vias when necessary. Employ anti-pad design between vias and the reference plane, with a diameter 0.5mm larger than the via pad to reduce parasitic capacitance. Add grounding vias (0.3mm diameter) in densely populated via areas to provide shielding. For chassis gaps, ensure smooth mating surfaces and fill them with EMI conductive pads (such as beryllium copper springs or conductive foam), with pad compression controlled between 30% and 70%. Use waveguides for ventilation holes (aperture diameter less than λ/20, e.g., less than 15mm at 1GHz). Use transparent conductive film (ITO) or metal mesh for the display window. After optimization, the via transfer impedance at 1GHz is less than 0.1Ω, and the chassis gap shielding effectiveness is greater than 40dB, meeting the IEC61000-5-7 chassis shielding effectiveness test requirements.