How to reduce the high-frequency grounding impedance of a smart controller PAC?

Reducing the high-frequency components of the PAC's grounding impedance is crucial for suppressing radiation and improving immunity. Measures include: using large-area copper foil or a flat metal plane as the grounding layer with a thickness of at least 2 oz (70 μm); connecting the grounding layer to the chassis at multiple points using metal screws with star washers, with screw spacing less than λ/20; using wide, short, flat braided grounding wires with an aspect ratio less than 3:1 to reduce inductance; increasing the number of grounding vias on the PCB (e.g., at least 4 vias per square centimeter), with a via diameter greater than 0.3 mm; for critical grounding points, multiple capacitors (e.g., 0.1 μF, 0.01 μF) can be connected in parallel to provide a high-frequency grounding path; using an impedance analyzer, the optimized grounding impedance should be less than 0.1 Ω at 100 MHz; reducing the high-frequency grounding impedance can reduce the PAC's radiated emissions by 10 dB in the 30 MHz-1 GHz band and pass the IEC61000-4-3 radiated immunity test.