How can the grounding impedance of a power FTU be minimized?

Minimizing grounding impedance improves interference discharge efficiency. A multi-layer parallel and short-path design is employed. The chassis grounding uses a 25mm² copper strip, less than 0.5m in length, with a DC resistance of less than 0.5mΩ. The internal grounding wire uses a star topology, with a wire diameter of 2.5mm² and a length of less than 100mm. The PCB grounding layer uses 2oz thick copper, connected through multiple vias with a via spacing of less than 5mm. The grounding point uses metal screws with star washers, achieving a contact pressure greater than 5N·m. High-frequency grounding uses a PBZ1608E600Z0T ferrite bead connected in parallel with a 0.1μF capacitor to provide a low-impedance path. With this design, the grounding impedance is less than 0.1Ω in the DC-100MHz band, and the electrostatic discharge time is less than 1ns, meeting the IEC 61000-4-2 fast discharge test requirements.