How to minimize the grounding impedance of HMI (Human Machine Delivery System)?

Minimizing HMI grounding impedance is fundamental to ensuring EMC performance, lightning protection, and personnel safety. First, the system's main grounding terminal should be made of a low-impedance metal material, such as copper or galvanized steel, and reliably connected to the chassis over a large area. The internal PCB ground plane should be as complete and thick as possible, employing a multi-layer design, treating the ground plane as an independent layer, and tightly connecting the surface ground to the inner ground plane through numerous vias to reduce the ground plane's own impedance. All devices requiring grounding, such as filter capacitors, shielding covers, and interfaces, should be grounded nearby through multiple low-inductance vias; the via size and number must meet current and frequency requirements.

Grounding wires or grounding busbars should be short and wide to avoid introducing inductance through thin, long traces. For high-frequency grounding, a grid-like or fully copper-covered ground plane is superior to trace-based methods. Ground connections between modules within the system should use low-impedance paths, such as metal brackets or wide copper foil. Regularly check the tightness of grounding connections to prevent oxidation or loosening that could increase contact resistance. In the design, the low ESL capacitance of Eintraelectronics and its good PCB design practices can be used to jointly build a low impedance grounding system from DC to RF, providing an unobstructed discharge path for interference current, thereby improving the system's immunity and reducing EMI emissions.