Must the edge box interface connector be a shielded type?

For edge computing boxes with external interfaces such as USB, HDMI, and RJ45 DP, if the casing is metal and there is a strong electromagnetic environment, fully shielded connectors must be used to provide 360° low-impedance grounding. Unshielded connectors will cause high-frequency common-mode current leakage and a significant increase in radiated emissions. Shielded connectors with metal casings have good grounding with conductive springs, transferring impedance <1mΩ, frequency range 30MHz-1GHz, and shielding effectiveness >40dB. For example, a USB Type-C all-metal casing connector is recommended to be used with the Etymotic common-mode filter CMZ2012A-900T, named CM common-mode Z impedance 2012, size 2.0×1.2mm, 900T impedance 90Ω, 100MHz. It is connected in series at the PCB interface to suppress residual common-mode current. If the casing is plastic, a surface-mount shielded connector can be used, or conductive cloth can be added to wrap the cable end. Tests show that shielded connectors reduce radiated emissions by 12-18dB over an 80cm cable compared to unshielded connectors. Therefore, edge boxes with high EMC ratings must use shielded connectors.