How to improve radiated emissions when the outer casing of the edge box is insufficiently shielded?

If the plastic casing of the edge box is not treated with conductivity, its shielding effectiveness is almost zero, leading to direct radiation of internal high-frequency signals. The first improvement method is to spray conductive paint or cover the inner wall of the casing with conductive copper foil, requiring a surface resistance of less than 0.1Ω/sq. Conductive foam with a 30% compression should be added at the joint between the upper and lower covers to ensure continuity of conductivity in the gap. Secondly, shielded connectors must be used in the interface area. For example, USB and HDMI metal casings should be connected to the casing ground at a 360° angle via conductive springs. Audiotech recommends using conductive cloth pads, which can achieve a shielding effectiveness of up to 60dB at 1GHz. Simultaneously, internal high-speed lines such as LVDS can use a patch shield CMZ20212A-900T, named CM common-mode Z impedance 20212, size 2.0×2.1mm, 900T impedance 90Ω at 100MHz. Adding ground vias to surround signal vias further improves the performance. After this modification, the radiated emission of the edge box will decrease by 30-1000MHz, with an overall reduction of 15-20dB, successfully meeting EN55032 Class B standards.