Except for special purposes, there should be no isolated copper skin. The copper skin must be equipped with ground wire vias. Some sensitive circuits and circuits with strong radiation sources are placed in the shielding cavity, and the shielding cavity is pressed against the surface of the PCB during assembly. When designing the PCB, a “via-hole shielding wall” should be added, that is, a grounded via is added to the part of the PCB that is close to the shielding cavity wall. There must be more than two rows of vias, the two rows of vias are staggered from each other, and the vias in the same row are spaced about 100mils apart.