What principles should be paid attention to when designing electromagnetic shielding?

(1) Select appropriate shielding effectiveness indicators. The allocation of overall indicators before electromagnetic shielding design is very important. There are 30 dB and 70dB guidelines: Generally speaking, for a pair of devices in the same environment, when the difference between the disturbance level and the sensitivity threshold level is less than 30dB, It is not necessary to carry out special shielding design at the design stage; if the difference between the two exceeds 70 dB, it is difficult to ensure compatibility between the two by shielding alone. Even if the target is reached, the equipment cost will increase sharply. A more feasible way is to make appropriate overall indicators or plans. Adjustment, 30~60 dB is a common expectation for shielding designs.
(2) The structure of the shielding body must be simple, with as few unnecessary holes as possible and no additional gaps as much as possible;
Avoid opening long and narrow holes, and use circular holes as much as possible to discharge them in an array. When there is a conflict between shielding and heat dissipation, try to open as small holes as possible and as many holes as possible, and avoid opening large holes.
(3) There must be no conductors directly passing through the shield. Pay attention to the handling measures of the cable. The handling of the cable is often more important than the shielding itself. Once a cable penetrates the shield, the shielding effectiveness of the shield will be significantly deteriorated.
(4) The electrical continuity of the shield is the most important factor affecting the shielding effectiveness. Relatively speaking, the impact of the shielding performance of the material itself is negligible (with the exception of low-frequency magnetic fields).