Research On The EMC For The Structural Design Of The Case

The requirement for the reliability of modern electronic equipment has been becoming Higher and higher, especially for EMC. This topic purpose is how to work out the case in which the structure is reasonable and the shielding effectiveness is good. For the working condition of the airborne equipment and the desire for aircraft in GJB151A-1997, make some correlated EMC designs for the airborne case combined with the knowledge about EMC structure design.This article contains two parts:the theory and practice. The EMC design is based on the material choose and the gap, which influence the electromagnetic shielding in case; and how to design the filter on the power line, which influence the EMC design of the case. The paper mainly includes the following aspects:(1)Choose the shielding material:The shielding material is chosen suitable or not directly influence the shielding effectiveness quality. Through analysis the principle of the metal material shielding, we can know the composition of the shielding effectiveness the material, then according to the structure and cost requirements demand of the case, choose the appropriate materials as a shield, and calculated the shielding effectiveness whether meet the requirements or not.(2)The gap of the shield:In the actual project, there are lots of the hole and seam on the shield, which directly affect the integrity of the shielding effectiveness. This paper analysis the shielding effectiveness of the conductive gasket, use the conductive gasket in the hole and seam of the shield, can improve the whole performance of the shield.(3) The power interference:The power wire of the case as a bigger interference source, we can use power filter in the power line and separate shielding to control(4) In order to visualized understanding of the case to the electromagnetic compatibility design, build the entity model of the case by UG, from this model diagram can be easy discover the electromagnetic leakage position and take what kind of measures to solve the problem in production.(5) Reference the electronic equipment shielding requirements and testing methods, this paper test some relevant electromagnetic compatibility, to verify electromagnetic compatibility design of the case is reasonable.