The method of using the electromagnetic sealing gaskets has a great influence on the shielding effectiveness of the shielding body.
1) Among all kinds of electromagnetic sealing gaskets, the finger reeds allow sliding contact, and other types of gaskets must not allow sliding contact, otherwise the gasket will be damaged.
2) Some types of gaskets will be irreversibly damaged by excessive compression, so a pressure limiting structure should be installed to ensure a certain amount of compression during use.
3) Except for the conductive rubber gasket, when the electrical contact between the gasket and the body of the shielding body is good, the shielding effectiveness of the gasket has no positive relationship with the compression amount, and increasing the compression amount does not improve the shielding effectiveness. The shielding effectiveness of conductive rubber increases with the increase of compression, which is related to the increase of the density of conductive particles in conductive rubber.
4) The metal plate in contact with the gasket must have sufficient rigidity, otherwise it will be deformed under the elastic force of the gasket and form new discontinuous points, resulting in radio frequency leakage. For frontal compression structures, proper spacing of fastening screws can prevent panel deformation.
5) When the size permits, try to use thicker pads, which can allow greater processing errors for metal structural parts, thereby reducing costs. In addition, thicker pads are generally softer and require less rigidity of the metal plate (thereby avoiding radio frequency leakage caused by deformation of the structure due to insufficient rigidity).
6) The gasket material should be installed in a position that is not easy to be damaged. For example, for a large screen door, the liner should be installed in the door frame and provide some protection; for a detachable panel, it is better to install the liner on the movable panel, so that it is easy to store when the panel is removed.
7) The metal surface on which the electromagnetic sealing gaskets are installed must be clean and conductive to ensure reliable conductivity.
8) Try to use the groove installation method. The function of the groove is to fix the gasket and limit excessive compression. When the slot installation method is used, the contact between the two parts of the shield not only realizes complete contact through the gasket, but also has direct contact between the metals, so it has the highest shielding effectiveness.
9) The shape of the installation groove has two types: straight groove and dovetail groove. The straight groove is easy to process, but the gasket is easy to fall out. Dovetails do not have this problem. The height of the groove is generally about 75% of the pad height (for specific dimensions, refer to the compression amount required by the pad manufacturer), and the width must ensure that there is enough space to allow the pad to stretch when it is compressed. When the electromagnetic sealing gaskets is installed in the straight groove, the gasket needs to be fixed.
Generally, it is recommended to use conductive adhesive for bonding in the design data, but this has two disadvantages: one is that it will increase the cost, and the other is that the conductive adhesive will age and cause the shielding performance to decrease. Here it is recommended to use a non-conductive glue and apply a small drop where the fastening screw goes through. In this way, although the adhesive place is not conductive, the metal screw plays the role of conductive contact, and the shielding effect is relatively stable.
10) Direction of sliding contact, only finger reeds allow sliding contact. When installing the reed, pay attention to the orientation of the reed so that the compressive force applied by the sliding will allow the reed to extend freely. Under normal circumstances, the reed can be glued to the back, but attention should be paid to the curing time (refer to the instructions of the reed manufacturer). In harsher environments (too high or too low temperature, excessive mechanical force, etc.), the clamping structure can be used.
11) Select the appropriate electromagnetic sealing gaskets material according to the base material of the shielding body to make the contact surface reach the state of electro-chemical compatibility. For related design, please refer to the information given later. If the space permits, use an environmental sealing gasket at the gap between the gasket and the gasket, and make the environmental sealing gasket face the external environment to prevent the electrolyte from entering the joint surface where the conductive gasket and the shield are in contact.
12) The position of the screw, generally, it is not very important to install the screw on the inside or outside of the precipitation, but in the case of high shielding requirements, the screw should be installed on the outside of the liner, in order to prevent the screw from penetrating the shielding box, resulting in additional of leaks.