How To Correctly Select EMI Shielding Materials

With the increasing number of electronic devices, EMI problems are becoming more and more serious, and EMI shielding materials have risen and are widely used in various fields. When selecting the most effective EMI shielding materials on commercial electronic devices such as communications, computers, automation, medical, etc., the following types can generally be considered: beryllium copper reeds, conductive foam, conductive rubber, etc. According to the different needs of the equipment, different shielding materials can provide different degrees of electromagnetic shielding, suitable for different shapes and environmental sealing requirements.
When designing and selecting EMI shielding materials, the following five factors should be considered:
1. Shielding performance, most commercial equipment requires attenuation of 60~120dB;
2. Compression amount, most commercial equipment consider low closing force design, the compression amount has a great impact on the shielding efficiency of conductive rubber, while the compression amount has little effect on the shielding efficiency of metal reeds and conductive foam;
3. Shielding material shape; mechanical durability; Sealing of external environment such as water and dust;
4. Electrocorrosive between shielding material and contact metal medium to avoid the generation of current that causes electrical erosion;
5. Cost, service life, tolerance and installation method (riveted type, bonded type, etc.)
The following are the three EMI materials:
1. Metal reeds
Beryllium copper reeds are finger-shaped copper reeds made of special alloy beryllium copper, which combine high-grade EMI shielding effect and elastic hook and jaw rub with small sealing force characteristics, making it the best choice when mechanical durability is required. The high performance parameters of beryllium copper shrapnel: high tensile strength, good corrosion resistance and good electrical conductivity, make it an ideal EMI shielding material for use in a wide frequency band, and can be used in a wide range of electronic devices with EMI/RFI or ESD problems. There are different finished products of bright copper, bright nickel and bright tin, which are installed on different metal surfaces to reduce galvanic noise and galvanic corrosion between different metals. Spira metal spiral tubes can be trough mounted or filled with rubber or silicone cores.