Introduction to EMI Materials

Most businesses these days will need to protect against electromagnetic interference (EMI). Protection against EMI is known as EMI shielding. EMI shielding comes in many different forms. One common tool used for EMI shielding is an EMI gasket. There are many facets to gaskets. Before purchasing an EMI gasket familiarize yourself with the common materials.

Conductive elastomers work with commercial and military applications.  This material is filled with a duo of metals including nickel and aluminum; silver and aluminum; silver and copper; nickel and graphite; and silver and glass. The binder for this type of material is either fluorosilicone or silicone.  

The conductive elastomer gaskets will fit into one of two categories: molded only or extruded only.

Many conductive elastomer gaskets are available with lightning strike resistance. The particular flange design will determine if the material will be resistant to a lightning strike. Tests have shown that gasket material can withstand beyond five kA/in. Ask the manufacturer to provide you with more information regarding lightning strike resistance.

Each particular material will have a different type of resistance to fluid exposure. Consider the fluid type you will be working with before making a purchase on EMI materials. Silicone is ideal if you are working with high and low temperatures. It does not operate well with hydraulic fluids, hydrocarbon fuels, and STB. Fluorosilicone also works well with low temperatures. It works with high temperatures but not as well as silicone. Fluorosilicone works well with most fluids, but it is not recommended for hydraulic fluids use.

Related Reading

• The Science of Shielding
• Shielding Gaskets and Corrosion
• Selection of Seal Cross Section
• Integrated Circuits Have Problems with EMI
• RFI and EMI: Frequent Questions