As its name suggests, conductive rubbers refer to rubberized materials that come with conductive properties and are used for shielding electronic equipment against electromagnetic interference (EMI). These shielding systems feature a conductive gasket, which is positioned between a lid and metal covering. They help attenuate EMI and radio frequency interference (RFI) noise that affect the performance of electronic devices. These electrically conductive rubbers are perfect for applications that need protection from unwanted radiations as well as environmental sealing. They’re used for their resilient and conductive properties in all wireless devices including commercial electronics and sophisticated military equipment. In the shielding industry, different types of conductive rubbers are used. Here we will discuss three major types – conductive elastomer products, Multicon, and Radthin. If you are interested in using conductive rubbers for your next shielding unit, here are a few points you should keep in mind:
Choosing Conductive Rubber
With a shielding efficiency up to 120 dB at 10 GHz, conductive rubber products make excellent EMI shielding products. They also come with exceptional mechanical properties which make them suitable for use in varying operating temperatures.
When choosing these protctive rubber products, you must factor in the aspect of galvanic compatibility. That is because it has a direct bearing on the types of filler and wire you are going to use. You might be wondering what galvanic compatibility means. Well, it is the probability of corrosion between the interface of the metal and the conductive material. While using elastomer materials for a gasket, one of the sides may remain exposed to another metal. In such a situation, you must ensure that the voltage variation between the different metals is the least. To minimize the effects of voltage differences between dissimilar metals, conductive wires and fillers are used.
Every conductive rubber is different from the other with regard to design, features, and EMI effectiveness. So let us talk about a few categories:
Conductive Elastomers: You can die-cut these products to design a flat gasket. Unlike other conductive rubber, it comes with a range of extruded profiles. The common ones include round, P, rectangular, D, and square. Gasket designers shape them as a solid cross-section or concave. Now, this depends on two factors such as the open aperture height and compression for maximum shielding efficiency. Conductive elastomers are made of fluorosilicone, silicone, or ethylene propylene diene monomer (EPDM). You can use specific rubber material depending on its unique properties, which is determined by the application and environment. You can use fluorosilicone for those applications exposed to gasoline, alcohol, and jet fuel. Silicone, on the other hand, is applicable for standard weather sealing and high temperatures of 400 degrees Fahrenheit. Once you select a specific rubber, use conductive metal fillers like silver copper, nickel graphite, aluminum, and silver glass. The choice of the right filler depends on the shielding level needed for a precise application. We recommend that you use a conductive filler to ensure maximum shielding efficiency.
Multicon: It has the perfect blend of conductive wire paths and silicone. The combination offers outstanding environmental sealing together with EMI shielding to frequency levels of up to 6 GHz. Make sure that you use aluminum or monel wires for maximum conductivity. The wires are scattered all through the material width to reduce or eliminate unwanted EMI. You will get multicon in varying widths to comply with shielding requirements of specific devices and applications. Designers can even die-cut the material for meeting different configurations.
Radthin: Though not widely used as multicon or conductive elastomers, this material is ideal for enduring a range of temperature conditions. You can die-cut Radthin into custom shapes and use it in connectors. It consists of a 24-mesh aluminum alloy wire fabric, infused with 50 silicone rubber or durometer neoprene compound. The thickness may be 0.016 or 0.020 inches. It should be noted that silicone Radthin gaskets can withstand a wide temperature range – -65 to 500 degrees Fahrenheit.
Whether you need protection for consumer electronics or defense applications, opt for conductive rubbers and elastomer products to achieve outstanding EMI efficiency. They last longer than any metal shields. They are flexible, can bend easily and enjoy immense resistance to chemicals. No wonder, they are the materials of choice in diverse applications and industries including military, medical, computing, and consumer electronics.