What Materials Are Used for Electromagnetic Shielding?

What Materials Are Used for Electromagnetic (EMI) Shielding? It focuses on using metallic foil, cable braid, or a Faraday cage arrangement to protect electronic components. Typically, technicians wrap wire bundles in metallic foil, plaited braid, or a metal box over the sensitive parts. Audio speakers also contain an inner metallic casing to block EMI caused by the common elements near the speakers.

Copper

Copper is a highly conductive metal, making it an effective RF and emf shielding material. In addition, unlike other metals, copper is not easily corroded, is durable, and resists oxidation. As a result, copper is the most effective EMI and RF shielding material available. However, copper is not the only metal used for electromagnetic shielding. Nickel and copper alloy 770, or C-70, are two alternatives to copper. These alloys resist oxidation and corrosion and can be used for shielding applications in the mid-kilohertz to gigahertz range.

Carbon steel is another common material for EMI shielding. Its non-ferrous properties, high conductivity, and relatively low weight make it a popular choice. However, the downside of carbon steel is that it is expensive and prone to corrosion. One way to combat this is to use galvanized steel with a protective coating on the surface. Aluminum is another option but is less effective than steel for shielding low-frequency electromagnetic waves.

Aluminum

One of the most prized materials in electrical shielding is aluminum. It has excellent electrical conductivity and a high strength-to-weight ratio. It is also straightforward to work with and form. It is also a highly flexible material, allowing for quick prototyping and changes when needed. In each case, its use is based on the application of the material.

EMI shielding is commonly performed with steel or aluminum. Aluminum offers a low-cost solution to shielding but is highly effective owing to its non-ferrous properties. Steels containing pre-tin plating are also suitable for shielding. Copper and aluminum are common materials for EMI shielding.

Silicone

The market for silicone for electromagnetic shielding is driven by the increasing consumer electronics and 4G/LTE deployment. According to a report by the India Brand Equity Foundation, the number of mobile subscribers in India was 560 million in 2018 and is expected to reach 1.42 billion in 2024. In addition, 80% of smartphone users in India will use 4G/LTE networks. Silicone has several advantages over other materials for electromagnetic shielding.

Its low electrical conductivity makes it useful for shielding in electromagnetic fields, such as those caused by high-voltage equipment. Some silicones are electrical insulators, while others are not. Those suited for this purpose include silicones modified with vulcanizing agents or fillers. Custom fabricators can obtain silicone materials according to their specifications. Silicone can be used for electromagnetic shielding for both high-voltage and low-voltage equipment.

Intercalated graphite fibers

Graphite-based materials have been used for electromagnetic shielding for more than 30 years. They are made of flake graphite and were electrolessly plated with nickel. This process enhanced their magnetic permeability, and they were mixed with wood fiber to provide broadband shielding. The intercalated graphite fibers are made with increasing densities of carbon. Increasing the density of the fibers increases their electrical conductivity by one order of magnitude. The fibers have been tested in several applications, including electrically sensitive devices. The fibers’ electrical conductivity and ampacity are also improved. This makes them highly suitable for use in shielding systems for electromagnetic fields.

Silver-aluminum

The performance of Silver-aluminum for EMI shielding is based on two fundamental concepts. First, the metallic alloy is conductive. Second, the material has an efficient electronic transport network structure. Third, the alloy can effectively reflect electromagnetic waves. Lastly, silver films exhibit high conductivity and excellent EMI shielding performance. Nevertheless, this method does not apply to all metallic alloys. To design an effective electromagnetic shield, metallic alloys must have a d/d ratio of at least 1.3.

In the U.S., Silver-aluminum alloys are widely used as fillers. The popularity of the particles can be attributed to the U.S. military’s MIL-DTL-83528 specification. In 2011, silver was worth $50 per Troy ounce, a record high in the metal’s history. As the price of the metal fluctuates, so does the cost of Silver-aluminum.