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What is EMI/RFI Shielding?

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    Hold out your hand. Wave it. You felt nothing more than the slight movement of the air, right? You may not realize it, but you very likely just waved your hand through electromagnetic and radio frequency disturbances. If you were an unprotected electronic device, you would have felt it.

    Our world is filled with invisible signals flying through the air and moving along conductive surfaces. As we create more electronic devices, we generate more of these signals. And electromagnetic interference (EMI) and radio frequency interference (RFI) become even more common.

    The problem? EMI and RFI can interfere with electronic devices, disrupting their functions or leaving them useless. Fortunately, this is a problem we can solve. The solution is EMI/RFI shielding.

    Modus Advanced didn’t write the book on EMI/RFI shielding, but we did write the definitive guide. Check it out.

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    Electromagnetic Interference (EMI) / Radio Frequency Interference (RFI) Shielding Definition

    Let’s begin with a simple definition:

    What is EMI/RFI shielding?

    EMI/RFI shielding is the process of reducing interference from external electromagnetic signals that can disrupt the function of electronic devices. Engineers and designers create effective EMI/RFI shields by selecting materials that attenuate electromagnetic signal strength and placing them around the sensitive areas of the device. This is usually done in the form of a gasket or similar seal.

    That’s the simplified answer, but there’s a lot more to know about this concept. Read on.

    EMI/RFI Shielding FAQs

    Over the years, the Modus team has received a lot of questions from customers about EMI/RFI shielding. These questions tend to go a lot further than the simple, “What is EMI/RFI shielding?” There’s plenty to ask, and we have plenty of answers. We’ve answered a few of the most common questions below.

    What is the Difference Between EMI and RFI?

    You may see the terms EMI and RFI used interchangeably, but that’s not entirely accurate. Think of the difference between EMI and RFI like the difference between dogs and golden retrievers. 

    All golden retrievers are dogs, but not all dogs are golden retrievers. Similarly, all RFI is EMI, but not all EMI is RFI. The distinction here is about the frequency of the interfering signal. Any frequency that can cause electrical interference is EMI, but RFI refers only to signals that fall into the frequency range used for radio transmissions — usually somewhere between a few kilohertz and 30 megahertz.

    What Kinds of Materials Act as EMI/RFI Shields?

    Any material that attenuates a disruptive electromagnetic signal can be considered an EMI/RFI shield, but the shielding materials used in electronic devices are typically some kind of metal. In EMI/RFI shielding gaskets, the most common shielding materials are as follows:

    • Silver
    • Silver aluminum
    • Silver nickel
    • Silver copper
    • Nickel graphite

    In gaskets, these materials are usually a “filler” inside a base material, which is typically made from silicone or fluorosilicone. When electromagnetic emissions reach the gaskets that contain these filler materials, the signals are reflected or absorbed.


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    How Does Shielding from EMI and RFI Protect Electronic Devices?

    By attenuating electromagnetic signals before they reach critical components of electronic devices, EMI/RFI shields can prevent everything from minor crackling in telecommunications broadcasts to deadly malfunctions in aircraft safety equipment. When left unmitigated, external electromagnetic signals can disrupt the essential functions of electronic devices. 

    For example, medical equipment that monitors patients may have its monitoring capabilities disrupted by an errant signal. Electromagnetic signals can also erase or damage data in all kinds of electronic equipment. Even satellites in space need to be shielded from EMI/RFI in order to function properly.

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    What Are Some Common Sources of EMI/RFI?

    What is EMI/RFI shielding protecting devices from, exactly? In the modern world, the answer is almost everything.

    Cell phones, microwaves, cell networks, ignitions, power lines, and computer circuits are just a few examples of human-caused EMI and RFI. But then, you have to consider the natural causes of these disruptive signals, with auroras, solar flares and lightning being some of the most common examples.

    In Which Industries is EMI/RFI Shielding Important?

    Nearly any industry that uses or produces electronic devices that are susceptible to electromagnetic interference can benefit from EMI/RFI shielding. The following are some of the industries that rely on EMI/RFI shielding most heavily:

    Each of the above industries has a direct interest in reducing interference from external signals, with the potential complications ranging from low-quality audio transmissions to total failure of a rail control system.

    High-Tech, High-Quality EMI/RFI Shielding

    Shielding devices from EMI and RFI is only going to become more important with time. Designing effective EMI/RFI gaskets and other parts is already an enormous consideration for any device, and it’s going to stay that way. 

    At Modus Advanced, we’re prepared for that. Our team of manufacturing experts and engineers is dedicated to supporting you throughout the design process — from idea to ignition — to make sure your device meets every last specification, effective shielding included.

    What is EMI/RFI shielding? It’s an important part of what our team can help you with as you bring your design from concept to concrete. Interested in working with us? Reach out. Give Modus Advanced a call at (925) 960-8700 or contact us online today.


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