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Guidance for Designing an EMI Shielded Enclosure

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    Shielding sensitive devices from electromagnetic interference (EMI) is a critical consideration, but it doesn’t often require you to shield your entire device from EMI. More often, you just have to shield a particular part within the device, regardless of whether the potential EMI is coming from external sources or another source within the device. This is exactly what EMI shielded enclosures are meant for.

    If you’ve reached the step in the design process in which you realize that you need an enclosure that can shield from EMI, you’re at a critical junction. The effectiveness of this enclosure will very likely determine the entire device’s ability to function properly. You have to make it perfect while also keeping in mind your budget and any external design specifications you have to satisfy.

    In other words, you probably need some guidance. And you’re in the right place. The expert team at Modus Advanced has put together this quick and simple list of tips for designing an EMI shielded enclosure to help you avoid critical mistakes that can sink your entire design. Read on.

    We’re proud of the EMI shields the Modus team is able to produce. Our near-perfect results are the product of decades of experience, hard work and a healthy helping of engineering and manufacturing expertise. If you want some of all of that for your design, reach out.

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    5 Tips for Designing a Perfect EMI Shielding Enclosure

    If your EMI shielded enclosure isn’t right, you’re faced with the expensive and time-consuming task of taking it back to the drawing board to figure out what went wrong. Otherwise, you’ll have an ineffective or possibly even dangerous device on your hands. We’re here to make sure none of that happens to you. Start with the five key tips below.

    1. Select the Right Materials for Your EMI Shielded Enclosure

    Unless you’re very new to the EMI shielding world, you understand that you have several EMI shielding materials to choose from. These are typically metals like silver, aluminum, nickel and copper — sometimes alone and sometimes in combination with one another. 

    You might as well pick a shielding material out of a hat, right? Wrong. When you’ve specifically designed an EMI shielded enclosure, you have to consider several factors as you select shielding materials. 

    For example, you need to consider your project budget. Silver is a highly effective shielding material, but it’s expensive. On the other hand, graphite is more affordable, but you may sacrifice a little on the shielding effectiveness side. That sacrifice can pose a huge problem in designs meant for military applications, for which you must meet the military standard for EMI shielding: MIL-STD-285.

    2. Keep Galvanic Compatibility in Mind

    The materials that make up your EMI shielded enclosure are ostensibly going to come into contact with other parts of your device, such as the metal or plastic housing. That’s no problem until galvanic corrosion becomes a concern.

    Galvanic corrosion occurs when two metals touch each other and exchange electrons. If you’re dealing with a metal housing and metal filler material, you’re going to need to know whether the two metals involved are galvanically compatible. Otherwise, you risk selecting an EMI shielding material that will degrade the metal housing surrounding your enclosure.


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    3. Choose the Right Gasket Manufacturing Method

    You’ll need a gasket to seal the two sides of your enclosure, making it a critical component in determining the shielding effectiveness of the enclosure as a whole.

    Form-in-place (FIP), extrusion, die cutting — there are plenty of ways to manufacture gaskets and similar EMI shielding implements. But which is right for your unique design? You’re going to need to know the answer as you design your EMI shielding enclosure.

    FIP, in which EMI gaskets are dispensed directly onto their housing in liquid form, is typically ideal for intricate and/or very small applications, including small or complex EMI enclosures. This method also cuts down on material waste, possibly making room in the budget for a more expensive shielding material like silver. However, extrusion and die-cutting have their place in shielding enclosure design, too — especially for larger enclosures or those that will be sealed and unsealed frequently.

    4. Where Possible, Opt for Compression Stops, Not Grooves

    As you’re designing your EMI shielding enclosure, you may find yourself leaning heavily on grooves in which an FIP EMI gasket will be dispensed. This might be a mistake.

    That’s because dispensing EMI gaskets into narrow grooves can cause the liquid gasket material to cure more toward one side of the groove than the other, creating a potentially ineffective seal and subpar shield. The quick fix? Opt for compression stops instead of grooves whenever possible in your enclosure design.

    5. Pick a Sufficient Dispensing Length

    If you’re including an FIP EMI gasket in your EMI shielded enclosure design, you need to make sure the intended dispensing length is long enough to make sense for this manufacturing method. Really, you don’t want extremely short segments. This can cause problems during dispensing and make your design much more difficult to manufacture on the whole.

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    Bonus Tip: Work with Modus Advanced

    This is a blog post on the Modus website, so we’re willing to bet you’re not surprised to find out that we think we are a pretty good partner for producing EMI shielded enclosures and gaskets. 

    But believe us when we tell you the suggestion to work with our expert manufacturing and engineering team on your EMI shielded enclosure could be the most valuable tip there is to give. We’re here to quite literally make the difference between an ineffective and costly enclosure and one that works exactly as intended and squarely within your budget.

    It’s what we do, plain and simple. And we can do it for you, too. Ready to learn more about how the Modus team can help you get your EMI shielding enclosure exactly right? We’ve got plenty to say about that. Just give us a call at (925) 960-8700 or contact us online to get started.


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