What EMI Shielding is and Why it Matters

In this article, you'll learn the importance of understanding EMI Shielding and what you can do to prevent interference between your electronics.

What is EMI? Why Does it Matter?

In general, EMI is the study of interference between electronic components such as your cell phone and the radio in your car. For example, some people experience noise when they’re getting a phone call in their car and it shows up through the car speakers. That’s because the car radio is picking up some of the signal from their cell phone.

We call this interference because it’s not desired. We don’t want those two to be talking to each other because they’re separate devices and they should live in separate worlds, or separate frequency bandwidths.

But unfortunately, the world is not perfect. There’s always some interference and EMI is not only the issue, but also the study of how to solve these problems.

EMI Shielding

One way to solve these problems is by using shields. Shields are mechanical devices that are essentially flat sheets that, when put around devices, prevent interference. These shields can prevent interference from either a device generating interference out to the world or the device picking interference from outside sources into itself.

The reason this topic is prevalent today is because now, more than in the past, we live in a very wireless world. Not many people had cellphones 10 years ago, but now everyone’s got one and everybody wants theirs to be the fastest and the best. This leads to overcrowding of our air with wireless signals from wifi, cellular phones, and any other kind of wireless device (such as Bluetooth) interfering with one another. It’s become a hot topic and I think it’s going to stay hot for some years.

The EMI shielding Integration Process

Before a product can be released to the public, it has to meet a certain set of standards in regards to noise interference. So it goes through a battery of tests that will prove whether this device is good enough to be put out in the market without interfering with different components such as TVs, radios, cellphones, etc.

Usually designers today are not focused primarily on fixing this problem from the beginning, they always fix it at the end after they do some testing. So we get a lot of calls from designers once they’ve gone through the first battery of tests. Their products are failing these tests because they’re not meeting the standards. So these designers will call us up and say, “How do I fix this?” Either they already have shields and they’ve tried them but aren’t getting the efficiency that they’re looking for, or they just plain don’t know how to use them and don’t have a clue as to what a good solution would be.

Our job as field applications engineers at Wurth Electronics Midcom is to guide them through the process. When it comes to shields, there’s two different kinds. There are metallic shields and ferrite shields. The two are vastly different. They are used for different applications and hence the main goal is to pick the right one for them to use. So they’ll tell us what the problem is and based on those parameters, we will pick out a solution for them.

There’s a reason we have FAEs (Field Application Engineers) at Wurth Electronics Midcom. A lot of times people need support in real-time. So there’s 4 gentlemen here in the states and throughout the world we have about 21 people who are ready to give support. Just give us a call at (605) 886-4385 or email us at midcom-us@we-online.com. One of us can answer the question for you and and if one person doesn’t know, there are 20 others. Between our backgrounds, we will most likely find a solution for your problem.