What Is EMI Shielding & Why Is It Important?

Electromagnetic interference (EMI) is a very real design challenge that engineers need to tackle frequently in our increasingly tech-reliant world. EMI shielding is a necessary design aspect, because electromagnetic interference can cause costly glitches or even catastrophic failures in important electronic components. Here’s a closer look at EMI, the technologies that need protected from it, and how EMI shielding accomplishes this.

Sources of EMI

Most EMI sources are split into two generalized groups: Ambient EMI and power quality issues. Ambient EMI signals can come from man-made or natural sources. Examples of ambient EMI signals can include things as varied as lighting, computer circuits, arc welders and the earth’s magnetic field flux. Power quality issues that cause EMI signals include voltage sags and spikes (such as a power surge), blackouts and brownouts and power line faults.

Intentional EMI is potentially a third risk category that is growing in the 21st century. Intentional EMI could be signals that originate from hackers or terrorists against critical non-military targets, such as the US power grid.

Technology That Requires EMI Protection

Some specific industries use technologies that require EMI shielding in order to protect them. These are industries that in some cases even have their own specific EMI signals to deal with. Here are some examples:

  • Railroad & Mass Transit: Railroads and mass transit systems often use high voltage contact switching as part of their daily operations. Subway systems require third rail shoes to protect against electromagnetic interference as well.
  • Hospitals & Medical Clinics: The medical sector uses a tremendous amount of technology that emits EMI signals and likewise requires EMI shielding. Everything from electronics in the emergency room to X-rays and life support units all require specific protection against EMI.
  • Military & Aerospace: Aerospace, military assets and critical infrastructure all face specific intentional EMI risks and threats. EMP cannons and microwave weapons present significant engineering challenges that need to be addressed.

How EMI Shielding Protects Critical Devices

The beauty of EMI protective shields is that they are made of metals that cannot be penetrated by EMI signals. Anti-EMI products can be custom designed from brass, tin-plated steel, stainless steel, nickel silver and other metals, depending on the specific function. EMI shields can be located on the outside of a specific device, or custom designed to cover and protect internal components. For EMI shielding to be effective, it needs to be designed to be an exact fit for the product that it is protecting. Laser welding must also be used to close any open seams, to prevent signals from leaking through and interfering with electronic component functions.