The Importance of EMI Shielding in Design

Designers play a crucial role in many of the products we use every day.  Not only have they dreamt up many of the life-changing technology we take for granted but they also work with engineers to improve the user experience of just about everything under the sun.

However, today’s tech-heavy world means that designers need to be cognizant of engineering challenges – such as electromagnetic interference (EMI).  This can disrupt critical systems and functions of mobile devices, industrial equipment, cars, and even medical instruments.  With that in mind, here is an overview of the importance of EMI shielding in design.

What Causes EMI?

There are three main sources of EMI, including thermal agitation, natural, and man-made.  Problems surrounding the phenomena first came to light in WWII as combatants turned to early versions of electronic devices for an edge in the global conflict.  During the early days EMI was largely a military problem but with the spread of electronics into every aspect of civilian life, the challenges in limiting its impact grew exponentially.

In terms of the first cause – thermal agitation – this is a manifestation of signal interference from the noise generated within the electronic device itself.  When left unshielded the interference effectively renders a device useless.

The second cause – natural interference – happens when signal interference is generated by natural events.  These include interference from Earth’s magnetic forces such as electrical storms and even snow.  It can also be found from solar radiation and this is the reasoning behind the development of Faraday cages, which, in theory, help to shield electronic devices from this phenomenon.  While older electronics are more prone to natural interference, this does not mean that designers need to ignore the problem.

The final cause of EMI is man-made and stems from generators, power lines, and other devices either at high-frequency or when they are not properly shielded.  Not only will man-made EMI degrade the function of the device itself but it can also impact the operation of other devices in close proximity.

Given this, man-made EMI is a major cause of signal interference in our world today and the risk of it impacting complex electronics is on reason why we still need to turn off our mobile phones when a plane is taking off or landing.

What Can Be Done?

While EMI is an engineering problem, it turns out that there is a quite a bit that designers can do to mitigate the effects.  This starts with the incorporation of special shields and gaskets as well designing to limit the possibility of thermal agitation.  Beyond this, designers should acquaint themselves with the capabilities of EMI shielding material manufacturers.  Doing so will help to improve the designer’s knowledge of available products and their uses, as well as specialized manufacturing capabilities which could assist in the production of customized solutions.

Beyond this, designers need to take into consideration the impact of ambient EMI and power quality issues on the overall fit, form, and function of the products they are working on.  Doing so will help to better design for purpose while ensuring the final iteration meets the needs of its customers.

This also includes looking at ways to limit the impact of Intentional EMI (IEMI) as countries and other actors seek ways to weaponize the phenomena to meet tactical purposes in the pursuit of military or industrial sabotage.   As such, designers of next-generation power and transportation networks not only to be concerned with EMI from the device or within the system, they also need to mindful of potential attacks – something which completely changes how one approaches design.

How Does EMI Shielding Work?

The gaskets used in EMI shielding are mechanical in nature and they are made from sheets of metal which is then formed into shapes before being fitted into the housings and enclosures of electronic devices.  In more complex devices, these gaskets can also take the form of screens, wires, and metal foams; this is due to the improved protection offered compared to old-fashioned gaskets.

By the way, EMI shielding is not just made from metals.  Many of today’s ruggedized devices rely on a silicone foam which helps to shield the device from external interference.  Not only do these foams offer a more malleable solution but can also be engineered to withstand extreme hot and cold.

Regardless of the gasket of choice, the intent is the same – shielding the device from EMI.  Given its importance to ensure the proper operation of electronic devices, EMI shielding is not only an important engineering consideration but it has become an increasingly important element in product design.  As such, EMI shielding should not be overlooked at every step of the design process.

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