Home > > EMC/EMI Shielding Explained
18 December 2019
EMC ShieldingTraining
Written byNeilMoore
What is EMC Shielding?
EMC Shielding is any method used to protect a sensitive signal from external electromagnetic signals, or preventing a stronger signal from leaking out and interfering with surrounding electronics. It can cover PCB elements such as IC chips and active components, or connectors and cables between PCBs.
EMC is short for ElectroMagnetic Compatibility, which means that a circuit has been designed with this prevention of disruption by shielding.
Electromagnetic frequencies can affect many sensitive electronics, and can cause a wide variety of different issues from a simple hiss on a communication line, to a total disruption of a safety-critical signal. As such it affects a diverse range of sectors, including all consumer and industrial electronics, and into critical systems for military and emergency services.
Here’s everything that you need to know about EMC Shielding in a nutshell.
Download this article in PDF format
How does EMC Shielding work?
The main purpose of effective EMC Shielding is to prevent electromagnetic interference (EMI) or radio frequency interference (RFI) from impacting sensitive electronics. This is achieved by using a metallic screen to absorb the electromagnetic interference that is being transmitted through the air. The shield effect is based on a principle used in a Faraday cage – the metallic screen completely surrounds either the sensitive electronics or the transmitting electronics. The screen absorbs the transmitted signals, and causes a current within the body of the screen. This current is absorbed by a ground connection, or a virtual ground plane.
By absorbing these transmitted signals before they reach the sensitive circuitry, the protected signal is kept clean of electromagnetic interference, maximizing shielding effectiveness.
A good example in every person’s pocket is the smartphone. It is essential that EMC shielding is used to protect the sensitive electronics in the device that make it process and display information from the phone’s transmitter.
What materials can be used for EMC Shielding?
Several techniques and materials can be used for EMC Shielding, and the materials used depend on the type of electronics and frequencies involved. This is because the amount of signal reduction/blocking depends on the material used, the size of the shielded volume, the material thickness – each of these factors affects the range and strength of frequencies that can be absorbed by the shielding.
Some examples include:
- Metallic foil or plaited braid to shield equipment wires.Coaxial cablehas this EMC shield built into the wire construction, underneath an outer insulation layer. Other wire bundles can be wrapped in foil, or ready-made cable braid applied over the whole construction. The connectors on the ends of the wire would also require metal covers, and the braiding or foil needs to be attached to the metal to give total coverage.
- For shielding on PCBs (known asBoard Level Shieldingor BLS), shielding typically consists of a PCB with a ground plane built into it, and a metal box (known as a shield can) placed over the sensitive or transmitting elements. The components are then completely surrounded by a Faraday cage arrangement.
- In devices such as audio speakers, an inner metallic casing would be used to successfully block EMI produced by nearby transmitting devices (such as microwaves and TVs).
Conductive paints and magnetic materials can also be used in environments where magnetic fields are below the 100Khz range. Other methods can include sheet metal, metal foam, conductive plastics and mesh metal screening.
Depending on the frequency, the shielding does not have to be a solid screen, but can have regularly placed holes, or even just be wire fencing. It is therefore important to understand exactly which part of the electromagnetic frequency spectrum needs to be guarded against in any particular application.
Example Applications of EMC Shielding
Here’s a look at some of the ways EMC Shielding is used across a broad range of applications…
- EMC Shielding is used to protect medical and laboratory equipment, where it is vitally important and potentially life-saving to disrupt and prevent signal interference. Anything from AM/FM emergency service transmission and other telecommunications, to data communications, theatre and ward patient monitoring equipment, and even in-body medical devices such as pacemakers.
- EMC Shielding can prevent access to data stored on RFID chips or embedded in other devices.
- EMC Shielding can be used in combination with air-gapped systems to increase and complement existing security measures, such as those used in military, government and financial systems.
Ultimately, shielding is required where any sensitive electronic element requires isolation from the surrounding electromagnetic fields, or where a particular element is transmitting unwanted additional signals. In today’s technologically-dependent environment, every item needs to be considered for EMI/RFI protection.
View EMC Shielding Product Range
How can we help you?
If you would like to talk to someone about Harwin’s product, technical knowledge or documentation, contact one of our Experts for assistance.
Contact us
EMC ShieldingNew Products
17 December 2019
DatamateEMC ShieldingHigh ReliabilityNew Products
16 October 2017
EMC ShieldingNew Products
Shield Cans now available in kit form for fast, low cost development
25 November 2014
Back to Blog
Uh oh, it looks like you are using an outdated browser version.
Some functions may not work as expected on Harwin.com in your current browser. For thebest experience, more security and speed, we recommend updating your browser tothe latest version.
(if you are using Internet Explorer, we recommend switching to an alternative browser.)
View Supported Browsers
Still having issue? Contact [emailprotected] for help.
We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. By Clicking "Manage Cookies" you can see what cookies we use and adjust your settings, you can change your settings at any time. For more information view our cookie policy.
Privacy Overview
This website uses cookies to improve your experience while you navigate through the website. Out of these cookies, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may have an effect on your browsing experience.
Always Enabled
Essential cookies are vital to the successful operation of our website, for example these cookies allow you to login and download CAD drawings or order an evaluation sample.
Cookie | Duration | Description |
---|---|---|
_dc_gtm_UA-[id] | 24 hours | Used by Google Tag Manager to control the loading of a Google Analytics script tag. |
_ga | 2 years | Used to differentiate users. |
_gat_[id] | 2 years | Used to control request rate. |
_gid | 24 hours | Used to differentiate users. |
browser_details | Session | We will log your browser name and screen size to help us debug any issues. |
cableBasket | Session | Contains list of cable configuration choices added to the cable generator basket. |
cli_user_preference | 1 year | The cookie is used to store the user consent for the cookies. |
cookielawinfo-checkbox-essential | 11 months | The cookies is used to store the user consent for the cookies in the category "Essential". |
cookielawinfo-checkbox-functional | 11 months | The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". |
cookielawinfo-checkbox-performance | 11 months | The cookie is used to store the user consent for the cookies in the category "Performance". |
CookieLawInfoConsent | 1 year | The cookie is used to store the user consent for the cookies. |
currentCableBasket | Session | Contains the basket number that you're currently editing in the cable generator basket. |
JSESSIONID | Session | Used to store a unique identifier for your session. This cookie is deleted when you close your browser. |
PHPSESSID | Session | Used to store a unique identifier for your session. This cookie is deleted when you close your browser. |
sampleBasket | Session | Contains list of products and comments added to the sample basket. |
viewed_cookie_policy | 11 months | The cookie is used to store whether or not user has consented to the use of cookies. It does not store any personal data. |
wordpress_logged_in_[id] | 14 days | Used to store a unique identifier for tracking WordPress login status. |
wordpress_sec_[id] | 14 days | Used to store a unique identifier for tracking WordPress login status. |
wordpress_test_cookie | Session | Test cookie to check if cookies are enabled. |
wp_wordpress_session_[id] | 2 days | Contains a unique code for each customer so that it knows where to find the cart data in the database for each customer. |
wp-settings-[id] | 1 year | The cookie is used to customize the view of your admin interface and the front-end of the website. The value represented by [UID] is the individual user ID of the user as given to them in the users' database table. |
wp-settings-time-[id] | 1 year | The cookie is used to customize the view of your admin interface and the front-end of the website. The value represented by [UID] is the individual user ID of the user as given to them in the users' database table. |
Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features.
Cookie | Duration | Description |
---|---|---|
bcookie | 2 years | This cookie is set by linkedIn. The purpose of the cookie is to enable LinkedIn functionalities on the page. |
lang | Session | This cookie is used to store the language preferences of a user to serve up content in that stored language the next time user visit the website. |
lidc | 1 day | This cookie is set by LinkedIn and used for routing. |
Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors.
Cookie | Duration | Description |
---|---|---|
__cfduid | 1 month | Used to store a unique identifier for your session and apply security settings and improve site performance per user. |
_fbp | 3 months | This cookie is set by Facebook to deliver advertisem*nt when they are on Facebook or a digital platform powered by Facebook advertising after visiting this website. |
_hjFirstSeen | 30 minutes | This is set by Hotjar to identify a new user’s first session. It stores a true/false value, indicating whether this was the first time Hotjar saw this user. It is used by Recording filters to identify new user sessions. |
_hjid | 1 year | This cookie is set by Hotjar. This cookie is set when the customer first lands on a page with the Hotjar script. It is used to persist the random user ID, unique to that site on the browser. This ensures that behavior in subsequent visits to the same site will be attributed to the same user ID. |
_hjIncludedInSample | Session | This session cookie is set to let Hotjar know whether a visitor is included in a random sample which is used for site performance analysis. |
_hjTLDTest | Session | Registers statistical data on users' behaviour on the website. Used for internal analytics by the website operator. |
ac_enable_tracking | 1 month | This cookie is set by ActiveCampaign. This cookie is used to keep track of the site usage. |
AnalyticsSyncHistory | 1 month | Linkedin - Used to track visitors on multiple websites, in order to present relevant advertisem*nt based on the visitor's preferences. |
bscookie | 2 years | This cookie is a browser ID cookie set by Linked share Buttons and ad tags. |
fr | 3 months | The cookie is set by Facebook to show relevant advertisments to the users and measure and improve the advertisem*nts. The cookie also tracks the behavior of the user across the web on sites that have Facebook pixel or Facebook social plugin. |
lfuuid | 9 years | Tracks the individual sessions on the website, allowing the website to compile statistical data from multiple visits. This data can also be used to create leads for marketing purposes. |
prism_252406389 | 1 month | This cookie is set by ActiveCampaign. This cookie is used to keep track of the site usage. |
prism_649272005 | 1 month | This cookie is set by ActiveCampaign. This cookie is used to keep track of the site usage. |
UserMatchHistory | 1 month | Linkedin - Used to track visitors on multiple websites, in order to present relevant advertisem*nt based on the visitor's preferences. |