EMIEMCskjerming

EMI/EMC shielding, sometimes referred to in Scandinavian usage as EMI/EMC skjerming, is the set of methods and materials used to protect electronic devices from electromagnetic interference (EMI) and to limit the device’s own emissions so they do not disrupt other equipment. The aim is to achieve adequate shielding effectiveness over the target frequency range while maintaining functionality, safety, and manufacturability.

Shielding works by providing a conductive or magnetic barrier that attenuates electric and magnetic fields. Shield effectiveness is typically expressed in decibels (dB) and depends on the material, enclosure design, frequency, seams, apertures, and grounding. High-frequency shielding often uses metal enclosures or conductive coatings, while low-frequency shielding may require larger barriers and thoughtful layout. Practical shielding also involves managing gaps, feedthroughs, and ventilation to minimize leakage.

Common shield materials include copper, aluminum, and steel, as well as conductive fabrics, foils, and specialized composites. Design considerations encompass enclosure integrity, continuous electrical contact at joints, proper grounding, gasket quality, and the use of filter elements for signal and power lines that pass through the shield. Shielding is typically combined with PCB layout optimization, filtering, and careful grounding to achieve robust EMC performance.

Standards and testing for EMI/EMC shielding cover emissions and immunity, including MIL-STD-461, IEC 61000-4-x immunity tests, and various product-specific standards (e.g., EN 55032/55024). Shielding performance is verified through laboratory measurements and iterative design refinements.