The main purpose of effective EMC (electromagnetic compatibility) shielding is to prevent electromagnetic interference (EMI) or radio frequency interference (RFI) from impacting sensitive electronics.

EMI shielding can be considered the most cost-effective method of EMC compatibility since it decreases the use of intra-equipment devices to manage undesired signals. Achieving EMC through shielding depends on two factors: the structural or form design and the materials used.

A simple EMI shield design is a Faraday cage made of conductive materials such as copper. The EMI shield design depends on the characteristics of the electromagnetic environment within which the equipment must reliably function.

In general, the structural design of a Faraday cage should be sure that discontinuities are minimized to control leakage of radiated EMI. Additionally:

• Sufficient bonding of enclosures must be created at every seam and discontinuity to have a homogenous conductive surface. There should be metal-to-metal contact done through welding, brazing, or soldering.
• Generally, similar metals are bonded to prevent galvanic corrosion.
• The poorest electrical bond will determine the shielding effectiveness of the enclosure.
• In case permanent bonding is not possible, ensure that the chosen fastening method exerts enough pressure to maintain contact.
• For uneven surfaces, it is best to use an EMI shielding gasket. EMI shielding gaskets are commonly used for enclosures with removable panels, drawers, and covers. The gaskets fill in the gaps to provide continuous electrical contact between surfaces.

EMI shields are available as solid enclosures, wire mesh, screens, gaskets, O-rings, cable shields, and coatings.

Electromagnetic interference occurs when external sources discharge energy toward devices. The unwelcome disturbance diminishes or prevents the use of the devices, and it can compromise in-flight stability.

In light of the undesirable consequences, EMI testing examines the possible causes and solutions to intervening currents.

Want to learn more? Tonex offers EMI/EMC Shielding Design Workshop, a 2-day course where participants learn the fundamentals of EMI and EMC in electronic systems as well as explore advanced concepts in EMI/EMC shielding design.