EMI Shielding
EMI Shielding or Electromagnetic shielding is the practice of reducing and redirecting electromagnetic fields (EMF) typically in a confined area or space with barriers made of magnetic or conductive products and materials. These unique products and materials are often applied to electronic boxes, cabinets, and enclosures, for isolating a variety of electrical equipment and devices from their surroundings. The objective with these shielding products and materials is to reduce electromagnetic interference (EMI) through the coupling of radio waves, electromagnetic fields, and electrostatic fields in a specific application or environment.
What is the Purpose of EMI Shielding?
Understanding antennas and electromagnetic fields is the first step to understanding EMI shielding. EMI shielding is important for achieving electromagnetic-compatibility (EMC) for electronic products including digital systems.
EMI Shielding is a tactical effort within EMC design strategy to:
- eliminate external sources of electromagnetic radiation
- prevent electronic devices from interfering with its own operation (crosstalk)
- reduce electromagnetic radiation that may interfere with other electronic equipment and systems when operating in a specific environment.
- keep circuits from misbehaving as a result of ambient EMI/RFI from communication towers, aircraft, radio stations, etc…
Who Needs to Care About EMI Shielding and EMC Design?
Electronic equipment is used everywhere, often without any problem at all, however, there are several industries where it is critical to account for and strive for optimal function of electronic equipment. To make it even more complicated, with digital systems’ ever-increasing frequencies and edge rates, EMC is becoming harder to achieve. Where might EMI Shielding be critical?
In these industries, electronic devices might need to operate with high levels of security to protect data transmission as well as ensure fail-proof functionality. EMI shielding could mean the difference between leaked military secrets, medical equipment failure, disruption to public utilities access like water, electricity and gas, as well as disruption to cell, internet and other communications services.
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Military
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Industrial
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Energy
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Medical
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Secured Facilities
How Do You Shield Against EMI?
In the simplest terms, the goal is to block transmission and/or emission from devices. Depending on the device, its purpose, the potential for interference and its environment, EMI Shielding is typically comprised of a product placed on, in, or between a device or its enclosure.
Examples of where and how EMI shielding is implemented include:
- Windows or screens on devices
- Electronic enclosures
- EMI Washers - Bolts used in construction of structures
- EMI Door Gasket - Door Opening
- EMI Custom Gaskets - Door handle gasket
- EMI Gaskets for any ingress
- Honeycomb Ventilation Panels - HVAC unit
- EMI Connector Gaskets - electrical panel
- MRI rooms
- Circuit Boards
EMI Shielding Resources
What Are the Standards for EMI Shielding?
Corrosion, temperature, exposure to water or humidity, device materials, airflow, human interaction and industry and military standards all play a role in EMC Design and creating the best choice for protection of a device.
There are hundreds of electrical, product, and environmental specifications for EMI/RFI shielding products and their applications; below are some of the common in our industry that we utilize when deciding on a material(s) for an EMI/RFI gasket or honeycomb vent panel configuration for a specific customer’s application.
- MAJR Products Galvanic Compatibility Chart – based on MIL-STD-1250 (CORROSION PREVENTION AND DETERIORATION CONTROL IN ELECTRONIC COMPONENTS AND ASSEMBLIES)
- MIL-C-5541F (DETAIL SPECIFICATION CHEMICAL CONVERSION COATINGS ON ALUMINUM AND ALUMINUM ALLOYS)
- MIL-DTL-83528 (DETAIL SPECIFICATION GASKETING MATERIAL, CONDUCTIVE, SHIELDING GASKET, ELECTRONIC, ELASTOMER, EMI/RFI GENERAL SPECIFICATION)
- MIL-STD-461 (REQUIREMENTS FOR THE CONTROL OF ELECTROMAGNETIC INTERFERENCE CHARACTERISTICS OF SUBSYSTEMS AND EQUIPMENT)
- MIL-STD-464 (ELECTROMAGNETIC ENVIRONMENTAL EFFECTS REQUIREMENTS FOR SYSTEMS)
- IEEE P1302 (GUIDE FOR THE ELECTROMAGNETIC CHARACTERIZATION OF CONDUCTIVE GASKETS IN THE FREQUENCY RANGE DC TO 18 GHZ)
- IEEE-299 (IEEE STANDARD METHOD FOR MEASURING THE EFFECTIVENESS OF ELECTROMAGNETIC SHIELDING ENCLOSURES)
- MIL-STD-188-125 (HIGH-ALTITUDE ELECTROMAGNETIC PULSE (HEMP) PROTECTION FOR GROUND-BASED C4I FACILITIES PERFORMING CRITICAL, TIME-URGENT MISSIONS
- ICS / ICD 705 (TECHNICAL SPECIFICATIONS FOR CONSTRUCTION AND MANAGEMENT OF SENSITIVE COMPARTMENTED INFORMATION FACILITIES)
- MIL-STD-810 (DEPARTMENT OF DEFENSE TEST METHOD STANDARD FOR ENVIRONMENTAL ENGINEERING CONSIDERATIONS AND LABORATORY TESTS)
- NEMA Enclosures and IP rating (IEC 60529 DEGREES OF PROTECTION PROVIDED BY ENCLOSURES - IP CODE
- NSA-94-106 – (NATIONAL SECURITY AGENCY SPECIFICATION FOR SHIELDED ENCLOSURES)
- BEST PRACTICES GUIDELINE FOR ARCHITECTURAL RADIO FREQUENCY SHIELDING (REFERENCED IN ICD/ICS / ICD 705 TO BE USED FOR SCIF ENCLOSURES)
Materials and Use in EMI Shielding
While designing and selecting products and materials for EMC shielding, many factor come into play include specifications, attenuation requirements and galvanic compatibility. Different materials can provide different shielding and environmental outcomes in specific applications, let MAJR help assist with your application requirements using some of these materials and products:
Metal
- Aluminum
- Brass
- Copper
- Nickel
- Monel
- Steel
- Silver
Rubber
- Silicone
- Flourosilicone
- EPDM
- Neoprene
- Urethane
- Foam
Substrate
- Sheets
- Extrusions
- Fabrics
- Honeycombs
- Knitted Mesh
- Polycarbonates
- Glass
Free Tools for Engineers to Design EMI Shielding
Make EMC design easier, faster and more accurate.
Galvanic Compatibility Interactive
Streamline Metallic Compatibility, avoid corrosion and maximize shielding effectiveness.
CAD Tool for EMI/RFI Shielded Vent Panels
Create FREE CAD Drawings for Standard EMI/RFI Shielded Ventilation Panels.
Environmental Considerations for Shielding
Navigate EMI shielding materials available to choose the right product for shielding and environmental requirements.
EMI Shielding Calculator
Calculate Shielding Effectiveness for Printed Circuit Board Shields and Other Enclosures.
The Benefits of Using MAJR Products in EMI Shielding Design
At MAJR Products, our American-made shielding products are designed to meet all specifications for EMI applications.
EMI Shielding Design Products
Our shielding products provide an electrically conductive, low impedance, path allowing the electromagnetic field to propagate on the outer surface of the shielded enclosure or on the inner surface if the electromagnetic field is generated from electronic equipment within the shield.
Have a Question or Need a Quote?
Have a question or need additional information? Not sure where to start? The MAJR Products Team has the experience, knowledge and creativity to address all your EMI/RFI Shielding needs. Contact us today for a quote!