In simple terms, radiated EMI emission starts from an emitting source, propagates via a radiating path and reaches a susceptible receiver. The strength of the radiated EMI is determined by the source, the media surrounding the source and the distance between the source and the susceptor1…unless there are cables in close proximity to the source or receptor, in which case all bets are off. In that case you need EMI shielding tape.

Electronic or electrical cables can compound EMI noise problems as they are major transmitter of stray signals. Unshielded cables can act as a conductor, sending direct disruption to sensitive equipment. They can also act like an antenna, spreading RF noise throughout a hardened enclosure. But they also act like a receptor, picking up stray EMI from other places. The best way to keep those signals contained along cabling is with EMI shielding tape.

EMI shielding tape is a knitted circular strip of wire mesh that resembles a gauze tube or elongated wire stocking. It’s construction is perfect for wrapping cables where conformity is needed without adding a lot of weight or bulk. It’s flexibility characteristics make it more suitable than foil tape where cables twist or bend. Using the appropriate diameter EMI shielding tape to fit the application, cables are covered in an over-wrap fashion to avoid gaps and achieve attenuation. The wrap can then be grounded at one or both ends.

Besides coming in various diameters ranging from .437” to 5.5” to form numerous possible widths for the wrap, MAJR Products offers knitted wire mesh tape in variety of metal wires. Our Sn/Cu/Fe wire, in accordance with ASTM B-520, provides 3% tin for low impedance and maximum corrosion resistance, 40% copper for maximum conductivity and 54% steel for strength and permeability. It offers superior performance characteristics in terms of pull strength (50 lbs) and elongation (100 percent). RFI/EMI shielding tape is also available in monel and aluminum wires, allowing you to choose the right material for your application without needlessly over-spending. Very few of our competitors can offer so many choices in terms of tape diameter and the material used.

Don’t let those electrical or electronic cables and harnesses become a raceway for EMI noise or an antenna for picking up and broadcasting stray signals. Overbraiding with EMI shielding mesh tape is the easiest and most cost effective way to achieve the attenuation needed for a hardened enclosure.

You can find more technical details and a spec download on a page devoted to knitted wire mesh tape on our website, where you can request free samples. You can also call or message our our engineers if you have questions about metal wire choices, proper diameters or the required overlap for your application.

¹Xingcun Colin Tong, Advanced Materials and Design for EMI Shielding, CRC Press, Taylor and Francis Group, 2009. Chapter 1.1.2.2 “Radiated EMI Emission”, pg. 6.

Every once in awhile true innovation transforms an industry.  Consider what the cloud has meant for business as it brought about data storage, access and co-worker collaboration.  Look at how the Internet of Things is frontiering cashierless shopping. Such champions in innovation will not only make the industry and applications they integrate with faster, easier or better, they change the way we think about what’s possible.  Over time these disruptors soon become the new industry standard and we wonder how we lived without them before their introduction. For the EMI/RFI shielding industry, this transformative shift is now taking place in RF absorber materials with MAJR Products’ new MAJRabsorber™.

MAJRabsorber™’s Innovative layered Construction

MAJRabsorber™ not only absorbs and dissipates but reflects stray noise. Within frequencies of 1 – 18 GHz it offers attenuation levels which greatly surpass other absorber materials on the market and, in fact, within many frequencies attenuation is more than doubled.  It achieves its effectiveness because of its “layered” construction. It has a flexible, inner conductive layer that is placed between two non-conductive layers, allowing MAJRabsorber™ to reflect stray signals radiated emissions and affiliated currents gathered by the electromagnetically reflective inner layer back through the non-conductive RF absorbing outer layers.  This causes stray noise to reflect, much like a racquetball’s energy is quickly dissipated as it bounces from one wall to another and therefore drops to the floor.  

But it is not just its attenuation ability that brings accolades to this new product. The very fabrication process that gives MAJRabsorber™ those high levels of attenuation also allow it to be useful in a number of difficult applications.

Consider the possibilities with MAJRabsorber™…

• Because of the non-conductive outer layers, MAJRabsorber™ can be placed between close circuits without fear of shorting out sensitive components while helping isolate them..
• The multi-layered approach also makes this material ultra-tough while remaining extremely flexible, which lends itself well to the production process for oddly shaped hardened enclosures, even remaining tear resistant for those difficult spaces during handling and transport.
• With one of the many supply options being roll form, MAJRabsorber™ is not only cost competitive but it allows for quick turn-around times when cutting prototypes and even large production runs. This becomes a game changer for strict deadlines and tight budgets.
• And for those enclosures which must stand up to challenging environments, engineers will be happy to note that MAJRabsorber™ is corrosion resistant and works well under both ends of the extreme temperature spectrum.

Tomorrow’s innovation for today’s EMI/RFI shielding needs:  That’s been MAJR Products’ mantra for 25 years. Look for MAJRabsorber™ in roll form (and quickly produced custom die-cuts), strips, sheets and pads in various shapes with no pressure sensitive adhesive (PSA) or PSA applied to one or both sides.  You’ll soon see it in the most progressive military or civilian electronic engineering programs, which are hopefully your own. MAJRabsorber™:  Only at MAJR Products.

The smallest details are often the ones that will determine whether an EMI hardened enclosure will be compliant or will not  meet EMC requirements. That’s especially true when it comes to the many bolts, screws, rods or shafts that need EMI/RFI shielding or grounding.  When you have to attenuate a signal or ground components of an enclosure, don’t forget the EMI/RFI wire mesh grounding or conductive washer. Here’s what you need to know:

EMI/RFI Wire Mesh Grounding Washers

EMI/RFI wire mesh grounding washers are made from wire mesh socks that look somewhat like thin knitted metal hoses before being compressed in a die to form the washer.  By altering the weight of the metal sock, various densities of washers can be made to increase or decrease the resilience. For example, a sock with a metal density of 15 to 20 percent will create a washer that can fill a gap or seam under pressure.  A starting density of 30 to 40 percent can create a washer which will snuggly fit a shaft or rod, which when compressed will act as a slip-ring to ground a rotating shaft to a metal enclosure. This gives the shaft needed EMC properties, eliminating unwanted EMI/RFI noise.

Besides needing to vary the thickness and density of EMI/RFI wire mesh washers, specific applications and environments often call for specific metals used in the mesh socks.  MAJR Products, for example, offers wire mesh grounding washers made of Monel, aluminum, silver plated brass, tin plated copper clad steel or beryllium copper. By varying the materials, density, thickness and inside/outside diameters, there are countless configurations and options available for any need or application within a hardened enclosure for both military and commercial uses.  This gives the engineer an impressive lineup of options. Popular applications include:

• Signal and power connector panels
• Door handle shafts
• Hinge hardware
• Grounding metal structures (i.e. equipment racks) to an electronic or electrical enclosure

EMI/RFI Conductive Elastomer Washers

Conductive elastomer washers for EMI shielding and grounding are molded elastomer filled with conductive particles to provide the electrical conductivity and broadband shielding.  They are made of a variety of materials including silicone, fluorosilicone, or EPDM which stands up to fuel or chemical contamination. Their conductive particles can be aluminum, copper, nickel or silver, used singularly or in various compound combinations.  The various conductive materials used changes the performance characteristics of the washers and, along with varying the thicknesses, allows the washers to achieve a desired hardness and operating temperature range while accommodating differing MIL SPEC M83528/012X requirements.

As stated earlier, the smallest details are often the most important when achieving attenuation and grounding in hardened enclosures.  With so many choices of materials, applications, where they are used and differing FCC, military and UL requirements, it’s important to use the right washer made of the right materials in the right size for any specific application.  There will be times when a conductive washer should be used over a wire mesh washer, or where silver is the preferred conductor over Monel or aluminum. But that’s the beauty of EMI/RFI grounding washers – they’re as adaptable as need be.

For help in determining what and how to use when, please contact the engineers at MAJR Products by calling 877-625-6033, or feel free to ask questions using the form on either of our web pages for EMI/RFI Wire Mesh Washers or Conductive Silicone Washers.