Toll Free Number: (877) 625-6033 - Email: sales@MAJR.com

Blog

All posts in Blog

Conductive Elastomers: Silicone vs. Fluorosilicone
Will Your Hardened Enclosure Remain Effective in Harsh Environments?

Conductive Silicones are often an essential component for hardened boxes and enclosures where environmental sealing and EMI/RFI shielding is required. The typical silicone-based gaskets and seals are impregnated with nickel, silver, copper, aluminum or other conductive particles to give non-conductive silicone their conductivity while providing IP rated environmental sealing that is required in many military electronic applications. These Conductive Silicone materials are also very flexible and can be formed into sheets, extrusions in various profiles, strips, washers and custom molded parts to fit almost any specific requirement, regardless of how unique.

But the one issue with these essential conductive silicone products is that they aren’t designed to withstand a harsh environment where they are regularly exposed to chemicals such as cleaning agents, oils or fuels.  Harsh chemicals cause the silicone to break down causing the environmental sealing protection and EMI shielding properties to be lost. These same Silicones can also lose their effectiveness due to galvanic corrosion between the conductive silicone product and the metal enclosure, especially in a shipboard environment. To defend your hardened box or enclosure that is exposed to chemical contamination or heavy salt fog MAJR Products recommends the use of conductive fluorosilicone materials.  This is a silicone elastomer which has been fluorinated to stop its breakdown when in contact with harsh chemicals but it maintains needed environmental sealing and EMI/RFI shielding characteristics.  “…fluorosilicone rubbers…have excellent resistance to aliphatic hydrocarbons and good resistance to aromatic hydrocarbons, oil and gasoline, animal and vegetable oils, dilute acids and alkalies, and alcohols; and fair resistance to concentrated alkalies.”¹

Like their conductive silicone cousins, conductive particles are added to the fluorosilicone base and the particles that should be used are dependent on your application.  The table below shows various options.

A comparative table of available fluorosilicone materials and uses from MAJR Products

When you consider the available number of sheets in various thicknesses or the number of extruded profiles and washers offered, MAJR Products can deliver chemical resistance, environmental sealing and EMI/RFI attenuation in a fluorosilicone component that meets your needs and exceeds your expectations.  

Fluorosilicone products in various forms from MAJR Products

Contact us by email or phone (at 877-625-6033) to discuss your unique military or commercial needs.  Our engineers will be happy to assist you in choosing the right fluorosilicone material and profile.

¹Encyclopedia of Corrosion Technology, Volume 20 of Corrosion Technology, Edition 2, revised, edited by Phillip A Schweitzer, P.E., CRC Press, 2004, ISBN 0824750446, 9780824750442, pg. 563.  

Custom EMI Ventilation Panels: An End to the “Square Peg – Round Hole” EMI Shielding Dilemma

Hardened enclosures come in all shapes and sizes.  When you compound the possibilities of various applications, industries, specifications and regulatory authorities, it’s no wonder that standard sizes, types or material for shielding a hardened enclosure rarely meet specific needs for any given project.  Even though most hardened enclosures are custom designed with specific requirements in mind they often have one thing in common: They all must breathe to allow cooling of sensitive electronic equipment while also being protecting from EMI/RFI.

Up until now this has been an ongoing problem for engineers.  Rarely are enclosures designed to be able to use standardized products for EMI shielding and air ventilation. Long and costly waits for a specialized EMI ventilation panel prototype are only the first problem.  Large production runs have been out of the question. It is almost as if the pre-existing EMI shielding vent panel dictated the size and configuration of the hardened enclosure. That’s like forcing a square peg into a round hole.

Need Round, Curved or Oddly Shaped Custom EMI Vent Panels?

MAJR Products, however, has mastered the trifecta of shape, size and speed-to-market for Custom EMI Ventilation Panels.  We are the leading EMI shielding products manufacturer that can supply specialized  vent panels engineered for difficult round, curved or specialized shape requirements and still maintain a high level of EMI/RFI attenuation and low upfront set-up costs.

Custom EMI shielded vents for hardened enclosures.

With a simple upload of specifications from a customer, MAJR Products can produce Custom EMI Ventilation Panels estimates often within a few days and provides in house technical assistance on design concerns before parts move into the production phase. In addition, MAJR’s Custom EMI Ventilation Panels can be produced in both Honeycomb Waveguide and Air Ventilation styles depending on the shielding and airflow requirements.

  • Custom Honeycomb Waveguide Panels are available in aluminum, brass, steel and stainless steel to meet the specific attenuation requirements of MIL-STD-461 and MIL-STD 810 by facilitating wavelength beyond cutoff.  While they can be made in a variety of shapes and sizes, they still allow for maximum air flow. With integrated gasketing material appropriate for the application, these custom waveguide panels can be supplied with captive fasteners or frame through-holes mounting options.
  • Custom Air Ventilation Panels also achieve attenuation of EMI/RFI noise while providing a minimal air pressure drop.  Most applications will call for an aluminum code-57 filter media and, when used with MAJR’s integrated gasket, will achieve EMI shielding to levels that meet or exceed commercial requirements.

Only from MAJR Products

We’re proud of the fact that MAJR Products is the manufacturer that can supply Custom EMI Ventilation Panels for round, curved or odd-shaped spaces more rapidly than anyone else in the industry.  We have developed internal mechanisms to incorporate custom designs into our high-capacity manufacturing and metalworking capabilities. The result:

  • No more “square peg-round hole” restrictions on honeycomb vent panel design.
  • Quick development and engineered to your specifications.

For those openings in hardened enclosures that are beyond the limits of stock, off-the-shelf EMI shielding vents, reach out today and – contact MAJR Products!  

MAJR Products EMI/RFI wire mesh grounding washers

EMI/RFI Wire Mesh Grounding and Conductive Elastomer Washers: Hardened Enclosure Shielding in Small Places

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

MAJR Products EMI/RFI wire mesh grounding washersEMI/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

Mounting application examples for MAJR Products conductive silicone washersConductive 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.

 

Besides being able to attenuate EMI/RFI noise from inside and outside the hardened enclosure, elastomer washers are used:

  • To provide moisture sealing,
  • As a shock absorber,
  • To enable electrical grounding.

Like their wire mesh cousins, conductive elastomer washers can be made in almost any ID or OD size.

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.