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

Posted on September 19, 2018 by brian in Blog with Comments Disabled

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

Posted on August 15, 2018 by brian in Blog with Comments Disabled

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

Posted on July 19, 2018 by brian in Blog with Comments Disabled

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.

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.

Honeycomb Waveguide Panels

Posted on October 27, 2017 by brian in Articles with Comments Disabled

Honeycomb Waveguide – An Attenuation Performance Explanation of a MAJR Products Honeycomb Waveguide Panel due to the Effect of a Waveguide Beyond Cuttoff Principle

What is a honeycomb Waveguide panel?

A shielding honeycomb waveguide panel is a product that lets air flow into and out of an EMI/RFI shielded enclosure. The entering fresh air may be either cooled, heated, or at ambient temperature depending on the shielded enclosure environment and contents. For electronic equipment, the primary reason for airflow is usually to cool electronics; if a manned military shelter the reason is to circulate fresh air and to either cool or heat the air depending on the external environment.

How a shielded honeycomb waveguide panel attenuates

Depending on the wavelength of the electromagnetic wave entering the honeycomb waveguide panel, every cell of the metal honeycomb core provides attenuation (shielding) to that electromagnetic wave and is described as a waveguide below cutoff.

Each individual honeycomb cell acts as a waveguide and because the honeycomb cell aperture (height and width) is much smaller than a half wavelength of the electromagnetic wave entering the honeycomb, the honeycomb cell attenuates the wave.

Attenuation is accomplished by increased wave impedance and reflection cancellation as the electromagnetic wave propagates through the honeycomb waveguide thickness and number of cells. The thicker the honeycomb cell, the more attenuation the honeycomb panel will provide, therefore an approximation is Attenuation (dB) = 28 x Thickness / width.

Depending on the polarization of the electromagnetic wave, the only frequencies of the electromagnetic wave that pass without attenuation through the honeycomb cells are those that have a half wavelength dimensionally smaller than the diagonal dimension of the cell.

Applications of a Shielded Honeycomb Waveguide Panel

Custom honeycomb panels designed to meet specific shielding, airflow, and mounting requirements.
Honeycomb is available in aluminum or steel with tin, nickel, or chromate(aluminum) to meet specific attenuation and environmental requirements of MIL-STD-461 and MIL-STD 810.
High permeability steel honeycomb available for magnetic (H-Field) shielding to 60 dB attenuation levels. (>80 dB attenuation using 1 in. thick tin plated steel honeycomb).
Standard and custom sizes and mounting configurations available.
An EMI/RFI gasket is always supplied as an integral part of the honeycomb vent panel assembly.
Honeycomb panel mounting is accomplished with either frame thru-holes or captive fasteners located and installed to standard or custom dimensions.

To learn more about MAJR’s Honeycomb Waveguide Panels or other products, like: EMI/RFI Shielded Ventilation Panels, EMI/RFI Shielded Fan Ventilation Panels, EMI/RFI Shielded Air Filtration Panels, or EMI/RFI Shielded Honeycomb Ventilation Panels, visit our website and fill out the form or call us at 877-625-6033.

MAJR Products – Blog – ConnectorGasket.com: The Convenient, Quick, and Cost-Effective Way to Order Connector Gaskets Online

Posted on September 26, 2017 by brian in Articles with Comments Disabled

An engineer and a purchasing manager holding a tablet discuss what size connector gaskets to order from ConnectorGasket.com.

ConnectorGasket.com: The Convenient, Quick, and CostEffective Way to Order Connector Gaskets Online

When ordering connector gaskets, military contractors and electronics, IT, andtelecommunication companies often find it challenging to find suppliers that both offer a comprehensive range of gaskets and can deliver orders within a short period of time. As a result, procurement professionals, purchasing managers, and others responsible for buying materials frequently spend hours researching suppliers looking for one that can cater to their specific needs. Since it is so difficult to find the combination of choice, quality, speed, and cost-effectiveness, it is not unusual for them to have to order from multiple suppliers to meet their various requirements.

ConnectorGasket.com

That is why in June, we launched our new website, ConnectorGasket.com. It is specifically designed to provide our customers with a convenient, quick, and cost-effective way to fulfill all their connector gasket needs with just a few swipes, taps, or clicks.

To cater to the needs of customers from the military, consumer, industrial, instrumentation, and medical electronics sectors, as well as from the IT and telecommunications industries, we offer affordable QPL-qualified gaskets and commercial grade gaskets. There are currently four styles available for online purchase:

The MIL-DTL 38999 series
The M83528 series
The MIL-DTL 5015 series
The D-Subminiature series

By creating their own accounts, customers can keep track of their orders and easily re-order when needed. Plus, by selecting the two-day delivery option, customers never have to hold up their production cycles due to late deliveries, thereby ensuring they can fulfill their own orders as scheduled. Companies that have factored long delivery times into their own production cycles—and by extension, into their order fulfillment capabilities—can leverage our fast delivery to reduce their production cycle times and offer their own customers speedier turn-around.

Customers are also encouraged to visit our main site, MAJR Products, where we offer many other types of gaskets, including military EMI/RFI shielding gaskets and custom-made gaskets that can be manufactured to companies’ precise specifications.

Interested to learn more? Go to ConnectorGasket.com to browse our products, place your first order, or request more information.

Sources:
Creative brief
Press release June 19

Connector Gaskets

Shielding For RF And Microwave Applications

Posted on May 31, 2017 by brian in Articles with Comments Disabled

Understanding Shielding for RF and Microwave System Applications

Any electronic device emits some level of electromagnetic radiation. Electromagnetic interference (EMI) shielding and radio frequency interference (RFI) shielding products are used when the EMI/RFI of an electronic product or system, in particular high frequency operations, necessitates attenuation of EMI/RFI to a specific level; the attenuation of a radiated emission to a certain level is designated in industry as shielding. MAJR Products EMI/RFI shielding solutions are able to meet even the most stringent EMC requirements.

Why Shielding Products Are Necessary

Understanding antennas and electromagnetic fields is the first step to understanding EMI/RFI shielding. EMI/RFI shielding is important for achieving electromagnetic-compatibility (EMC) for electronic products including digital systems. EMC design is concerned with preventing electronic devices from not interfering with its own operation (crosstalk) in addition to the reduction of electromagnetic radiation that may interfere with other electronic equipment and systems when operating in an intended environment.

EMC design also involves preventing circuits from misbehaving as a result of ambient EMI/RFI from communication towers, aircraft, radio stations, etc… With digital systems’ ever-increasing frequencies and edge rates, EMC is becoming harder to achieve.

The shielding products produced by MAJR Products can be designed and manufactured to suit the unique needs of specific customer applications. In addition, with experience designing custom EMI/RFI shielding products, the engineers at MAJR Products offer customers flexibility from design, through prototyping / test, and into production.

A Wide Range of Microwave Absorber Materials

While EMI/RFI Shielding has long been a requirement for military applications’ such as in high frequency electronics, there is also a growing need for microwave absorbing materials in consumer electronics such as wireless LAN devices, network servers, video equipment etc. Depending on the requirements of the application, microwave absorbing material can be tuned to function best at specific frequencies or designed to be used across a broadband frequency range. Along with tuned microwave absorber materials, Broadband microwave absorbing material is used in electronic products for a wide variety of markets including cellular and telecom, RFID tags, electronic devices, radar cross section reduction, and a variety of other antenna and electronic enclosure applications.

Broadband Microwave Absorber Material and Board Level Shielding from MAJR Products

For shielding of RF and microwave applications, MAJR Products 6500 series Broadband Microwave Absorber material product line utilizes material that is elastomer-based, ultra-soft, thin, flexible, and easy to install in even the tightest of applications or irregular surfaces. This absorber can be supplied die cut or water jet cut to meet the exact product specifications. In addition, for installation ease the absorber can be supplied with a pressure sensitive adhesive, typically requested for use in general to high altitude or high vibration applications.

MAJR Products’ Board Level Shields (BLS) are manufactured specifically to meet the requirements of an individual project, we offer the following:

Custom Tailored Configurations: using Precision Photo Etching or Stamping techniques, MAJR can supply custom tailored solutions in a matter of weeks.
Multiple Types/Materials: diverse material options and styles mean you can select the configurations and features needed for your application. Available materials include:
- Nickel/Silver
- Tin/Steel
- Brass
- Copper
- Magnetic Shielding Material
- Others per request
Special Design Features/Finish: providing flexibility for mounting, solder techniques, pick and place automation, lid placement alignment, marking, and overall dimensional flexibility.

Contact MAJR Products For A Quote On Shielding Products For RF And Microwave Applications

See how MAJR Products can solve your electronics shielding equipment needs. Contact us for additional product information, free sample products, or to receive a quote on shielding solutions for RF and microwave applications.

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