View Specsconductive elastomer gaskets overview

EMI Materials Introduction

- Availability

- Design Flexibility

- Cost Effectiveness

- Proven Performance

…just four of the reasons why conductive elastomer gaskets are so often the right EMI shielding solution! Once used mainly to shield critical defense and aero- space electronic systems, Parker Chomerics conductive elastomers have become the progressive choice for packaging designers of consumer, telecommunications, business, industrial equipment, automotive, medical devices and much more.

Conductive elastomers are reliable over the life of the equipment. The same gasket is both an EMI shield and an environmental seal. Elastomer gaskets resist compression set, accommodate low closure force, and help control airflow. They’re available in corrosion- resistant and flame-resistant grades. Their aesthetic advantages are obvious.

Almost any elastomer profile can be extruded or custom-molded with modest tooling costs and short lead times for either prototypes or large orders. Parker Chomerics can take a customer-supplied design and deliver finished parts, typically within just a few weeks. Parker Chomerics offers hundreds of standard molded and extruded products. Molded products provide moisture/pressure sealing and EMI/EMP shielding when compressed properly in seals, flanges, bulkheads, and other assemblies. Extrusions provide similar benefits and are also readily lathe-cut into washers, spliced, bonded, kiss-cut, or die-cut to reduce installation labor and to conserve material, resulting in a cost-effective alternative to other methods of EMI shielding and environmental sealing.

 

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CHO-SEALL® Elastomers for Typical Commercial and Military Applications
(M = Molded only, E = Extruded only, F = Fluorosilicone)
Material Filler and Binder Equipment Shielding Requirements (Typ.) Remarks
CHO-SEAL 1224 (M) Silver in silicone > 120 dB Highest shielding effectiveness and through conductivity performance; higher physical properties; excellent processing; also available in a fabric reinforced format.
CHO-SEAL 1221 (M) Silver in fluorosilicone > 120 dB Highest shielding effectiveness and through conductivity performance; higher physical properties; excellent processing; also available in a fabric reinforced format.
CHO-SEAL 6502 Nickel-plated aluminum in silicone > 100 dB Highest performance in harsh environments; excellent shielding; best choice for corrosion requirements against aluminum.
CHO-SEAL 6503 Nickel-plated aluminum in fluorosilicone > 100 dB Highest performance in harsh environments; excellent shielding; best choice for corrosion requirements against aluminum.
CHO-SEAL 1298 Silver-plated aluminum in fluorosilicone 90 - 110 dB High performance in harsh corrosive environments; material of choice for aircraft and marine military applications; good physical properties; molded, extruded and reinforced product forms.
CHO-SEAL 1285 Silver-plated aluminum in silicone 90 - 110 dB Military grade gasket for corrosive environments; lightweight, 200°C max use temperature; good EMP resistance; molded, extruded and reinforced product forms.
CHO-SEAL 1287 Silver-plated aluminum in fluorosilicone 90 - 110 dB Military grade gasket for corrosive environments; lightweight, 200°C max use temperature; good EMP resistance; molded, extruded and reinforced product forms.
CHO-SEAL 1215 Silver-plated copper in silicone 105 - 120 dB Resists highest level of EMP induced current; military gasket of choice in non-corrosive environments; excellent processing for molding and extrusion.
CHO-SEAL 1217 Silver-plated copper in fluorosilicone 105 - 120 dB Resists highest level of EMP induced current; military gasket of choice in non-corrosive environments; excellent processing for molding and extrusion.
CHO-SEAL 1273 CHO-SEAL 1270 (M) Silver-plated copper in silicone 80 - 105 dB Material of choice for high-end commercial applications; superior performance in non-corrosive environments; tear trim compression and injection molding. 1270, a low durometer hardness elastomer, is recommended for applications requiring low compression forces.
CHO-SEAL S6305, 6330(M), 6370 (E), 6371 (M), 6372 (E), 6308 (E) Nickel-plated graphite in silicone 100 dB100 dB Good performance in moderately corrosive environments; material of choice for flange finishes needing “bite-through” for good electrical contact. Flame retardant 6370(E) and 6371(M) are UL 94 V-0 rated. 6330 and 6372(E) are UL 94 V1 rated, 6308(E) is designed for thin wall extrusions; 6330(M), a low durometer hardness elastomer, is designed for applications requiring low compression forces.
CHO-SEAL L6303 Nickel-plated graphite in fluorosilicone
CHO-SEAL 1350 Silver-plated glass in silicone 80 - 105 dB Standard material for high volume injection and compression molding and small extrusions; high performance in non-corrosive environments; used in grounding applications with little or no vibration.
CHO-SEAL 1310 (M) Silver-plated glass in silicone 80 - 100 dB Moderate performance in non-corrosive environments; no corrosion or fluid resistance; material of choice for small, delicate injection-molded parts or large dimension extrusions.
CHO-SEAL 0860 (E), 0862 (E) Carbon in silicone 30 - 80 dB Low-end shielding and ESD protection; high tensile strength; no corrosion or fluid resistance. 0862(E) is UL 94 V-0 rated.
CHO-SEAL S6600 (M) Carbon in silicone 30 - 80 dB Low-end shielding and ESD protection; high tensile strength; no corrosion or fluid resistance. Molded only.

 

 


 

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Specialty Elastomers
(M= Molded only, E = Extruded only)
Material Filler and Binder Equipment Shielding Requirements (Typ.) Remarks
CHO-SEAL 1401 Silver in reticulate silicone 80 -100 dB High performance for non-corrosive environments; soft (45 Shore A) for low closure force where gasket geometry cannot be exploited; low tear strength; no fluid resistance.
CHO-SEAL 1239(M) Silver-plated copper in silicone with expanded copper reinforcement 110 dB Material for waveguide choke, cover, and flange EMI shielding and pressure sealing; maximum heat transfer and minimum outgassing; hard (80 Shore A), high-strength material; available with raised lip around iris opening for high power/high pressure applications.
CHO-SEAL 1212(M) Silver-plated copper in silicone 120 dB High strength, hard (80 Shore A) material for waveguide, choke, cover, and flanges with grooves for EMI and pressure sealing.
CHO-SEAL 6435(M) Silver-plated nickel in EPDM 95 dB Material of choice for high shielding effectiveness where NBC fluid resistance is needed; good performance in corrosive environments.
CHO-SEAL 6307(M), 6452(E) Nickel-plated graphite in EPDM > 90 dB Good performance in moderately corrosive environments; excellent NBC fluid resistance; good physical properties.
CHO-SEAL V6433(M) Silver-plated nickel in fluorosilicone/fluorocarbon 100 dB Material of choice for extensive fluid resistance; no corrosion resistance.

 

 


 

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CHO-SEAL®CONDUCTIVE ELASTOMERS

Over the years, Parker Chomerics has developed and enhanced virtually every aspect of conductive elastomer materials technology, from the earliest silver and silver-plated copper filled silicones, to the latest and more cost-effective silver-plated aluminum and nickel-plated graphite composites. Today we offer the most comprehensive selection and highest quality products available.

Each conductive elastomer consists of a silicone, fluorosilicone, EPDM or fluorocarbon-fluorosilicone binder with a filler of pure silver, silver-plated copper, silver-plated aluminum, silver-plated nickel, silver-plated glass, nickel-plated graphite, nickel-plated aluminum or unplated graphite particles.

The development of these composites is the result of decades of research and testing, both in the laboratory and in the field. Our proprietary filler powder technology allows us to carefully control the composition, size, and morphology of the conductive particles. Their precise, uniform dispersion within the resinous binders produces materials with stable and consistent electrical and physical properties.

Parker Chomerics’ conductive elastomers feature excellent resistance to compression set over a wide temperature range, resulting in years of continuous service. In addition to EMI shielding, these materials can provide an environmental or pressure seal if required.

For those materials containing silver, both packaging and storage conditions should be similar to those for other silver-containing components, such as relays or switches. They should be stored in sheet plastic, such as polyester or polyethylene, and kept away from sulfur-containing materials, such as sulfur-cured neoprene, cardboard, etc. To remove dirt, clean the elastomer with water or alcohol containing mild soap (do not use aromatic or chlorinated solvents). Shelf life of these conductive elastomers without the presence of pressure sensitive adhesive (PSA) is indefinite.

The tables in this site outline the properties and specification limits of Parker Chomerics’ conductive elastomers. These materials are produced in a virtually unlimited variety of molded, die-cut and extruded shapes and sizes. Our Applications Engineering Department is very accessible, and ready to assist with material selection and gasket design. We welcome your inquiry.

 


 

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MATERIAL SELECTION

The Parker Chomerics array of conductive elastomers offers true flexibility in selecting the appropriate material for a specific application on the basis of cost and level of attenuation required. Price varies directly with shielding performance.

For typical military/aerospace applications, we recommend that users of conductive elastomer gaskets specify that materials meet the requirements of MIL DTL- 83528 QPL sources. To avoid the risk of system EMI or environmental seal failure, any change in conductive elastomer seal supplier (including MIL DTL-83528 QPL suppliers) should be preceded by thorough system qualification testing.

 


 

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Fluid Resistance of Non-Silicone Based Elastomers

Certain specialty elastomers and fluorosilicone based materials, are offered specifically for their fluid resistance properties. Table 6 illustrates the qualitative assessment of fluid resistance towards various fluids for three non-silicone binders used for Parker Chomerics conductive elastomers.

 


 

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Conductive Elastomer Applications

In general, certain types of Parker’s conductive elastomers are specified more often for military/aerospace applications or for commercial applications. However, there is a considerable overlap, and our Applications Engineering department will be pleased to assist you with your product selection.

 


 

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Conductive Elastomer Selection Guide

The tables contained in this site provide selection guidelines for Chomerics’ most general-purpose EMI elastomer materials. With the exception of certain limitations noted under “Remarks”, these materials are electrically stable over time and provide excellent moisture and pressure sealing. They are all medium durometer materials and differ mainly in shielding performance and corrosion resistance. (Nickel-plated aluminum materials are significantly more corrosion resistant than silver-plated copper, silver-plated aluminum, and silver-plated nickel filled materials against aluminum.)

Note on Gasket Deflection and Closure Force:
We do not recommend basing material selection primarily on hardness. Unlike unfilled elastomers, material hardness is not always an accurate indicator of deflection properties. The geometry of the gasket is generally the most important
determinant of deflection under load. For applications requiring large gasket deflection with minimum closure force, a hollow part geometry is recommended. Please refer to the product specification data for technical information regarding:

• Compression-Deflection
• Stress Relaxation
• Compression Set
• EMP Survivability
• Vibration Resistance
• Heat Aging
• Outgassing
• Volume Resistivity

 


 

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Top Corrosion Resistant Materials

CHO-SEAL 6502 and 6503 gaskets with Ni/Al particles provide the material of choice for corrosion resistance against aluminum in harsh environments. These materials have lower transfer impedance at frequencies >10 MHz providing more than 100 dB of shielding effectiveness. After 2,000 hours, 125°C heat aging life testing, the shielding effectiveness is virtually unchanged. Ni/Al will lower the total cost of ownership by reducing or eliminating field service issues or maintenance schedules regardless of end use environment.


 

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Typical Elastomers-Galvanic Compatibility

168 Hour Exposure to Salt Spray / Salt Fog in Accordance with CHO-TM-100

Substrate Filler
Nickel-Plated
Aluminum*
Passivated
Silver-Plated
Aluminum
Silver-Plated
Aluminum
Nickel-Plated
Graphite
Silver-Plated
Copper
Aluminum:
6061-T6 CR6 Finish
Excellent Excellent Excellent / Good Fair Poor
Aluminum:
6061-T6 CR3 Finish
Excellent Excellent Good Fair Poor
Aluminum:
6061-T6 Unplated
No Data Good Fair Fair/Poor Not
Recommended
Stainless Steel:
304SS, 316SS
Excellent Excellent Excellent Excellent No Data
Electroless Nickel
.002” thick
Good Good Good Poor No Data
Magnesium Not
Recommended
Not
Recommended
Not
Recommended
Not
Recommended
Not
Recommended

*Tested via CHO-TM-101

 

 


 

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Typical Elastomers-Galvanic Compatibility
504 Hour Exposure to Salt Spray / Salt Fog in Accordance with CHO-TM-100
Substrate Filler
Nickel-Plated
Aluminum*
Passivated
Silver-Plated
Aluminum
Silver-Plated
Aluminum
Nickel-Plated
Graphite
Silver-Plated
Copper
Aluminum:
6061-T6 CR6 Finish
Excellent Good Fair Poor Not
Recommended
Aluminum:
6061-T6 CR3 Finish
Good Good Fair Poor Not
Recommended

*Tested via CHO-TM-101

 

 


 

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UL 94 V-0 Rated Materials

Chomerics introduced the first conductive elastomer with a UL 94 V-0 rating (UL file number 96ME 17043) with allowable thicknesses down to 0.014 inch (0.356mm). Mated to aluminum, this fully extrudable material is a corrosion-resistant nickel-plated graphite filled silicone with shielding effectiveness equivalent to or greater than other commercial grade gaskets: 95 dB from 50 MHz to 10 GHz. CHO-SEAL 6370, 6371 and 0862 are UL 94 V-0 flammability rated materials. CHO-SEAL 6330 and 6372 are UL 94 V-1 rated.
(For UL certifications, please visit www.ul.com)

 


 

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Lightning Strike Resistance

The survivability of any system to lightning strike is dependent on specific flange design. Lightning strike testing of
CHO-SEAL 1298 gasket material has demonstrated survivability beyond 5 kA/in. Test data is available upon request.
(Request Test Report TR-34A.)

 


 

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Fluid Resistance - Harsh Environments

Table 6 lists a qualitative assessment of fluid resistance by material type. The customer is encouraged to evaluate specific materials to the requirements demanded by the application.

 

 


 

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Fluid Resistance - Common Fluids on Silicone

Table 5 illustrates the change in physical properties of CHO-SEAL S6305 after exposure to a variety of common fluids. The complete report is available from Chomerics upon request.

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Exposure of CHO-SEAL® S6305 to Common Household Fluids Tensile/Elongation in accordance with ASTM D412
Exposure Conditions: 70 hrs @ 22°C/50% RH Pre-Exposure Post-Exposure % Change
Test 1
ClearVue® Tensile [psi] 200 178 -11%
ClearVue® Elongation [%] 289 317 10%
Formula 409® Tensile [psi] 200 197 -2%
Formula 409® Elongation [%] 289 219 -24%
Windex® Tensile [psi] 200 202 1%
Windex® Elongation [%] 289 166 -43%
Test 2
Carpet Cleaner Tensile [psi] 203 207 2%
Carpet Cleaner Elongation [%] 414 443 7%
Coffee Tensile [psi] 203 211 4%
Coffee Elongation [%] 414 439 6%
Cola Tensile [psi] 203 199 -2%
Cola Elongation [%] 414 433 5%
Hairspray Tensile [psi] 203 207 2%
Hairspray Elongation [%] 414 326 -21%
Tire Cleaner Tensile [psi] 203 175 -14%
Tire Cleaner Elongation [%] 414 418 1%
Vinyl Protectant Tensile [psi] 203 172 -15%
Vinyl Protectant Elongation [%] 414 433 5%
Tap Water Tensile [psi] 203 199 -2%
Tap Water Elongation [%] 414 439 6%
Windshield Washer Solvent Tensile [psi] 203 207 2%
Windshield Washer Solvent Elongation [%] 414 418 1%

 

 


 

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Typical Elastomer Fluid Resistance
Exposure / Fluid Type Elastomer Choice
Silicone Fluorosilicone EPDM
High Temp Excellent Good Fair
Low Temp Excellent Excellent Excellent
ASTM 1 Oil Fair/Good Good Poor
Hydraulic Fluids (Phosphate Ester) Poor Poor Poor
Hydrocarbon Fuels Poor Good Excellent
Ozone, Weather Good Good Good
STB (NBC Decontamination Fluid) Poor Fair/Good Good
Dilute Acids Fair Good Good

 

 


 

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Dual Functionality Gaskets, "Co-Extruded and Co-Molded"

Co-Extruded and Co-Molded gaskets (dual gaskets with both a conductive and a non-conductive element, cured in parallel) provide additional environmental sealing and corrosion protection. Seam vulcanization ensures the long term integrity and stability of the gasket.

Co-Extruded and Co-Molded gaskets permit the cost effective use of existing flange designs, while offering attachment alternatives via the less expensive, non-conductive material. Compared to bonding and mounting separate gaskets or double-groove designs, Co-Extruded and Co-Molded gaskets offer design, cost and handling advantages.

 

NOTICE: The information contained herein is to the best of our knowledge true and accurate. However, since the varied conditions of potential use are beyond our control, all recommendations or suggestions are presented without guarantee or responsibility on our part and users should make their own tests to determine the suitability of our products in any specific situation. This product is sold without warranty either expressed or implied, of fitness for a particular purpose or otherwise, except that this product shall be of standard quality, and except to the extent otherwise stated Chomerics’ invoice, quotation, or order acknowledgement. We disclaim any and liability incurred in connection with the use of information contained herein, or otherwise. All risks of such are assumed by the user. Furthermore, nothing contained herein shall be construed as a recommendation to use any process or to manufacture or to use any product in conflict with existing or future patents covering any product or material or its use.