Particle-filled silicones provide environmental sealing, electrical conductivity, and resistance to electromagnetic interference (EMI) and/or radio frequency interference (RFI). These conductive shielding elastomers are filled with metal or metal-coated particles, and are supplied as sheets, rolls, or ready-to-mold compounds for the cost-effective fabrication of silicone shielding gaskets.
Engineers use particle-filled silicones in numerous shielding and sealing applications, but can these conductive elastomers overcome industry-wide problems such as brittleness and low tear strength? Historically, filling an elastomer with metal particles meant imparting conductivity and shielding at the expense of flexibility and strength. What’s changed since then?
SpecShield and ArmouRFI
Specialty Silicone Products (SSP) has developed a line of EMI and RFI shielding silicones that aren’t too hard, aren’t too brittle, and aren’t too expensive. SpecShield silicones include silver-filled products, but SSP also offers cost-effective alternatives with nickel-graphite particles that provide silver-like conductivity. For applications that require exceptional tear strength, there’s ArmouRFI.
ArmouRFI is a strong and important part of the SpecShield family. Filled with nickel-coated graphite particles, ArmouRFI is reinforced with an internal nickel-coated mesh. This increases the electrical conductivity and physical strength for this 65-durometer material (also available in 30 and 40 Shore A), and also yields volume resistivity values that are similar to significantly more expensive shielding elastomers with silver-coated metal fills.
Product Data and Shielding Performance
This table contains product data for ArmouRFI (SSP-502-65-032-Composite-NG-1). All data was obtained using ASTM test method, and is available for download via the SSP website.
Data | Typical Values |
Shore A (58 – 68 range) | 65 |
Tensile psi | 950 |
Elongation % | 20 |
Tear “B” ppi (35 min) | 165 |
Specific Gravity | 1.93 |
Thickness (0.029 – 0.035 inches) | 0.032 inches |
Volume Resistivity ohm/cm | 0.007 ohm/cm |
Compression Set % (70 hrs at 100° C) | 25 |
Color | Dark Gray |
Thermal Stability Range | -55° to 200° |
How ArmouRFI Solves Shielding Challenges
RFI gaskets that are too brittle or that tear easily can result in RFI leakage that damages electronic devices or interferes with their operation. Compared to other shielding materials, ArmouRFI provides outstanding tear strength and impressive tensile strength. This latter specification is especially important. If a material lacks sufficient tensile strength, tearing of the shielding gasket can occur during fabrication or use.
SSP supplies ArmouRFI in continuous rolls up to 15-inches wide for the efficient and cost-effective fabrication of RFI shielding gaskets. Compared to molded sheets, continuous rolls promote optimum yields. Continuous rolls also support the use of automated equipment instead of time-consuming manual operations. For more information, watch the video below and contact SSP.
