EMI Gaskets / EMI Shielding Gaskets
Stockwell Elastomerics manufactures custom EMI gaskets, EMI RFI gaskets, EMI shielding gaskets and other gaskets from various EMI shielding materials to specification.
The ever growing wireless and electronics markets have increased the stakes for managing electromagnetic interference (EMI). This holds true for consumer, commercial/industrial markets as well as military applications. Managing EMI is required of electronic device manufactures under Title 47 of the Federal Code of Regulation and Mil-DTL-461. These are some leading EMI standards and their applications:
- Title 47 CFR Part 15 - Radio frequency (RF) devices
- Title 47 CFR Part 18 - Industrial, scientific & medical equipment
- Title 47 CFR Part 68 - Telecommunications
- Mil-STD-461 - Control of EMI for subsystems and equipment
- Mil-DTL-83528 - (Related) gasket material for EMI/RFI
EMI Management with Gaskets
Radiant EMI is often emitted by unintended antennas; meaning internal wires and components can act as emitting antennas. A common practice to manage EMI radiation and EMI susceptibility is to completely encase electronics in a conductive enclosure. This usually entails a housing, lid, and a conductive gasket; it's critical that the lid and enclosure have complete contact all the way around, hence a conductive gasket. Stockwell Elastomerics manufactures EMI gaskets for Class A (typically industrial), Class B (typically residential), and military applications. Stockwell EMI gaskets regularly perform EMI attenuation as well as environmental sealing (rain, dust, wash down, etc.)
EMI Gasket Manufacturing
Stockwell Elastomerics offers manufacturing for all of these types of EMI gaskets:
- Waterjet Cut EMI Gasket
- Molded EMI Gasket
- Wire Mesh / Sponge EMI Gasket
- Conductive Adhesive Backed EMI Gasket
Class A & Class B EMI Gaskets Materials
Nickel / graphite filled silicone gasket materials are predominantly specified for industrial, commercial and residential applications because of their good attenuation, strong sealing properties and low cost. Most commercial EMI gasket applications can be satisfied with Ni/C products. Larger enclosures may require thicker and softer EMI gaskets (see Combination Silicone Sponge and Wire Mesh EMI Shielding Gaskets)
Common EMI Rubber Materials (Class A and Class B)
- SNE-540 - Nickel / Graphite Filled Silicone (45 durometer)
- EC-2130 - Nickel / Graphite Filled Silicone (30 durometer)
- SNEF-60 - Nickel / Graphite Filled Fluorosilicone (60 durometer)
Military & Aerospace EMI Materials
Mil-STD-461 is the global specification related to EMI for equipment and subsystems. MIL-G-83528C is the specification for filled EMI gaskets. This requirement is very concise - if a print calls for a MIL-G-83528C Type X gasket, the polymer, fill, attenuation, and mechanical properties are specified. The most common military / aerospace EMI gaskets often call for silver coated aluminum to meet MIL-G-83528C specifications. Military or aerospace applications may also use fluorosilicone instead of silicone for its fuel and chemical resistance.
Common Mil-G-83528C Fill and Polymer
- Type A = Silver coated Copper - Silicone (65 Durometer)
- Type B = Silver coated Aluminum - Silicone (65 Durometer)
- Type C = Silver coated Copper - Fluorosilicone (75 Durometer)
- Type D = Silver coated Aluminum - Fluorosilicone (70 Durometer)
- Type M = Silver coated Glass - Silicone (65 Durometer)
Combination Silicone Sponge and Wire Mesh EMI Shielding Gaskets
Large EMI gaskets for electrical enclosures and cabinets are often addressed using a corrosion resistant Monel wire mesh bonded to a closed cell silicone sponge. The wire mesh / sponge gasket allows for greater tolerances between sealing faces. The sponge and wire mesh offer forgiving, low closure forces to prevent sheet metal bowing between latches or fasteners.
- Closed Cell Silicone - Common thicknesses are .125" and .250". Closed cell silicone sponge R10470-M and medium density silicone foam HT-800 are most frequently specified for the environmental gaskets. Gaskets are normally supplied with a high strength pressure sensitive acrylic adhesive.
- Monel Mesh - .125" x .125" wide and .250" x .125" wide Monel mesh is bonded to the inside or outside gasket edge to provide a relatively low cost and reliable EMI shielding gasket with long term weather sealing. The Monel mesh is constructed from woven .0045" wire that meets QQ-N-281.
- Aluminum mesh (AMS 4182) or tin plated copper clad steel wire (ASTM B520) are available on special order.
Waterjet EMI Gaskets & Prototype EMI Gaskets
In-house water jet cutting and stock materials allow Stockwell Elastomerics to quickly supply production and prototype EMI gaskets. 2D EMI gaskets may be prototyped on Stockwell Elastomerics' waterjet cutting machines and then moved to molding or production parts, all using the same EMI compound.
Molded EMI Shielding Gaskets
Stockwell Elastomerics compression molds conductive silicone and fluorosilicone rubber compounds in its custom molding facility. Molding the EMI gasket allows the designer to add sealing ribs and other performance enhancing features to optimize environmental sealing and EMI shielding properties. Stockwell Elastomerics has a broad range of compounds that meet MIL-G-83528B classifications for electrically conductive EMI shielding gaskets.
Contact Stockwell Elastomerics for EMI Gaskets
Contact Us for further assistance with EMI gaskets, EMI/RFI shielding gaskets, military EMI gaskets, combination silicone sponge - wire mesh EMI shielding gaskets, waterjet cut and molded EMI gaskets.