EMI shielding gaskets
EMI gaskets: conductive shielding gaskets, cut to your drawing or supplied to order
An EMI gasket, also sold as an RFI or EMI/RFI shielding gasket, is a conductive gasket that closes the seam between a housing and its cover, so the enclosure stays one continuous shield and radio-frequency energy cannot leak through the joint [S9]. A conductive elastomer gasket, silicone or fluorosilicone rubber filled with silver-plated or nickel-plated particles, also seals the same joint against water and dust [S11][S13]. Conquest Seal waterjet-cuts flat EMI gaskets from conductive silicone and fluorosilicone sheet to your drawing, and supplies conductive O-rings, molded shapes and extruded profiles from their manufacturers. A certificate of conformance ships with every order, and a person replies to a quote request within one business day.
- Cut to your drawing
- Flat gaskets from conductive silicone and fluorosilicone sheet, on Conquest Seal's own waterjet
- Supplied to order
- Conductive O-rings, molded shapes, extruded profiles and spliced rings, from their manufacturers
- Fillers
- Silver-plated copper, silver-plated aluminum, silver, silver-plated glass, silver-plated nickel, nickel-plated graphite and nickel-plated aluminum [S9][S15]
- Binders
- Silicone, fluorosilicone and EPDM [S15]
- Military specification
- MIL-DTL-83528; when your drawing calls it out, the material comes from a manufacturer on QPL-83528 [S1][S2]
- Paperwork
- Certificate of conformance with every order
- Quote reply
- A person replies within one business day
Filler, binder and specification rows cite the sources below; the compound datasheet and your drawing govern the final choice.
What an EMI gasket does
Every cover, door or bolted panel leaves a seam in a shielded enclosure, and a seam that does not conduct lets radio-frequency energy in or out [S9]. A conductive gasket conforms to both flange faces and carries current across the joint, so the enclosure behaves as one shield again [S9]. EMI, RFI and EMI/RFI shielding gaskets are the same parts under different names; a grounding gasket is a related part, judged by its contact resistance rather than by a shielding figure. The what is an EMI gasket guide covers when an enclosure needs one and how EMI, RFI and EMC differ.
EMI gasket forms, and when each is used
The table sets the common forms side by side: what the sources use each one for, whether it also seals the joint, and where Conquest Seal comes in [S9][S17]. It is qualitative; the shielding bands, deflection windows and relative cost of each form are on the EMI gasket types guide.
| Form | Used for, in the sources | Also seals the joint | Conquest Seal | Source |
|---|---|---|---|---|
| Flat gasket cut from conductive sheet | Flat covers and flanges held by bolts, with no groove; a flat gasket takes only a small deflection | Yes, with bolts through close-fitting holes or a seal under each bolt head | Waterjet-cuts it to your drawing; see conductive silicone sheet | [S9] |
| Molded O-ring, D-ring or shaped gasket | A groove that sets the deflection, where the joint must seal pressure or fluid; connector flanges and waveguide joints | Yes, in a groove | Supplied from the manufacturer; see conductive O-rings | [S3][S9] |
| Extruded profile or spliced ring: solid or hollow O, D, P, rectangle or channel | Long seams, doors and large frames; hollow sections where the flange gap is uneven or the closing force is low | Yes | Supplied from the manufacturer, cut to length or spliced into a ring | [S9] |
| Form-in-place bead | Thin flanges and complex paths on a housing that can take the cure; dispensed by robot and cured in place | Partly: it adheres to the housing, limited by the bead size | Dispensed on your housing by its maker; compared on the types guide | [S9][S37] |
| Knitted wire mesh | Shielding alone with metal-to-metal contact, including EMP and high-current joints | No, unless it has an elastomer core, which gives a limited dust seal | Compared on the types guide | [S9][S34] |
| Beryllium-copper fingerstock | Doors and panels that open often, with a wiping contact | No | Compared on the types guide | [S17][S35] |
| Conductive foam or fabric-over-foam | Low closing force on indoor commercial joints | Dust only | Compared on the types guide | [S17][S36] |
| Oriented wire in silicone | A sheet that shields and seals in one part, at a relatively high closing pressure | Yes | Compared on the types guide | [S17][S38] |
Fillers, and when each is used
The filler sets the conductivity, the shielding figure and how the gasket behaves against the flange metal; the binder sets the fluid resistance and, with the filler, the temperature limits [S10][S15]. The table is qualitative; volume resistivity, shielding and hardness by filler are on the conductive elastomers page.
| Filler | Used for, in the sources | MIL-DTL-83528 type letters | Source |
|---|---|---|---|
| Silver-plated copper | The highest shielding in the maker tables, on dry or protected flanges; poor corrosion resistance against aluminum | A, G and K in silicone; C in fluorosilicone | [S9][S14][S15] |
| Silver-plated aluminum | Aluminum flanges, salt fog and outdoor enclosures | B in silicone; D in fluorosilicone | [S9][S14][S15] |
| Silver | The lowest volume resistivity in the maker tables | E and J in silicone; F in fluorosilicone | [S9][S10][S11] |
| Silver-plated glass | Lighter, lower-cost parts for commercial enclosures | M | [S10][S11][S14] |
| Silver-plated nickel | Harder grades and non-silicone binders | L | [S9][S11] |
| Nickel-plated graphite | The common commercial filler: shielding at lower cost, with fair corrosion resistance against aluminum | None in the maker tables | [S9][S11][S15] |
| Nickel-plated aluminum | Aluminum flanges at lower cost than silver-plated aluminum; not suited to grounding or lightning-strike paths | None in the maker tables | [S15] |
| Carbon | Grounding and low-level shielding | None in the maker tables | [S9][S10] |
Silver-plated aluminum and nickel-plated aluminum are the fillers the sources pair with aluminum flanges; the galvanic compatibility chart gives the pairing by flange finish [S9][S15].
Conductive silicone or conductive fluorosilicone
The fillers are the same in both, so the binder is the difference. Fluorosilicone resists the fuels, oils and solvents that swell silicone, at a higher cost and over a narrower temperature range, and its MIL-DTL-83528 types pass the specification's fluid immersion test [S14][S15]. The side-by-side comparison is on the conductive elastomers page.
MIL-DTL-83528 and the QPL
MIL-DTL-83528 is the Department of Defense specification for conductive elastomer shielding gaskets, and Revision J with Supplement 1 is the active issue on DLA ASSIST [S1]. A type letter names the filler and binder, a slash sheet names the part shape and a dash number names the size, so M83528/001A001 is a Type A round strip, size 001, from sheet /1 [S2][S3]. The MIL-DTL-83528 guide reads a callout letter by letter.
When your drawing calls out MIL-DTL-83528, the sheet, the molded part or the extrusion comes from a manufacturer listed on QPL-83528, and the quote names that manufacturer [S2]. A qualified products list names manufacturers, not distributors, and Conquest Seal is not on it; check the list on the DLA Qualified Products Database on the day you specify, because listings change [S2].
What to send for a quote
Seven items let the quote come back without a second round of questions.
- The form: a flat gasket drawing as a DXF, DWG or PDF, an O-ring dash number or its ID and cross-section, or an extruded profile with its free height and width.
- The filler and binder, or the MIL-DTL-83528 type letter and sheet your drawing names.
- The sheet thickness for a flat gasket, and the hardness if the drawing names one.
- The flange metal and its finish.
- The environment: temperature range, fuels or cleaning agents, salt fog or weather.
- Adhesive backing yes or no, and whether it must conduct.
- The quantity and the paperwork the order needs.
Send them through request a quote and a person replies within one business day. A certificate of conformance ships with every order, naming the part number, the specification, the manufacturer, the lot, the quantity and the manufacturer's cure date. Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
Every EMI page, by the question it answers
Each page below answers one question in depth; this page is the overview.
| Question | Page |
|---|---|
| What is an EMI gasket, and how do EMI, RFI and EMC differ? | What is an EMI gasket? |
| Which type suits the joint: elastomer, mesh, foam, fingerstock or form-in-place? | Types of EMI gaskets compared |
| Which filler and binder, and what do the makers publish for each? | Conductive elastomers |
| How is a flat conductive gasket cut to a drawing? | Conductive silicone and fluorosilicone sheet and the cutting guide |
| How are conductive O-rings sized and supplied? | Conductive O-rings |
| How deep is the groove, and how far must the gasket deflect? | Groove design and deflection |
| Which filler goes on which flange finish? | Galvanic compatibility chart |
| What does a shielding figure in dB mean, and how is it tested? | Shielding effectiveness testing |
| Why did a gasket that shielded stop shielding? | EMI gasket failure modes |
| How do I read a MIL-DTL-83528 callout? | MIL-DTL-83528 explained |
| Can the gasket carry an adhesive backing? | EMI gaskets with adhesive backing |
| What seals and gaskets does a connector maker buy? | Connector seals and EMI gaskets |
Frequently asked questions
What is an EMI gasket?
A conductive gasket that closes the seam between a housing and its cover, so the enclosure stays electrically continuous and radio-frequency energy cannot leak through the joint [S9]. A conductive elastomer gasket also seals the joint against water and dust [S13].
Are EMI gaskets, RFI gaskets and conductive gaskets the same thing?
Yes: in the gasket trade, EMI, RFI and EMI/RFI shielding gaskets name the same conductive parts. A grounding gasket also conducts, but it bonds two parts at a point or over a small area, and it is judged by its contact resistance rather than by a shielding figure.
What are EMI gaskets made of?
A conductive elastomer gasket is a silicone, fluorosilicone or EPDM binder filled with silver-plated copper, silver-plated aluminum, silver, nickel-plated graphite or another conductive particle [S10][S15]. The other forms use metal or metal-plated parts: knitted wire mesh, beryllium-copper fingerstock, plated foam and oriented wire in silicone [S9][S17].
Can Conquest Seal cut an EMI gasket to my drawing?
Yes, for flat gaskets: Conquest Seal waterjet-cuts conductive silicone and fluorosilicone sheet to your drawing. Conductive O-rings, molded shapes and extruded profiles are supplied from their manufacturers, and a certificate of conformance ships with every order.
What happens when my drawing calls out MIL-DTL-83528?
The sheet, the molded part or the extrusion comes from a manufacturer listed on QPL-83528, and the quote names that manufacturer [S2]. A qualified products list names manufacturers, not distributors, so Conquest Seal is not on it; the list itself is on the DLA Qualified Products Database [S2].
Conductive silicone or conductive fluorosilicone: where is each used?
Silicone is the general-purpose binder; fluorosilicone is used where fuels, oils or solvents can reach the joint, because it resists them where silicone swells [S14][S15]. The fillers are the same in both, and the makers describe fluorosilicone as the higher-cost binder with the narrower temperature range [S15].
What should I send to get an EMI gasket quoted?
The drawing or profile, the filler and binder or the MIL-DTL-83528 type letter, the sheet thickness or size, the flange metal and finish, the environment, adhesive backing yes or no, and the quantity with the paperwork the order needs. A person replies to a quote request within one business day.
Sources
- [S1] DLA ASSIST QuickSearch, document details for MIL-DTL-83528 (ident 34009): Revision J with Supplement 1, active, 11 October 2023 - https://quicksearch.dla.mil/qsDocDetails.aspx?ident_number=34009 - accessed 2026-09-25
- [S2] DLA Qualified Products Database, QPL-83528 parts search - https://qpldocs.dla.mil/search/parts.aspx?qpl=1785 - accessed 2026-09-25
- [S3] DLA ASSIST, MIL-DTL-83528E Supplement 1 (13 August 2012), list of specification sheets - https://quicksearch.dla.mil/WMX/Default.aspx?token=5716692 - accessed 2026-09-25
- [S9] Parker Chomerics®, EMI Shielding Engineering Handbook, November 2000 edition - accessed 2026-09-25
- [S10] Laird®, Elastomeric EMI Shielding Solutions: ElectroSeal™ conductive elastomer catalog (EMI-CAT-ECE) - https://www.laird.com/sites/default/files/2019-09/EMI-CAT-ECE%20080615%20EletroSeal.pdf - accessed 2026-09-25
- [S11] Laird, EMI Essentials: Introduction to Electrically Conductive Elastomers, material selection tables and case study - accessed 2026-09-25
- [S13] Laird, Electrically Conductive Elastomers (ECE) product family page - https://www.laird.com/products/enclosure-level-emi-shielding/electrically-conductive-elastomers-ece - accessed 2026-09-25
- [S14] 3G Shielding Specialties, Waveseal® conductive elastomer sheet stock datasheet (MIL-DTL-83528D type limits per material) - https://www.3gshielding.com/docs/3GSS%20Conductive%20Elastomer.pdf - accessed 2026-09-25
- [S15] Parker Chomerics, Conductive Elastomer Selection Guide, CHOC1029, June 2026 (the material guidelines table, form factors, test notes A to H; distributor copy) - https://www.hitek-ltd.co.uk/wp-content/uploads/CH5434-TDS.pdf - accessed 2026-09-25
- [S17] Tech-Etch, EMI/RFI Shielding Product Guide (fingerstock, fabric-over-foam, conductive foam, oriented wire) - https://techetch.com/wp-content/uploads/2021/01/Tech-Etch_Design_Guide_1-12_8P.pdf - accessed 2026-09-27
- [S34] TE Connectivity, Knitted Wire Mesh EMI gaskets - https://www.te.com/en/products/emi-and-emc-solutions/emi-shielding/emi-gaskets/intersection/knitted-wire-mesh.html - accessed 2026-09-27
- [S35] TE Connectivity, Beryllium Copper Fingers - https://www.te.com/en/products/emi-and-emc-solutions/emi-shielding/resources/beryllium-copper-fingers.html - accessed 2026-09-27
- [S36] TE Connectivity, Conductive Foam for EMI Gaskets - https://www.te.com/en/products/emi-and-emc-solutions/emi-shielding/conductive-elastomers/resources/conductive-foam.html - accessed 2026-09-27
- [S37] TE Connectivity, Form in Place Gasket, EMI Shielding - https://www.te.com/en/products/emi-and-emc-solutions/emi-shielding/resources/form-in-place-gasket.html - accessed 2026-09-27
- [S38] TE Connectivity, How Oriented Wire Improves EMI Shielding in Electronic Devices - https://www.te.com/en/products/emi-and-emc-solutions/emi-shielding/oriented-wire.html - accessed 2026-09-27
Chomerics is a trademark of Parker Intangibles LLC, a Parker Hannifin company; Laird is a trademark of Laird Technologies, Inc., an affiliate of Qnity Electronics, Inc.; ElectroSeal is a trademark of an affiliate of Qnity Electronics, Inc.; Waveseal is a trademark of 3Gmetalworx Inc. Tech-Etch, TE Connectivity and 3G Shielding Specialties are named as the makers of their own products. No affiliation or endorsement is implied.
Reviewed by Grant Midstokke, Conquest Seal Corporation. Last updated . Statements on this page are drawn from the sources listed above; the compound datasheet and your drawing govern the final choice.
Send the EMI gasket drawing, the filler and the quantity
A DXF, DWG or PDF for a flat gasket, a dash number for an O-ring or a profile for an extrusion; the filler or MIL-DTL-83528 type letter, the flange metal, the environment and the quantity. A person replies within one business day.
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