Custom Electronics EMI Shielding & Grounding Gaskets

No material is compliant on its own, and no honest supplier will claim otherwise: FCC Part 15 (US unintentional radiators) and CISPR 32 / EN 55032 (multimedia equipment emissions) are evaluated on the tested device, so the compliance result belongs to the equipment. What the materials on this page carry is their own documentation: volume resistivity, a coupon shielding-effectiveness figure per the MIL-DTL-83528 method, a UL 94 class where rated, and lot-code traceability.

They support designs evaluated to the emissions limits; H-O supplies the converted parts and the paperwork, and the device team owns the EMC test. [4]

By the joint. Fabric-over-foam (and conductive silicone sponge) is the low-closure-force gasket for light plastic lids and long serviceable seams, with typical SE around 70–100 dB per the maker TDS. A MIL-DTL-83528 conductive elastomer is the choice where the joint can supply real closure force and you want the highest, most repeatable SE, with the Type set by galvanic match.

Conductive foil tape is not a gasket at all; it bridges seams and terminates cable shields. And a ground-contact pad or strip is the discrete PCB-to-chassis bond. The form-factor checklist builder on this page assembles the set. [2]

MIL-DTL-83528 covers conductive elastomer types by filler chemistry: Type A (silver-copper), Type B (silver-aluminum), Type C (silver-glass), Type D (silver-nickel), and Type M (nickel-graphite), each with its own maximum volume resistivity and coupon SE. Type A silver-copper is the highest-conductivity register (capable of roughly 110 dB plane-wave SE at 10 GHz on a QPL grade TDS, about -55 to +160 °C), but it corrodes on bare aluminum.

Type M nickel-graphite is the cost-effective, aluminum-tolerant workhorse. Pick the Type by galvanic compatibility with your housing metal first, then by the SE the band needs; specify the Type on the callout. [2]

Galvanic corrosion. Silver and copper sit far from aluminum on the galvanic series, so a silver-copper-filled gasket against a bare-aluminum housing forms an aggressive galvanic couple. In humidity and salt-fog it corrodes, contact resistance at the seam climbs, and shielding effectiveness degrades over months in the field, even though it tested fine at build.

Use the aluminum-tolerant chemistries (nickel-graphite Type M, nickel-aluminum) on aluminum housings, keep silver-copper on tin, copper, brass, and stainless, and verify the pairing by salt-spray per ASTM B117.

The galvanic look-up tool on this page returns the verdict for each combination. [7]

Because enclosures leak at their apertures and seams, not through the metal. Any unbridged opening — a connector cut-out, an unused port, a seam that contacts only intermittently — behaves as a slot antenna once its longest dimension nears a half wavelength, and SE collapses at that frequency. The design rule is to keep every gasket, clip, and fastener contact pitch below one twentieth of a wavelength at the highest frequency of concern, so the boundary reads as one continuous bond rather than a row of slots.

Gaskets and foil-tape bridges are the parts that make that pitch real. [3]

Not through a single long trace, which is inductive at RF and lets the can radiate. Give the shield a continuous perimeter ground pad (roughly 0.5–1.0 mm wide) around its footprint, with via stitching (roughly every 1.5–2 mm) tying it to the internal ground plane, then make the board-to-chassis bond short and wide with a conductive-elastomer ground-contact pad or a foil / fingerstock-style strip.

Where the pad sits next to live traces, add a Kapton® or Nomex® dielectric window. H-O converts the contact pad, the strip, and the dielectric layer; the pad width and via pitch are board-layout guidance. [6]

A low-closure-force gasket: conductive silicone sponge (BISCO® EC-2130) or fabric-over-foam. A rigid conductive elastomer needs real compression force to make continuous contact; on a snap-fit plastic lid that cannot supply it, the lid bows and contact goes intermittent, and the assembled SE comes out worse than a soft gasket would have delivered. Match the gasket's compression class to the closure force the housing actually supplies, and reserve the firm conductive elastomers for metal housings and bolted board-level shields.

No. A gasket's SE figure is a coupon comparison value measured by a standard method (the MIL-DTL-83528 coupon method, or an enclosure method such as IEEE Std 299), and it tells you how one material compares to another. Your device's real SE depends on every aperture, seam, and ground point around the gasket, so a high-SE gasket on a leaky housing still fails.

Specify the material's coupon SE and volume resistivity per TDS on the callout, design the seams and grounds, and cite the emissions limit (FCC Part 15, CISPR 32) by designation; the compliance result belongs to the tested device. [3]

Often, yes, when the desense is self-interference. A switching regulator or high-speed digital section inches from the radio raises the receiver's noise floor with broadband hash, and no antenna tuning recovers the lost link budget. A board-level shield can over the aggressor section — a small Faraday cage that is gasketed to close its seams and grounded to the chassis on a low-impedance path — keeps that noise off the antenna's band.

The shielding job is the same continuous-bond and grounding problem covered elsewhere on this page, applied to protect a receiver rather than to pass an emissions scan.

Yes: copper and aluminum conductive foil tapes with conductive adhesive, slit to width and to length for seam bridging and cable-shield termination. The performance variable is the through-tape contact: the conductive adhesive and the bonded interface set the DC resistance across the joint, not the foil substrate, so surface prep, dwell, and pressure matter. We validate the tape and adhesive against the substrate, surface energy, temperature, exposure, dwell, pressure, prep, and part geometry and assembly method; send those with the drawing.

Yes: perimeter gaskets, aperture-frame gaskets, ground-contact pads, dielectric windows, and foil-tape pieces can ship as a kitted set, one kit per device, parts on liner in assembly order, with lot-code TDS records per material. That is exactly the documentation an EMC review and a production line want to see, and it removes the field-trimming that starts most aperture and seam leaks.

By part: for seam gaskets, the seam geometry, gap, closure force available, target frequency band, and housing metal and finish; for ground-contact pads, the contact footprint, the gap to the chassis, and whether a dielectric isolation layer is needed; for foil tape, the seam or termination geometry and the substrate; and for any part, the flame, chemical, or outdoor requirement.

Plus quantities for prototype and production, and the standards language you need on the paperwork (material properties per TDS; emissions limits by designation). "Recommend the set" is a valid callout: that is what the engineering review is for.