Medical Imaging Insulation, Flex Circuit & EMI Shielding

They do opposite electrical jobs even though they can be the same shape. A dielectric insulator blocks current and isolates one conductor or component from another; it is a non-conductive film, typically polyimide, chosen for dielectric strength. An EMI or RFI shielding gasket carries current across a seam to ground so electromagnetic interference stays out of (or in of) the electronics; it is a conductive part, a conductive elastomer, foil, or sponge, chosen for conductivity.

Insulate versus conduct is the single most important decision on this page, because a conductive part placed where a dielectric was needed shorts the circuit, and a dielectric placed where a shield was needed leaves the seam floating and the shielding ineffective. Name the electrical role on the drawing for every part and keep the two clearly separate, especially when an imaging module needs both.

Dielectric strength is reported per ASTM D149; conductivity is a maker-TDS property.

Match the film thickness to the working voltage with a safety margin, because dielectric strength is rated per unit thickness, so a thicker film withstands more voltage. A high-dielectric-strength grade such as a polyimide film also holds its properties at the elevated temperature near a detector or heat source, which a lower-temperature film would not.

The practical approach is to take the working voltage, apply the margin your design rules require, and select the gauge whose rated dielectric strength clears that with margin, then confirm the value against the maker TDS for the specific grade.

Where the insulator is laminated into a stack, confirm the dielectric of the whole stack, not just one layer. State the working voltage and the thermal environment on the drawing so H-O can match the right grade and gauge. Dielectric strength is reported per ASTM D149; grade values are per the TDS on file.

Match the conductive form to the joint and the closure force. Use a conductive EMI elastomer for a clamped enclosure seam where the enclosure provides closure force, since it conforms and gives a durable conductive gasket. Use a conductive foil tape to shield a flat surface, wrap a cable or harness, or bond a conductive seam, where a thin conductive layer rather than a gasket is wanted, and use a conductive adhesive so the ground path runs through the bond.

Use a soft conductive solid silicone where the closure force is light and a stiff elastomer would not compress, for example a snap or lightly latched seam, since it shields and seals under low force. The shielding result belongs to the assembled enclosure, the gasket plus the seam geometry plus the closure, so confirm the conductivity and the shielding behavior for the application on the maker TDS.

Tell H-O the joint, the closure force, and whether the part must also seal.

Yes. H-O a coverlay-style dielectric to the coverlay openings and the circuit outline, and laminates a bondable FEP-coated polyimide into the flex stack where the insulator must bond rather than sit free. The FEP coating heat-seals the polyimide into the assembly while the polyimide base keeps the dielectric strength and thermal stability through soldering and service. For a stiffener, H-O a general-purpose polyimide to the connector or component area to add local rigidity.

Tell H-O the coverlay opening pattern, the stiffener outline, the film grade and gauge, and the lamination requirement, and supply the circuit drawing. The fine-feature die-cutting and lamination are standard converting operations; dielectric strength is reported per ASTM D149 and grades are referenced to the relevant designations by the material maker where the flex is handled.

The usual cause is a broken conductive path. An EMI gasket only shields if it carries current continuously across the seam to ground, so the path opens if the closure force cannot compress the gasket, if a conductive foil was applied with a non-conductive adhesive, or if the seam geometry leaves a gap the gasket cannot bridge.

The fix is to confirm three things: the conductive form matches the joint (a conformable elastomer or a soft soft conductive solid for the available closure force), the closure force actually compresses the gasket for a continuous path, and any adhesive in the ground path is conductive.

Because the shielding result belongs to the assembled enclosure rather than the gasket alone, also check the seam continuity and the grounding of the enclosure. H-O supplies the converted conductive gasket or foil to your drawing; the conductivity is a maker-TDS property and the shielding effectiveness is verified on the assembled enclosure by the device maker.

A microcellular polyurethane such as PORON is the usual choice. It gives controlled soft force-deflection at low stress, so it cushions the board without over-stressing it, low compression set, so it keeps its protection over service life, and a thin profile that fits between a board and a cover while taking up tolerance. For a cushion that sees higher temperature or a sterilization cycle, a soft silicone foam is the alternative, and where the cushion must also insulate and stay thermally stable, a polyimide foam works.

The keys are choosing a grade whose force-deflection matches the board (too firm transmits shock, too soft bottoms out) and sizing the gauge to the standoff so it cushions without bottoming. State the gap, the protection job, and the environment on the drawing. Foam properties are characterized per ASTM D3574; grades are referenced to the medical designations where the cushion is contact-adjacent.

It depends on where the part sits. A purely internal insulator, shield, or cushion with no patient or fluid contact usually does not carry a biocompatibility requirement, but a part on a handled surface, near a fluid path, or in a portable device may. The deciding inputs are the contact type and duration, which determine whether and which ISO 10993 endpoints apply, whether a USP Class VI designation is wanted, or whether an FDA composition basis is enough.

Where a contact basis applies, H-O references a grade whose maker evaluates it against the framework, for example a PORON Medical cushion or a medical silicone where the part is contact-adjacent, and assembles documentation aligned to your requirements. The material maker evaluates the grade at the material level; the device maker owns the finished-device biocompatibility and regulatory file. State the contact basis on the drawing so the right grade ships.

ISO 10993-1 sets the contact classification.

Where the ground path runs through the adhesive, yes. A conductive foil or gasket that relies on its adhesive to complete the circuit to ground needs a conductive adhesive, because a standard pressure-sensitive adhesive is an insulator and would open the ground path at the bond line. Where the conductive part is mechanically clamped so the ground path is metal-to-metal or gasket-to-frame under closure force, the adhesive only needs to hold the part in place and can be standard.

So the question is whether the adhesive carries current: if it does, specify a conductive adhesive; if the clamp carries the current, a standard adhesive that positions the part is fine. A dielectric part, by contrast, always uses a standard (insulating) adhesive. Tell H-O whether the ground path runs through the adhesive, and H-O laminates the right conductive or standard adhesive and kiss-cuts the part on liner to your drawing.

Yes. Precision die-cutting of polyimide and dielectric films into fine features, light-mask windows, slots, insulator washers, and registered openings, is a core H-O capability, using rotary and flatbed die-cutting and, for the smallest features or tight tolerances, laser cutting. The part registers to the optics or the circuit features per your drawing, and H-O holds the gauge and the feature tolerance to print.

For a multi-layer part, H-O laminates the layers (for example a polyimide film to a foam cushion) and the assembly as one piece. Tell H-O the feature geometry, the tolerance, the film grade and gauge, and whether the part is multi-layer, and supply the drawing. The fine-feature die-cutting, lamination, and kiss-cut-on-liner are standard converting operations; dimensional acceptance is to the drawing with first-article and certificate of conformance on request.

The usual cause is too little dielectric margin for the working voltage and environment. Dielectric strength is rated per unit thickness under controlled conditions, so a film that passes a bench check at room temperature can break down in service when the working voltage, an elevated temperature near a detector, contamination, or a thinned or damaged area combine to exceed the local breakdown threshold.

The fix is to choose a high-dielectric-strength grade such as a polyimide film with margin over the working voltage, account for the thermal environment so the film holds its properties at temperature, and protect the film from thinning or damage during assembly. Where the insulator is laminated, confirm the dielectric of the whole stack. State the working voltage, the environment, and any contamination risk on the drawing so the grade and gauge carry margin.

Dielectric strength is reported per ASTM D149; values are per the TDS on file.

No. H-O Products is a precision converter: it makes the insulation, shielding, and cushioning parts (polyimide insulators, EMI gaskets, conductive foils, PCB cushions) to your drawing from material grades commonly used in medical-device electronics, under an ISO 9001:2015 quality management system. H-O is an ISO 9001:2015 certified organization; that certification governs the converting process, not a device clearance.

H-O does not make finished medical devices and does not claim an ISO 13485 certification, an FDA device registration or clearance, or a cleanroom certification.

Material grades are referenced by designation to ISO 10993, USP Class VI, and FDA composition frameworks at the material level, where the material maker performs the evaluation. The finished-device biocompatibility, the electrical and EMC validation, and the regulatory file belong to the device maker. H-O supplies the converted parts, the material documentation, and lot traceability aligned to your requirements.

Send the part drawing or a sample and five things: the electrical role (insulate, flex-circuit insulate, shield, or cushion), the duty (the working voltage for a dielectric, the joint and closure force for a shield, the protection job and gap for a cushion), where the part sits (internal, handled, or fluid-adjacent), the geometry (the outline, any fine features like windows or slots, the gauge, and any lamination), and whether the part carries an adhesive and whether it must be conductive.

If a contact basis applies, state the ISO 10993 endpoints, the USP Class VI designation, or the FDA composition basis. Add the prototype and annual volume. With that, engineering returns a material family, a converted-part approach, prototype lead time, and the documentation that can be aligned to your requirements. The quote form below has fields for each of these. Samples typically ship in 3 to 5 business days; standard production in about 2 weeks.