Custom Display, PCB & Shock Protection Parts
H-O Products die-cuts and kiss-cuts PORON® microcellular urethane cushions, display perimeter gaskets, board-level shock pads, insulating standoff and spacer washers, flex-cable keep-out parts, and PSA-backed assembly layers — the cushion-and-seal stack that protects the screen and the board inside phones, tablets, handheld scanners, and IoT devices, built to your drawing.
Built for: LCD/OLED display bezel gaskets that double as dust seals, board-level drop and shock pads, PCB standoff and spacer washers, flex/FPC keep-out cushions, and kiss-cut pressure-sensitive-adhesive (PSA) parts for repeatable assembly — supporting device designs evaluated to IEC 60068-2-31, IEC 60068-2-32, and IEC 60068-2-27 at the assembly level.
To protect a screen and board, work from two interfaces. Display: specify an ultra-soft slow-rebound PORON® 4701-series 30-class perimeter gasket — it cushions the panel, seals the display-to-chassis gap against dust and moisture, and damps vibration in one part; thin foam and film layers take up the LCD/OLED stack tolerance. Board: use ShockSeal® 4790-79 impact pads and PORON® 4701-series cushions to limit drop-induced flex, Kapton® or PET washers to insulate and space standoffs, and foam keep-out parts around flex/FPC cables.
The remaining zones and duties are mapped in the When-to-spec list on this page. Values are per the TDS on file.
Assembly-level, by designation (survival belongs to the tested device): IEC 60068-2-31 (rough handling shocks, Test Ec) · IEC 60068-2-32 (free-fall drop) · IEC 60068-2-27 (shock, Test Ea) · MIL-STD-883 Method 2002 (board mechanical shock) · IEC 60529 (IP ingress code). Material-level, per the maker TDS: ASTM D3574 (flexible cellular methods: density, IFD, CFD, compression set) · ASTM D2240 (durometer) · UL 94 (flammability classes, incl. V-0 on rated grades).
- Display bezel cushion + dust seal: PORON® 4701-series 30-class
- Board-level drop / impact pad: ShockSeal® 4790-79
- General cushion + higher closure force: PORON® 4701 series
- Temperature / flame-class cushion: silicone foam / BISCO® 7xxx
- Standoff / spacer washer: Kapton® / PET film washer
- Economical cushion: PU foam / crosslinked PE
- Assembly placement: kiss-cut PSA + liner + pull tab
This guide is for mechanical and product engineers at electronics and IoT original-equipment manufacturers (OEMs) specifying display gaskets, board-level shock pads, standoff and spacer washers, flex-cable keep-out parts, and kiss-cut PSA assembly layers for phones, tablets, handhelds, wearables, and connected devices — and for the procurement teams qualifying those made-to-order parts.
Display gap / drop requirement → material selection → converted cushion → production supply.
- 1Gap & closure requirementDisplay-to-bezel gap, board deflection budget, and closure force off the drawing.
- 2Select CFD windowPick the compression-force-deflection range and set-resistance grade per ASTM D3574.
- 3Choose material familyPORON® for the default; silicone foam where temperature or flame class governs.
- 4Add PSA / liner / pull tabKiss-cut adhesive and liner so assembly places each part to the drawing.
- 5Die-cut to drawingFlatbed die-cut, kiss-cut, or knife-cut to the display and board outlines.
- 6Quote prototype or productionSample set, then production supply with material traceability and lot-code TDS records.
Where are you in the spec process?
This page serves engineers who already know the cushion or gasket they want and engineers still assembling the stack requirement by requirement. Pick the path that matches where you are; you don't have to read the rest.
Send a drawing, get a quote
A PORON® grade, a display perimeter gasket outline, a board-level shock pad, an insulating standoff washer, or a complete kiss-cut cushion kit on your drawing.
Skip to the quote form →Build the stack requirement by requirement
Six selection factors (compression window, seal, impact, dielectric, keep-out, assembly), a checklist-driven cushion-stack builder, and the material families with TDS-cited methods and by-designation standards language.
Start with selection factors →
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1Send drawingUpload a DXF, STEP, or PDF of the display and board outlines, or describe the device. A sample part works too.
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2Material reviewEngineering reviews the compression window, seal and impact requirements, and dielectric needs against the maker TDSs, and frames the standards language correctly: material classes (UL 94) by TDS, and drop/shock (IEC 60068-2-31, -2-32, -2-27) by designation, with survival belonging to the tested device.
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3PrototypeSamples typically ship in 3–5 business days for common configurations on materials we keep on hand. Made-to-order; MOQ varies by material and part.
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4ProductionStandard production runs ship about 2 weeks after drawing approval, on flatbed die-cutting, CNC knife cutting for kiss-cut pad sets, and kitting for device-level cushion kits. Ongoing parts run with material traceability and lot-code TDS records.
Which interface are you protecting?
Application Zones
Six converted-part problems define display and board protection inside an electronics or IoT device: the display perimeter gasket that cushions and seals the screen; the thin cushion layers inside the LCD/OLED stack; the board-level shock pads that limit drop-induced flex; the insulating standoff and spacer washers that support the PCB; the keep-out cushions that protect flex and FPC cable routing; and the kiss-cut PSA parts that make the whole set placeable in assembly.
Click a tab to see the part, the controlling property, and the families H-O converts for that zone.
Display bezel gasket: one part, three jobs
The display perimeter gasket runs the screen outline between the LCD or OLED module (or the cover lens) and the housing bezel, and it does three things at once: it cushions the panel against the housing as a lid or cover closes and against drop impact; it seals the display-to-chassis gap against dust and moisture; and it damps vibration and resonance carried into the panel from speakers, fans, or haptics.
[11] The default material is an ultra-soft, slow-rebound PORON® microcellular urethane in the 4701-series 30-class range, which conforms at low closure force so it seals without over-loading a thin panel, and holds that force over years because microcellular urethane resists compression set. Where the joint runs hot or needs a flame class, cellular silicone (BISCO® 7xxx / HT series) takes over with UL 94 classes per the grade TDS.
The gasket contributes to the device's dust and moisture exclusion, but the IP rating is earned by the assembled enclosure per IEC 60529, not by the foam alone.
LCD/OLED stack cushioning: taking up the tolerance
Inside the display module, thin foam and film layers sit between the backlight, the LCD or OLED panel, the touch sensor, and the cover lens. Their job is to take up the tolerance stack — the accumulated gap between rigid layers — and to cushion the panel and glass against point loads and flex. On modern "gasketless" OLED designs the cushion increasingly lives inside the stack-up rather than only at the perimeter, so thin PORON® and slow-rebound grades are to the sub-millimeter footprints the module drawing calls for.
The controlling property is the same as everywhere on this page: a compression-force-deflection window the layer holds over life, not a nominal thickness. Film spacers (PET, polyimide) add a rigid, thin shim where the layer must be dimensionally stable rather than compliant.
Board-level shock pads: limiting drop-induced flex
When a device is dropped, the housing decelerates and the board keeps moving, flexing until something stops it. That flex is what fractures brittle solder joints under ball-grid-array (BGA) packages and unseats connectors. Board-level shock pads — PORON® cushions between the PCB and the housing ribs or bosses — take up the free travel and blunt the impact, and the ShockSeal® 4790-79 grade is the dedicated impact-protection material for the highest-energy locations.
The pad is specified by the deflection it must control and the force it must supply across that deflection (per ASTM D3574), not by a nominal thickness. Board mechanical-shock qualification is done at the assembly level to the applicable pulse (IEC 60068-2-27 half-sine, e.g. 50 g / 11 ms, up to MIL-STD-883 Method 2002 severities for rugged devices); the cushions support that design and the survival result belongs to the tested assembly.
Standoff & spacer washers: support and isolate the board
A PCB is supported off the housing on standoffs, and where the board meets each boss there is often a washer doing one or both of two jobs: cushioning the board against the hard boss so a mounting screw does not concentrate stress, and insulating the board from the boss or a metal housing. Compliant washers are from PORON® or foam; dielectric spacer washers are from polyimide (Kapton®) or PET film where the layer must insulate and stay thin.
(Rigid threaded board standoffs are commonly molded UL 94 V-0 nylon — a molded form coordinated through a partner network, not a part; H-O converts the compliant and dielectric washers that sit with them.) Specify the washer's inner and outer diameter, thickness, and whether it insulates, cushions, or both.
Flex-cable keep-out: protect the FPC routing
Flexible printed circuits (FPCs) and flex cables route power and signal between boards, the display, and the battery, and they are fragile: an FPC that abrades against a housing edge or is crushed at a fold fails intermittently, then permanently. Die-cut cushion and keep-out parts protect the routing — a soft PORON® or foam bumper where the flex crosses a hard edge, a thin film liner where it must slide, and a keep-out spacer that holds the flex away from a pinch point.
These are small parts with tight tolerances, so the outline, the keep-out clearance, and any PSA come straight off the routing drawing, not the shear.
Kiss-cut PSA parts: make the whole set placeable
A cushion or washer only earns its keep if assembly can place it in the right spot, right-side up, every time. That is what kiss-cutting is for: the part is cut through the material but not the liner, so it stays on a carrier web or a piece-part liner with a pull tab, and the operator peels and places it to the drawing.
H-O converts the pressure-sensitive-adhesive (PSA) side of every part on this page — a transfer adhesive or a coated PSA appropriate to the cushion and the substrate — and kiss-cuts the outline so the display gasket, the board pad, the standoff washer, and the flex bumper all arrive placeable. Adhesive selection is an engineering decision, not a default: the substrate, its surface energy, the temperature and exposure, the dwell before load, the assembly pressure, the surface prep, and the part geometry all shape which adhesive holds.
Send the substrate and the duty, and the adhesive and liner get chosen with the cut.
Six decisions that drive your display & board cushion spec
A display or board cushion is a single-purpose spring, and each has one controlling property. Miss it and the failure is rarely immediate: the cushion relaxes, the seal opens, the board flexes a little too far, or a part cannot be placed in assembly.
Materials carry classes; devices carry survival. UL 94 flame class belongs to a material grade per its TDS. Drop and shock survival (IEC 60068-2-31, -2-32, -2-27; MIL-STD-883 Method 2002) and the IP rating (IEC 60529) belong to the tested device. Write material classes on the part callouts, cite the assembly standards by designation, and never let a drawing imply that a cushion is “IEC 60068 rated”: the cushion supports a design evaluated to it.
Flexible cellular materials are characterized by density (Test A), indentation force deflection (Test B), compression force deflection (Test C), and compression set (Test D). Cushion and gasket grades are specified by their CFD window and their compression-set resistance — the numbers that decide whether the cushion still cushions and the seal still seals years later.
Read the six factors below in order. The first three build the display cushion (compression window, seal, impact); the next two carry the board and its isolation (dielectric standoff, keep-out); the last one makes the whole set placeable in assembly. Every factor names its test method or its assembly standard, and keeps the two apart.
Show all 6 selection factors tap to expand
Compression window: specify the force, not the thickness
Rule — a cushion is a spring specified by its compression-force-deflection curve, not its gauge. PORON® microcellular urethane holds its defining property, low compression set, so the cushion and seal force survive years of use; methods are per ASTM D3574, and the ultra-soft slow-rebound 4701-series 30-class grade is the display-bezel default because it seals at low closure force. Get the display-to-bezel gap and the closure force onto the drawing; firmness grade and thickness fall out of those two numbers. [1]
Seal duty: the display gasket is also a dust and moisture barrier
Rule — the perimeter gasket that cushions the panel is the same part that seals the display-to-chassis gap.
A continuous, correctly compressed bead of PORON® or silicone foam excludes dust and moisture; a gapped or over-compressed one lets ingress in. Draw the gasket as a continuous perimeter loop and match its compression class to the real closure force, and remember the IP rating is earned by the whole enclosure per IEC 60529, not by the gasket alone. Where the joint runs hot or needs a flame class, move to cellular silicone with its UL 94 grade. [8]
Impact & drop: cushion the panel and limit board flex
Rule — drop energy concentrates where the panel meets the housing and where the board is free to flex.
A continuous display perimeter cushion protects the screen; ShockSeal® 4790-79 pads at the board take the concentrated impact and limit the deflection that fractures BGA solder joints. Name the drop and shock target your device must support (IEC 60068-2-31 rough handling, IEC 60068-2-32 free fall, IEC 60068-2-27 / MIL-STD-883 Method 2002 shock), and cite it by designation: the cushions support the design; the survival result belongs to the tested device. [4]
Dielectric standoff: insulate and space the board
Rule — where the board meets a boss or a metal housing, the washer often has to insulate as well as cushion. Split the job by mechanics: a Kapton® polyimide or PET film washer where the layer must be a thin, dimensionally stable dielectric, and a PORON® cushion washer where it must even out screw-clamp stress and cushion the board. Call out inner and outer diameter, thickness, and whether the washer insulates, cushions, or both. (Rigid threaded standoffs are commonly molded UL 94 V-0 nylon — a partner-network molded form, not a part.) [10]
Flex keep-out: protect the FPC from chafe and crush
Rule — a flexible printed circuit that rubs a housing edge or is crushed at a fold fails intermittently first, then for good. Protect the routing with parts: a soft PORON® bumper where the flex crosses a hard edge, a low-friction PET or UHMW liner where it must slide, and a keep-out spacer that holds it clear of a pinch point.
Send the flex routing drawing with the keep-out clearance marked; the outline, the clearance, and the PSA come off that drawing, not the shear. These small parts earn their keep only if the tolerances are held.
Assembly: kiss-cut PSA so every part is placeable
Rule — a cushion is only useful if assembly can place it right, every time. Kiss-cutting keeps each part on a liner with a pull tab, so the operator peels and places it to the drawing. Adhesive choice is an engineering decision: the substrate, its surface energy, the temperature and exposure, the dwell before load, the assembly pressure, the surface prep, and the part geometry all shape which pressure-sensitive adhesive holds.
Send the substrate and the duty with the outline, and the PSA and liner are chosen with the cut; the whole set can ship kitted, one kit per device, in assembly order.
Specification Tools
Two tools to take you from “we're building a device” to here's the material checklist for the drawing set: a requirement-driven cushion-stack builder that assembles the layer list with its citations, and a side-by-side comparison of every family on this page.
1. Display & board cushion stack checklist builder
Check the requirements your device carries. The builder assembles the corresponding converted layers into a checklist with the family, what to send with the drawing, and the citation language (material classes per TDS; drop and shock standards by designation, survival with the tested device). The default selection is pre-built for a typical screened handheld; every layer is also printed in the material reference section, so nothing here exists only behind a script.
Cushion stack checklist: 4 layers selected
Each checked requirement adds its layer below. The list is the starting bill of materials for the engineering review, not a certification: material classes (UL 94) come from the grade TDS, and drop/shock standards (IEC 60068-2-31 / -2-32 / -2-27; MIL-STD-883 Method 2002) are cited by designation with the survival result belonging to the tested device.
- Display bezel gasket: PORON® 4701-series 30-class ultra-soft slow-reboundSend: display-to-bezel gap, closure force, gasket outline. Cite: ASTM D3574 methods; IEC 60529 at the assembly level.
- Board-level shock pad: ShockSeal® 4790-79 / PORON® 4701Send: board deflection budget, pad locations, drop/shock target. Cite: ASTM D3574 methods; IEC 60068-2-31/-2-27 by designation.
- Standoff washer: Kapton® polyimide / PET filmSend: inner/outer diameter, thickness, insulate/cushion/both. Cite: dielectric methods per the maker TDS.
- Assembly: kiss-cut PSA + liner + pull tabSend: substrate, surface energy, temperature/exposure, dwell. Cite: peel/shear per the adhesive TDS.
2. Side-by-side: display & board family comparison matrix
Every family called out on this page, with construction, the class that drives its selection, the standards its TDS cites, and the zone it serves. Click a column header to sort. Click any material name to jump to its accordion entry.
| Material | Construction | Selection class | Standards on the TDS / by designation | Zone | |
|---|---|---|---|---|---|
| The display side | |||||
| PORON® Industrial (4701-series 30 Class, 4701 Series, ShockSeal® 4790-79)Microcellular urethane | Microcellular PU foam | Compression window (CFD) | ASTM D3574; UL 94 per grade TDS | Display & board | |
| Silicone Foam (BISCO® 7xxx / HT series)Cellular silicone | Closed/open-cell silicone | Temperature / flame class | UL 94 per grade TDS; ASTM D1056 | Display & board | |
| EPDM / Crosslinked-PE / EVA FoamEconomical foam | Closed-cell foam | Light-duty cushion / seal | ASTM D1056 (per TDS) | Display / spacer | |
| Pressed Felt / Light-Seal LayersFibrous cushion | Pressed felt | Anti-rattle / light seal | Per the material TDS | Display / spacer | |
| The board side | |||||
| Kapton® Polyimide Film WashersDielectric film | Polyimide film | Dielectric / thin spacer | Dielectric per maker TDS | Standoff / keep-out | |
| PET / Film Spacer WashersSpacer film | PET / polyester film | Dimensional shim | Per the film TDS | Standoff / stack | |
| Crosslinked-PE / EVA Board CushionsResilient foam | Closed-cell PE/EVA | Firm cushion / bumper | ASTM D3575 (per TDS) | Board support | |
| Kiss-Cut PSA + Acrylic Foam TapeAdhesive layer | Transfer / coated PSA | Placement / bond | Peel/shear per adhesive TDS | Assembly | |
Skip ahead and request your engineering review now
If your drawing set already calls out a PORON® grade, a display gasket outline, a board pad, or a standoff washer, send it over for engineering review against the TDSs and the standards language.
Display & board failures you can prevent at spec
Screened devices fail quietly first: a cushion that relaxed, a dust seal that opened, a board that flexed a little too far, a flex cable that chafed through, a part that assembly could not place. Five patterns cover most of what goes wrong, and each is a specification decision made before the first part is cut.
Drop survival is an assembly result, not a material property. A correct cushion in the wrong place, or a drawing that claims an IEC 60068 rating for a pad, costs more schedule at review than any cutting error. Cite material classes per TDS and drop/shock standards by designation.
Show all 5 failure modes tap to expand
1. The cushion was picked by thickness, and the preload quietly expired
Fix — a display gasket or board pad chosen by gap fill is the right thickness on day one and the wrong spring forever. As it takes a compression set, the cushion softens and the dust seal opens; rattle, ingress, or a soft screen follow months later. Specify the force, not the gauge: state the closure force and gap, and pick the PORON® firmness grade whose ASTM D3574 CFD data holds the window across the deflection span.
The family's low compression set is what keeps the spec alive over the years; the ultra-soft 4701-series 30 class is the display-bezel default for exactly this reason. [1]
2. The dust seal opened where the gasket was gapped or over-compressed
Fix — the perimeter gasket has to be a continuous loop at the right compression to seal. A gasket drawn with a break, or crushed past its useful range at a tight corner, lets dust and moisture into the display cavity. Draw the gasket as a continuous perimeter and match its compression class to the real closure force; step to cellular silicone where the joint runs hot or needs a flame class.
And keep the IP claim honest: ingress protection is earned by the assembled enclosure per IEC 60529, the gasket is one contributor, not the rating. [8]
3. The board flexed on drop and cracked a BGA solder joint
Fix — when a device is dropped, the housing stops and the board keeps moving; unrestrained flex fractures brittle ball-grid-array solder joints. A board picked for support by screw locations alone, with no shock pad taking up the free travel, flexes too far at the worst-case face.
Add ShockSeal® 4790-79 or PORON® 4701 pads between the board and the housing ribs at the high-deflection locations, sized by the deflection they must control per ASTM D3574, and qualify the assembly to the drop and shock pulse it must survive (IEC 60068-2-31 / -2-27; MIL-STD-883 Method 2002) — the pads support that design, the survival belongs to the device.
4. The flex cable chafed through where nothing kept it clear
Fix — a flexible printed circuit routed against a housing edge, with vibration and thermal cycling working on it, abrades until a trace opens. The failure is intermittent first, which makes it expensive to find in the field. Protect the routing at spec: a soft PORON® bumper where the flex crosses a hard edge, a low-friction PET or UHMW liner where it must slide, and a keep-out spacer that holds it clear of a pinch point. Send the routing drawing with the keep-out clearance marked; the parts remove the field-trimming that starts most flex failures.
5. Assembly could not place the part, so it went in wrong (or not at all)
Fix — a bare cushion with no liner is hard to pick, orient, and place repeatably; on a fast line it gets misplaced, lifted, or skipped, and the protection it was supposed to give never happens. Kiss-cut every part on a liner with a pull tab so the operator peels and places it to the drawing, and choose the pressure-sensitive adhesive to the substrate and duty (surface energy, temperature, dwell, pressure, prep, geometry) rather than defaulting it.
The whole set can ship kitted, one kit per device in assembly order, so the line places a known good stack.
Material reference
Detailed specs for the families referenced on this page: the core cushion (PORON® microcellular urethane, including the display-bezel 4701-series 30 class and the ShockSeal® impact grade), the temperature/flame track (cellular silicone), the economical foams (EPDM, crosslinked-PE, EVA, felt), the dielectric films (Kapton® polyimide, PET), and the assembly adhesives (kiss-cut PSA, acrylic foam tape).
Values are per the maker TDS on file for each grade with the method named; drop and shock standards are cited by designation, with survival belonging to the tested device. H-O die-cuts, kiss-cuts, slits, and kits every family to drawing.
PORON® Industrial Microcellular Urethane (4701-series 30 Class, 4701 Series, ShockSeal® 4790-79)Display gaskets, board shock pads & cushion washers · ASTM D3574 methods · low compression set
Specify the force window and gap, not just thickness. The EV compression-pad discipline applies directly here at device scale; the deep version of this material lives on the small-battery-packs and wearables sibling pages.
Cellular Silicone Foam (BISCO® 7xxx / HT Series, flame-retardant sponge)Temperature-endurance / flame-class cushion & seal · UL 94 classes per grade TDS
Let a flame-class or temperature requirement pick the silicone track before cost does; the class is a material property per TDS, cited as such on the part callout.
Economical Foams & Felt (EPDM, Crosslinked-PE, EVA, Pressed Felt)Light-duty perimeter, spacer & anti-rattle cushions · ASTM D1056 / D3575 per TDS
Match the foam class to the real closure force and the duty; these families win on cost where set resistance is not the governing property.
Dielectric & Spacer Films (Kapton® Polyimide, PET, Protective Films)Standoff / keep-out / stack washers & shims · dielectric per maker TDS
Call out inner/outer diameter, thickness, and whether the layer insulates, spaces, or both; the dielectric properties come off the film maker's TDS.
Assembly Adhesives (Kiss-Cut PSA, Transfer & Acrylic Foam Tapes)Peel-and-place assembly & structural cushion bonding · peel/shear per adhesive TDS
Adhesive selection is validated to the joint: substrate, surface energy, temperature, exposure, dwell, pressure, surface prep, and part geometry all shape which adhesive holds. Send the substrate and the duty, and the PSA is chosen with the cut.
Polyurethane / Polyether Foam (General Cushion & Fill)Economical thin cushion and stack-fill layers · ASTM D3574 per TDS
A sensible economical default; move to PORON® where long-term compression-set resistance drives the cushion or seal spec.
SAE Pressed FeltFelt / Fiber Spacer Pads
Display & board cushioning: engineer-grade FAQ
Eleven of the questions we hear most from electronics and IoT device teams. If your question isn't here, send a drawing or call, engineering picks up.
Are these cushions rated to IEC 60068 drop or shock standards?
No material is, and no honest supplier will claim otherwise: IEC 60068-2-31 (rough handling shocks), IEC 60068-2-32 (free-fall drop), IEC 60068-2-27 (shock), and MIL-STD-883 Method 2002 (board mechanical shock) evaluate a device or assembly, so the survival result belongs to the tested device. What the cushions carry is their own documentation: material-level classes like UL 94 on the rated grade TDSs, the test methods behind their properties (ASTM D3574), and lot-code traceability.
They support designs evaluated to the drop and shock standards; H-O supplies the converted layers and the paperwork, and the device engineer owns the qualification. [4]
What material goes in a display bezel gasket?
An ultra-soft, slow-rebound PORON® microcellular urethane in the 4701-series 30-class range is the industry-standard display-bezel material: it conforms at low closure force so it seals the display-to-chassis gap without over-loading a thin panel, cushions the screen against impact, and damps vibration — three jobs in one part. Where the location runs hot or needs a UL 94 flame class, cellular silicone (BISCO® 7xxx / HT series) takes over.
Both are specified by their compression-force-deflection window per ASTM D3574, and both carry a kiss-cut PSA so assembly can place the gasket to the drawing. [9]
Does a display gasket really seal against dust and moisture?
It contributes to it. A continuous, correctly compressed perimeter gasket excludes dust and moisture from the display cavity, which is why the same part does the cushioning and the sealing. But the device's IP rating (the ingress code) is earned by the whole assembled enclosure per IEC 60529, not by the gasket alone — the gasket is one contributor among the housing joints, connectors, and vents. Draw the gasket as a continuous loop, match its compression class to the real closure force, and validate the IP rating at the assembly level. [8]
How do I size a PORON cushion for a display or board?
Start from the gap and the force. For a display gasket, the display-to-bezel gap and the closure force; for a board pad, the deflection you must control and the force it must supply across that deflection. Pick the PORON® firmness grade whose compression-force-deflection curve (ASTM D3574 Test C on the TDS) delivers that force across the deflection span, then set thickness from the gap and the curve.
PORON's low compression set is what keeps the force window valid over years of use, so the cushion still cushions and the seal still seals at end of life. [1]
What is a board-level shock pad, and where does it go?
It is a cushion between the PCB and the housing ribs or bosses that takes up the board's free travel when the device is dropped, blunting the flex that fractures ball-grid-array (BGA) solder joints. It goes at the high-deflection locations — typically away from the screw supports, where the board is freest to move. ShockSeal® 4790-79 is the dedicated impact grade for the highest-energy spots; PORON® 4701 grades cover general board support.
Board shock is qualified at the assembly level (IEC 60068-2-27 half-sine, up to MIL-STD-883 Method 2002 severities for rugged devices); the pad supports that design. [7]
What is the difference between IEC 60068-2-31 and IEC 60068-2-32?
Both are environmental-test standards for equipment. IEC 60068-2-31 (Test Ec) covers rough handling shocks — drop and topple, free fall, repeated free fall, and bounce — the knocks and falls a device sees during repair work or handling; its second edition (2008) replaced the 1969 edition and folded in the drop-test content. IEC 60068-2-32 is the free-fall drop test proper.
IEC 60068-2-27 (Test Ea) is mechanical shock with defined half-sine, sawtooth, or trapezoid pulses (for example 50 g / 11 ms). On this page they are all cited by designation; the cushions support designs evaluated to them. [4]
What goes on a PCB standoff washer, and do you make the standoffs?
The washer at a board mounting boss does one or both of two jobs: cushioning the board against the hard boss so a screw does not concentrate stress, and insulating the board from the boss or a metal housing. H-O the compliant cushion washers (PORON® or foam) and the dielectric spacer washers (Kapton® polyimide or PET film) to your inner/outer diameter and thickness.
The rigid threaded standoff itself is commonly a molded UL 94 V-0 nylon part — a molded form coordinated through a partner network, not a part; H-O converts the washers that sit with it.
How do I protect a flex cable (FPC) from chafing through?
Protect the routing with keep-out parts rather than hoping the routing stays put. A soft PORON® bumper cushions the flex where it crosses a hard housing edge; a low-friction PET or UHMW liner lets it slide without abrasion; and a keep-out spacer holds it clear of a pinch point or a moving part. These are small, tight-tolerance parts, so the outline and the keep-out clearance come off the routing drawing. Send the flex layout with the clearances marked, and the parts are cut to it — removing the field-trimming that starts most flex failures.
Why kiss-cut parts on a liner instead of loose cushions?
Because a loose cushion is hard to pick, orient, and place repeatably, and on a fast assembly line it gets misplaced, lifted, or skipped. Kiss-cutting cuts the part through the material but not the liner, so each piece stays on a carrier or piece-part liner with a pull tab; the operator peels and places it to the drawing, right-side up, every time. The whole set can ship kitted, one kit per device in assembly order, so the line places a known-good stack rather than assembling it from bins.
Does H-O mold or extrude these cushions, or convert them?
H-O and converts sheet, roll, and film stock to drawing — die-cutting, kiss-cutting, slitting, laminating, and kitting. H-O does not extrude or mold parts internally; molded parts such as rigid nylon standoffs are coordinated through a partner network. Conversion runs in Winsted, Connecticut under an ISO 9001:2015 certified quality management system with material traceability and lot-code TDS records.
What should I put on the drawing so the quote comes back right the first time?
By zone: for the display gasket, the display-to-bezel gap, closure force, and gasket outline; for the board pad, the deflection budget, pad locations, and the drop/shock target; for the standoff washer, inner/outer diameter, thickness, and whether it insulates or cushions; for the flex keep-out, the routing drawing with clearances; and for every part, the substrate for the PSA, any flame-class requirement, and prototype plus annual volumes.
Plus the standards language you need on the paperwork (material classes per TDS; drop/shock by designation). “Recommend the stack” is a valid callout: that is what the engineering review is for.
Glossary: terms used on this page
Quick reference for the cushioning, sealing, and drop/shock terminology used throughout. Each entry links to the relevant standard or test method where applicable.
Compression force deflection (CFD)
The force a cellular material exerts at a given compression, the curve that turns a foam pad into a specifiable spring. Reported per ASTM D3574 Test C [1] on the PORON® TDSs; display and board cushions are specified by their CFD window, not their thickness.
Compression set
The permanent, unrecovered loss in thickness after sustained compression, expressed as a percentage of the original thickness (ASTM D3574 Test D [1]). It is the property that decides whether a cushion still cushions and a seal still seals years later; PORON® microcellular urethane's low compression set is why it is the display and board-level default.
Indentation force deflection (IFD/ILD)
The force to indent a foam to 25% and 65% deflection (ASTM D3574 Test B [1]); the most common compression test for flexible cellular materials, used with CFD to characterize a cushion's firmness.
Microcellular urethane (PORON®)
A fine-pitch open-cell polyurethane foam with extremely low compression set, high resiliency, good vibration damping and impact absorption; ASTM E595 outgassing data is grade-specific (4701-50 / 4701-60 within NASA limits; the softer 4701-30 and 4790-92 exceed them) ([9]). The core cushion family for display gaskets and board-level shock pads; the ultra-soft slow-rebound 4701-series 30 class is the display-bezel default.
ShockSeal® 4790-79
The PORON® grade tuned for dedicated impact and shock protection ([9]), used at the board's highest-energy drop locations to blunt the flex that fractures solder joints.
IEC 60068-2-31 (by designation)
Environmental testing, Test Ec: rough handling shocks (drop and topple, free fall, repeated free fall, bounce) primarily for equipment-type specimens ([4]). Second edition (2008) replaced the 1969 edition; cited here by designation, with survival belonging to the tested device.
IEC 60068-2-32 (by designation)
Environmental testing, free-fall drop test for equipment ([5]); the drop-test companion to the rough-handling and shock standards, cited by designation.
IEC 60068-2-27 (by designation)
Environmental testing, Test Ea: mechanical shock with defined half-sine, sawtooth, or trapezoid pulses (for example 50 g / 11 ms) ([6]). Board and component shock qualification standard, cited by designation.
MIL-STD-883 Method 2002 (by designation)
The mechanical-shock test method for microelectronic devices; Method 2002.5 Condition B applies 1500 g at 0.5 ms half-sine, 5 shocks in each direction of 3 axes ([7]). The board-level shock severity for rugged devices, cited by designation.
IEC 60529 / IP code (by designation)
The standard defining the ingress-protection (IP) code for enclosures ([8]). The display gasket contributes to dust and moisture exclusion, but the IP rating is earned by the assembled enclosure, not by the gasket alone.
Flexible printed circuit (FPC) / flex cable
A thin, bendable circuit that routes power and signal between boards, the display, and the battery. Fragile against chafe and crush; keep-out cushions, slide liners, and spacers protect the routing.
Kiss-cut / PSA / liner
Kiss-cutting cuts a part through the material but not its carrier liner, so a pressure-sensitive-adhesive (PSA) backed cushion stays on the liner with a pull tab for peel-and-place assembly. The method that makes every cushion, washer, and bumper on this page placeable to the drawing.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
Standards, test methods & technical references
The standards, test methods, and maker technical data sheets cited throughout this page. Drop and shock standards are cited by designation: they evaluate a device or assembly, and the survival result belongs to the tested device. Standards editions current as of July 2026; verify against the publishing body before final spec. H-O materials are aligned to these standards through the source manufacturer's TDS, not independently certified by H-O unless explicitly stated on the quote.
[1] ASTM D3574
Standard Test Methods for Flexible Cellular Materials — Slab, Bonded, and Molded Urethane Foams. Defines density (Test A), indentation force deflection (Test B), compression force deflection (Test C), and compression set (Test D). The material-level methods behind the cushion and gasket properties on this page. astm.org (D3574)
[2] ASTM D2240
Standard Test Method for Rubber Property — Durometer Hardness. The hardness method reported on the firmer cushion and gasket grade TDSs. astm.org (D2240)
[3] UL 94 (by designation)
Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances (HB / HBF / V-0 classes). Flame classes belong to the material grade per its TDS; cited by designation on the part callouts. shopulstandards.com (UL 94)
[4] IEC 60068-2-31 (by designation)
Environmental testing — Part 2-31: Tests — Test Ec: Rough handling shocks, primarily for equipment-type specimens (2nd ed., 2008; cancels and replaces the 1969 edition and incorporates the drop-test content). Cited by designation; survival belongs to the tested device. webstore.iec.ch (IEC 60068-2-31)
[5] IEC 60068-2-32 (by designation)
Environmental testing — Free fall (drop) test for equipment-type specimens. The drop-test companion to the rough-handling and shock standards; cited by designation. webstore.iec.ch (IEC 60068-2-32)
[6] IEC 60068-2-27 (by designation)
Environmental testing — Part 2-27: Tests — Test Ea: Shock. Non-repetitive and repetitive shocks of standard pulse shapes (half-sine, sawtooth, trapezoid) at specified peak acceleration and duration. Cited by designation for board and component shock. webstore.iec.ch (IEC 60068-2-27)
[7] MIL-STD-883 Method 2002 (by designation)
Test Method Standard for Microcircuits, Method 2002 (Mechanical Shock). Method 2002.5 Condition B: 1500 g, 0.5 ms half-sine, 5 shocks in each direction of 3 mutually perpendicular axes. The board-level shock severity for rugged devices; cited by designation. quicksearch.dla.mil (MIL-STD-883)
[8] IEC 60529 (by designation)
Degrees of protection provided by enclosures (IP Code). The ingress rating is earned by the assembled enclosure; the display gasket is one contributor. Cited by designation. webstore.iec.ch (IEC 60529)
[9] Rogers PORON® microcellular polyurethane (TDS)
PORON® Industrial Polyurethanes product family and technical data sheets (4701 series, 4701-series 30-class display-bezel grade, ShockSeal® 4790-79 impact grade): extremely low compression set, high resiliency, vibration damping and impact absorption; ASTM E595 outgassing data per grade. Values per the grade TDS on file. rogerscorp.com (PORON Industrial)
[10] DuPont Kapton® polyimide film (TDS)
Kapton® polyimide film technical data: thin, high-temperature dielectric film used for insulating standoff and keep-out washers and tabs. Dielectric and thermal values per the maker TDS. dupont.com (Kapton)
[11] Rogers Corporation — LCD / display gasket application note
Application guidance for LCD/display gaskets: the display perimeter gasket cushions the panel, seals the display-to-chassis gap, and damps vibration; PORON® grades used within display stack-ups including gasketless OLED designs. rogerscorp.com (LCD gaskets)
Updated . Standards editions and links current at publication; verify against the publishing body before final spec. H-O converts materials tested to the methods cited; H-O does not certify devices. Lot-specific documentation available on request.
To review your display and board cushion design, send:
- Display and board outline drawings (DXF/STEP/PDF)
- Display-to-bezel gap and closure force
- Board deflection budget and pad locations
- Drop / shock target (IEC 60068-2-31 / -2-27)
- Standoff washer inner/outer diameter and thickness
- Flex routing drawing with keep-out clearances
- Flame-class requirement, if any (UL 94)
- Substrate for the PSA and any liner / pull-tab need
- Prototype and annual volume
Get a display & board cushion engineering quote
Send a drawing set, BOM, or device spec. We typically respond within one business day with a cushion-stack recommendation, prototype lead time, and TDS verification against your compression windows, seal duty, drop and shock targets, and standards language.
See also: related H-O application pages
Engineering content for the adjacent Electronics & IoT sub-applications and the parent hub. Each page covers material selection, failure modes, and converter-side process detail for its application family.
Sibling sub-application
Enclosure sealing & IP protection
The perimeter and joint gaskets that earn a device's IP rating: the sealing side of the same enclosure this page cushions.
Read the page
Sibling sub-application
Vibration & acoustic control
The damping and isolation side of the same devices: how the cushion families on this page de-tune resonance and quiet structure-borne noise.
Read the page
Sibling sub-application
Thermal management
The heat-path side of the board: thermal interface pads and heat-spreader materials that share the board real estate with these cushions.
Read the page
Sibling sub-application
Small battery packs
The battery-side compression and barrier stack in the same devices: the PORON® cushion discipline applied to small Li-ion packs.
Read the page
Sibling sub-application
Bonding, assembly & adhesive tape
The deep adhesive playbook behind this page's kiss-cut PSA layers: transfer tapes, acrylic foam bonding, and substrate-driven adhesive selection.
Read the page
Industry hub
Electronics & IoT
The full Electronics & IoT application family: enclosure sealing, EMI shielding, thermal, display and shock protection, batteries, wearables, and more.
Read the page
Material data & standards. All compression, dielectric, and temperature values on this page are taken from the source maker's technical data sheets with the method named (ASTM D3574, D2240; UL 94 classes per the listed grade TDSs).
Drop and shock standards (IEC 60068-2-31, -2-32, -2-27; MIL-STD-883 Method 2002) and the ingress code (IEC 60529) are cited by designation only: they evaluate a device or assembly, the survival and IP results belong to the tested device, and the materials on this page support designs evaluated to them.
H-O converts materials; H-O does not manufacture devices, design drop budgets, or certify devices, and does not independently certify materials against the standards unless explicitly stated on the quote. Verify against the maker TDS and your assembly-level qualification plan.
Conversion scope. H-O and converts sheet, roll, and film stock to drawing in Winsted, Connecticut: die-cut and kiss-cut gaskets, pads, washers, and keep-out parts, slit films and liners, laminations, and kitted cushion sets, with material traceability and lot-code TDS records. H-O does not extrude or mold parts internally; molded parts such as rigid nylon standoffs are coordinated through a partner network. Lead-time and MOQ details are in the process strip and the quote form above.