Electronics designers rarely pick a foam on density alone. What matters inside a phone, a battery pack or a control box is how the material behaves at the interfaces: how it takes adhesive, whether it can be printed or laminated, how it behaves as a dielectric spacer, and whether it stays dimensionally stable across temperature. This article covers the surface, dielectric and lamination properties of IXPE foam (irradiated cross-linked polyethylene) for electronics use, and how to specify them.
Why IXPE Suits Electronics
IXPE is made by electron-beam cross-linking polyethylene before the foam expands. The result is a fine, uniform closed-cell structure with no open channels. For electronics that matters in three ways:
- No moisture path — closed cells do not wick water, so the foam will not carry electrolyte or condensation to a circuit.
- Clean, non-shedding — unlike open-cell acoustic foam or felt, IXPE does not release fibre or dust into a sealed enclosure.
- Stable under compression — cross-linked cells recover their shape, so a compressed gasket keeps applying force over the product's life.
Surface Properties and Treatments
Raw IXPE has a smooth, low-energy skin. That is good for release, and a problem for bonding. Our standard options are:
- Corona treatment — raises surface energy so adhesives, inks and coatings wet out and hold. Specify corona if the part will be laminated or printed.
- Embossing — a patterned surface for grip, controlled compression or a defined cosmetic finish.
- Calendaring — a controlled surface and tighter thickness tolerance, which matters for thin spacers.
Water absorption is low across the range: ≤0.2% for 3x–15x grades, ≤0.3% at 20x–25x and ≤0.4% at 30x–40x, measured to GB/T 1034 (method 4). Low absorption is what keeps a foam spacer from swelling in humid enclosures.
Dielectric Behaviour
IXPE is a non-polar polyethylene foam and a practical dielectric spacer: it is used between a cell and a case, behind a PCB, or as a separation layer in low-voltage assemblies. Two cautions matter more than any headline figure:
- Foam is not solid polymer. A closed-cell foam contains gas, so its breakdown behaviour depends on density, thickness and cell uniformity. Treat published foam dielectric values as indicative and validate against your own voltage, creepage and clearance requirements.
- Air gaps and edges concentrate stress. Cut edges and thin gauges are where breakdown starts, so prototype-test the finished part rather than the flat sheet.
For anti-static and conductive requirements, IXPE is not the right material on its own — conductive or ESD foam grades are specified for that job, where a target surface resistivity is defined by the application.
Lamination and Converting
Most electronics parts are laminated or die-cut rather than used as plain sheet. IXPE accepts heat bonding (multi-layer, 15–200 mm), adhesive lamination, and lamination to films or foils. Typical constructions:
- IXPE + pressure-sensitive adhesive — the standard mounting foam for cases and brackets.
- IXPE + aluminium foil — a reflective thermal layer for heat spreading and insulation.
- IXPE + conductive fabric or film — for shielding and grounding where a conductive path is required.
- Multi-layer IXPE — built up by heat bonding to reach a target thickness without changing cell structure.
Specification Data for Electronics Grades
The lower-density grades are the usual choice for electronics, because they seal with less force. Our measured IXPE values are:
| Expansion ratio | Density (kg/m³) | Tearing strength (kN/m) | Water absorption (%) | Thermal conductivity (W/m·K) |
|---|---|---|---|---|
| 15x | 66.7±8 | ≥4 | ≤0.2 | ≤0.065 |
| 20x | 50±6 | ≥3.5 | ≤0.3 | 0.055 |
| 25x | 40±4 | ≥2.5 | ≤0.3 | ≤0.049 |
| 30x | 33.3±3 | ≥1.3 | ≤0.4 | 0.045 |
| 35x | 28.6±2 | ≥1.3 | ≤0.4 | ≤0.040 |
| 40x | 26.8±3 | ≥1.2 | ≤0.4 | ≤0.040 |
Density to GB/T 6343, tearing strength to GB/T 10808, water absorption to GB/T 1034 (method 4) and thermal conductivity to GB/T 10297. Tensile strength and elongation are tested to GB/T 6344 and are available on the data sheet for the grade you select. Compression set at 23±2 °C for 22 hours is ≤10% (GB/T 6669), and dimensional change at 70±2 °C for 22 hours is around 3–4% or less (GB/T 8811) — both relevant if the part sits near a warm component.
How to Specify IXPE for an Electronics Part
- Function first — gasket, spacer, thermal layer or acoustic damper. The function sets density and thickness.
- Thickness and tolerance — single layer 0.5–14 mm; heat-bonded 15–200 mm.
- Density / ratio — 33–50 kg/m³ (20x–30x) covers most sealing and damping needs.
- Surface — corona if bonding or printing, embossed if grip or a defined compression curve is needed.
- Construction — plain, adhesive-backed, foil-faced or multi-layer.
- Validation — test the finished die-cut part for dielectric, compression set and outgassing in your own assembly.
Common Questions
Does IXPE contain halogens or plasticisers that could migrate? IXPE is a cross-linked polyethylene foam; specify your restricted-substance requirements to your supplier and ask for the declaration you need for your market.
Can IXPE replace silicone sponge in an enclosure? Often yes for sealing and damping at lower temperature, and it is lighter and cleaner. Silicone remains the choice where continuous high temperature is involved.
Which thickness should I start with? Prototype at 1–2 mm for gaskets and 0.2–0.5 mm for spacers, then tune from compression-force measurements.
See IXPE foam grades and full specifications → | Discuss an electronics foam part with us →
Related Reading
See also: Conductive and ESD foam guide · ESD foam solutions · XPE vs IXPE vs IXPP