Kapton® FN Polyimide Coil

Kapton® FN is a heat-sealable composite of Kapton® HN polyimide film with Teflon® FEP fluorocarbon resin on one or both faces. In coil format it is supplied as a continuous roll — available in lengths from 0.1 m to 305 m — for uninterrupted feed into automated winding machines, slitting lines, and tape-laying equipment. Flat film pieces cannot sustain the continuous strip geometry that automated motor winding, cable taping, and roll-to-roll lamination lines require; coil format is the production-scale delivery of the same heat-sealable polyimide-FEP composite.

The FEP surface or surfaces on all gauges bond directly to adjacent film layers or copper foil under heat and pressure, at minimum peel strengths of 700 g/in (2.7 N/cm) film-to-film and 300 g/in (1.2 N/cm) film-to-copper. No adhesive is required. In continuous winding operations the seal forms as the tape is applied — on a magnet wire winding machine the wrapped turns bond to each other as the coil is wound and heat is applied — eliminating a separate bonding step and the adhesive layers it would introduce.

The 120FN (0.030 mm) grade carries FEP on both faces and has the highest minimum dielectric breakdown — suited to fine magnet wire insulation where the thinnest coil-format heat-sealable structure is required. The 150FN (0.035 mm) grade carries FEP on one face, providing an asymmetric construction suited to tape applications where one surface seals to the wire or film beneath and the other presents a bare polyimide interface above. The 200FN (0.050 mm) grade is available in single- and double-sided FEP constructions and offers the greatest abrasion resistance and mechanical robustness — the correct choice for motor slot liner strip production and heavier transformer winding applications.

All three gauges carry MIL-P-46112B and ASTM D-5213 certification and a UL thermal index of 200–220°C for mechanical properties and 220–240°C for electrical properties under UL file E39505. MIL-P-46112B is the qualification standard for aerospace wire and cable insulation, making the coil format directly applicable to aerospace cable taping lines where both material certification and continuous strip supply are required.

Kapton® FN coil maintains continuous service from −269°C to +400°C, with shrinkage controlled to 2.5% maximum in both directions at 400°C. In production, this means the coil survives the elevated temperatures of solder reflow, varnish cure, and thermal lamination cycles without dimensional change that would affect winding geometry or strip width uniformity across the full roll length.

The coil format is used in continuous magnet wire insulation winding, where uninterrupted strip feed into automated winding equipment and the heat-seal capability of the FEP surface support high-throughput production without adhesive; motor slot liner strip production, where consistent strip geometry and the abrasion resistance of the 200FN gauge meet in-slot performance requirements; transformer coil wrapping, where roll-to-roll processing and adhesive-free FEP bonding deliver efficient, high-volume coil insulation; and aerospace cable taping lines, where MIL-P-46112B certification and continuous coil feed meet both qualification and processing continuity requirements.

Yes. The coil format allows heat-seal process parameters — temperature, pressure, dwell time, and peel strength — to be characterised at production scale rather than on small flat coupons. ASTM D-5213 certification provides the traceable DuPont substrate baseline required for process validation documentation in motor, transformer, and aerospace insulation programmes.

Use coil format whenever the process requires continuous uninterrupted strip — automated winding machines, cable taping lines, slitting operations, and roll-to-roll lamination all depend on a continuous roll feed. Flat film pieces are appropriate for prototyping, sample-scale testing, one-off assemblies, and applications where a defined sheet sise is the correct input format rather than a continuous strip.

Kapton® FN Coil is available in all three gauges in lengths from 0.1 m to 305 m. Custom widths, slit-to-width service, and non-standard lengths are available on request. Contact us with your gauge, width, length, and required FEP construction.