Kapton® FN - Tapes for wire insulation

December 3, 2019 By
CMC Klebetechnik GmbH

If cables require high chemical resistance, exceptional radiation resistance, low flammability, very good heat resistance and high dielectric strength, insulation with Kapton films is an elegant solution.

Kapton® is a high-performance material from DuPont and combines unique properties. The polyimide film is extremely temperature-resistant and retains its dielectric strength over a wide range. Specialized Kapton® grades are available for a number of applications. Kapton® is flame retardant according to UL94 V0.

For the production of foil-wrapped, insulated copper conductors, DuPont offers special foils that can be processed by means of heat welding. In principle, this involves applying a layer of a thermoplastic fluoropolymer to the Kapton® film. This thin coating melts at temperatures above 300°C (even higher, depending on the fluoropolymer PFA, FEP or PTFE used), creating a very durable bond. It is chemical resistant and pressure tight. The degree of overlap additionally determines, among other things, the dielectric properties, but also the flexural fatigue strength. The main advantage is the uniform thickness of the insulation layer, which does not show any reduction in the thickness of the layer at the corners of the conductor, as occurs with lacquer insulation.

Kapton® FN is a Kapton® film coated on one or both sides with FEP. As described above, the fluoropolymer serves as an adhesive, but also as a chemically more resistant surface. Thus, the positive properties of both materials can be used together, e.g. as a chemical-resistant membrane, for sealable bags, electrical heating foils and (insulation) sleeves. Use up to about 205°C continuous temperature.

Kapton® PRN411 has an even more thermally stable fluoropolymer (PFA, PTFE) coating on both sides. One side serves primarily as an adhesive and the other as a sliding surface. In addition, the fluoropolymer coating increases the resistance of the cable insulation. Particularly in the chemical and petroleum industries, for example, the service life of a cable can be drastically increased in this way. In this way, a CTI value of 1 is also achieved for polyimide, which in itself has a poorer classification, and water absorption is reduced at the same time. Such cables can also be used in environments exposed to radiation or outdoors with UV exposure. Use up to about 260°C continuous temperature.

Kapton® FCRC is also available for use in applications subject to particularly high levels of partial discharge (corona) (motor winding in frequency converter operation, e.g. e-mobility). This variant of Kapton® is extremely resistant to the effects of partial discharges. The DuPont data sheet provides information on this.

Kapton® FN - Tapes for wire insulation

Spiral-wound wire insulation for high dielectric strength and good corona (partial discharge) strength made of Kapton® FN or FCR (particularly resistant to partial discharge!)

CMC Klebetechnik also supplies a Kapton® adhesive tape with an aging-resistant acrylate adhesive coating for customers who do not want to implement a hot lamination process. Spiral-bonded, such cables are also tight over the long term, depending on the overlap and bending radius, and meet high dielectric requirements. Due to the high permanent heat resistance up to 180°C, energy-intensive winding setups can be realized, e.g. in high-performance coils.

The following variants of Kapton® FN are available on request:

Designation FEP HN FEP
Kapton® 120FN616
2.5 µm 25 µm 2.5 µm
Kapton® 200FN919
12.7 µm 25 µm 12.7 µm
Kapton® 300FN929
12.7 µm 50 µm 12.7 µm
Kapton® 500FN131
25.2 µm 76 µm 25.4 µm