22/04/2024 – Advantage in >800V EV

Polyimide coated magnet wires

Electrical breakdown of high-temperature insulation materials can be prevented by using thermoplastic Polyimide (TPI). This polymer can be extrusion-coated as other polymers, but “Aurum” reduces electrical and magnetic losses.


“Aurum” coated magnet wires for high-voltage mobility applications. © Bieglo


“Aurum” has the highest Tg of any commercially available Thermoplastic, 245°C and its insulation performance especially at temperatures above 150°C beats any other know insulation.

As the automobile sector transitions to electric vehicles, new polymers that offer higher electrical and thermal properties are used. For better system integration, weight-reduction and downsizing in higher-volt systems, for faster charging and longer charging distances, electrical breakdown must be prevented by high-temperature insulation materials. “Aurum” reduces electrical and magnetic losses with a high comparative tracking index (CTI) >600V.

Thermoplastic Polyimide (TPI) produced by Mitsui Chemicals of Japan, and sold by Beiglo GmbH is known for excellent thermal stability, high-temperature resistance, and robust electrical insulation properties. TPI coated magnet wires are a suitable choice for high-voltage applications (800V and above).

Here are some key characteristics of “Aurum” coated magnet wires for high-voltage mobility applications:
– High-Temperature Resistance: Capable of withstanding elevated temperatures in general and best-in class performance near welding-spots.
– Thermal Stability: Provide thermal stability over a wide temperature range, ensuring the integrity of the insulation even well above 150°C continuously.
– Electrical Insulation: Excellent electrical insulation properties to prevent electrical breakdown and ensure the safety and reliability of the system.
– Flexibility: Maintain flexibility even at high temperatures, allowing for ease of winding during the manufacturing process and flexibility in the final application.
– Chemical Resistance: Resistant to many chemicals, enhancing the durability of the coating in various cooling environments.
– High Dielectric Strength: The high dielectric strength of “Aurum” helps in preventing electrical arcing and breakdown.
– Lightweight: “Aurum” coated magnet wires are lightweight, because even 30% less volume insulates better than other, commonly used materials.

“Aurum” is a semicrystalline TPI suitable for powder-coating, injection molding and extrusion coating, with highest-in-class glass transition temperature (Tg = 245°C). Extrusion processing “Aurum” for wire insulation is highly economical, allows extremely thin layers (30% to 40% thinner than PEEK), and has better elasticity and good compatibility with cooling-/ lubricating oils. Thermosetting polyimides have been known for many years in electronic insulation, but thermoplastic PI offers new ways of mass-producing Polyimide insulation for the automotive industry.

Extrusion-coated magnet wires and powder-coated busbars have been studied: performance parameters, including adhesion to copper and aluminum, temperature resistance, flexibility, and dielectric values, have all been evaluated and contrasted with PAI-enamels, PEEK-coating, and other insulation materials.

Bieglo GmbH
Bahrenfelder Strasse 242
22765 Hamburg, Germany
Contact person is John Biesterfeld
Tel.: +49 40 401130003