Polyetherimide for magnet wire application
2022-01-0400
03/29/2022
- Event
- Content
- Magnet wire is composed of conducting core and thin layer of electrical insulation. Cupper (Cu) is typically used as conducting core, and various polymers such as polyamideimide, polyimide, and polyesterimide are used for electrical insulation. The role of magnet wire is involved in interchanging between electrical energy and mechanical energy for energy transformation application such as transformer, motor, generator, and many other equipment. Currently, electric vehicles (EV) industry is rapidly growing and consequential demands on related components are increasing as well. Compared to combustion engine, EV needs more electrical power with higher voltages or higher currents, which can increase probability of electrical discharge. The degradation of insulation layer can happen with the polymer bond breakage under the partial discharge electric stresses. To keep high performance under higher voltage, insulating polymer should have high heat resistances, chemical resistance, and low water absorption. In addition, adhesion property between insulating polymer and Cu should be secured to prevent crack issues. As an incumbent solution, polyamideimide (PAI) and polyimide (PI) is being used for this application as a varnish form. However, PAI absorbs moisture in humid environments or when immersed in water (up to 5% weight), which can cause reliability issue. PI shows very poor adhesion strength with the conducting core due to its stiffness and low surface energy. These properties can cause reliability problems for magnet wire. Therefore, there are strong demands to solve such issues like improvements in dielectric strength, water resistance, and high heat resistance. In this report, we will share the results of excellent flexibility, adhesion and electrical performance of polyetherimide (PEI, ULTEMTM resin) based varnish as a high voltage insulation material.
- Citation
- Kim, S., and Lee, D., "Polyetherimide for magnet wire application ," SAE Technical Paper 2022-01-0400, 2022, .