This type of paint has long been used for wires, coils and capacitors installed in electrical/electronic equipment.Its applications are largely classified into the electric power field and the electronics fields.

Varnish coating is used for impregnating coils in the electric power field.This has made the equipment more compact and lightweight, improved its characteristics, including reliability, reduced costs, and produced more energy-efficient devices.Unsaturated polyester coatings are used for impregnating coils installed in small power transformers.This coating was adopted for its excellent workability, for example scraping can be performed easily after curing.

Polyurethane-based insulating coatings are one of the paints widely used for communication devices and home electronic appliances.The film of this paint has superior chemical resistance and electrical characteristics. In addition, soldering on this coating can be performed without peeling off the film.
Polyurethane paints with superior painting and soldering performance were also developed to improve the productivity or the reliability of this paint.For example, a 1 mm diameter baked enamel has superior flexibility and adhesive/soldering performance.The electrical wires with this insulation coating applied are used as a wire with minimized soldering time in reducing the effect on other components in light electrical appliances and shortening the work time, as well as in the process control.

Electric insulating paints with a heat resistance property have been developed as well.While motors and transformers are becoming more compact and lightweight, they require improved reliability such as the ability to run continually. Enamel wires used for these devices need to have more enhanced heat resistance.
Enamel wires in general are manufactured by applying organic resin dissolved or dispersed in solvents onto a copper wire, followed by a baking finish.Most of them are classified as polyimide varnish, polyester varnish, polyester-imide varnish, polyamide-imide varnish, and those mixed with ladder silicone-based oligomer for the improved heat resistance.
Repeat the process of applying these varnish coatings on a copper wire with a baking finish several times. To finish, measure the finishing diameter, the conductor diameter, the coating thickness, flexibility, thermal softening temperature, heat shock (200C° x 1hr.), and overload characteristics, etc.

An example of electrical characteristics of coil impregnating varnish is shown in [Table 1].

[Table 1] Characteristics of coil impregnating varnish