Impregnation resins


Impregnation resins

Impregnation as secondary insulation

Impregnation is also known as secondary insulation because it reinforces the copper enamel that is defined as the first insulation. It is a chemical procedure that uses coating substances, such as resins and varnishes, plus heat, through a variety of methods, necessary to fix and improve the mechanical performance and stability, and improve the thermal and electrical performances of the copper winding parts.

bdtronic has experience with all current impregnation resins.

Overview impregnation resins


Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers, which contain epoxide groups.

Typical characteristics:

  • With or without solvents (e.g. for high-voltage applications)
  • Relatively high viscosity
  • Good adhesion
  • High mechanical resistance properties
  • High chemical and moisture resistence
  • Typically low aging properties at higher temperatures than polyesterimide resins
Polyesters / Unsaturated Polyesters
  • Typically thinned in monomers (unsaturated polyester UP) or solvents (saturated polyester PE)
  • Highly reactive & simple handling
  •  Medium adhesion & mechanical (brittleness) thermal class F-H
  • High temperature resistance
  • Class C use in traction motors
  • Some weaknesses in chemical and mechanical resistance
Sales worldwide

By using impregnation systems, manufacturers of automotive and electrical components are able to achieve improvements in the production and the repairs of these components. The choice of the correct material influences significantly the quality of the product and the final performances of the motor.

The choice is based on several factors that depend on the requirements of the product:

  • Mechanical strength at high temperatures
  • Heat transfer
  • Replacement of the air in the insulating system
  • Electrical insulation
  • Thermal and environmental resistance
  • Motor performance
  • Resistance to mechanical shock and vibration
  • Reduction of noise

The geometry of the product and of the copper wire/bar also influences the choice of the material having a direct impact on the ability of the resin to flow. Another parameter to be taken into account is the chemical and mechanical compatibility (adhesion) between the material and the primary insulation. Our technology center impegnation is glad to help its customers in the choice of the best material in combination with the final product and an optimized production process.

Technology Center

Benefit from our expertise and many years of experience. Develop the optimum process for your requirements together with us. We are specialists for different applications and processes.