Dielectric strength can be defined as the maximum voltage required to cause a dielectric breakdown through the product. In other words, it is the measure of the insulating strength of a material. It is one of the most important factors in selecting an epoxy for various conformal coating, potting and encapsulation applications in the electrical and electronic industries, where excellent electrical insulation properties are a must.
The standard method used to measure the dielectric strength of a cured specimen is ASTM D149. It should be noted that the dielectric strength of an epoxy depends mainly on the thickness of the specimen and the test temperature. Some differences in dielectric strength can be noticed in filled systems when compared to unfilled systems. Also, dielectric strength varies depending on whether the product cures rigid or flexible.
Master Bond offers a wide range of products that have superior electrical insulation properties with high dielectric strength. Typically, the dielectric strength of Master Bond’s epoxies is about 450 volts/mil for a 0.125 inch thick specimen at room temperature. Many of our products with high dielectric strength also offer optical clarity, thermal conductivity, cryogenic serviceability and low outgassing properties.