Dielectric Materials

When a dielectric material is exposed to a large electrical field, it may undergo a process known as breakdown. In that process, the material suddenly becomes conducting, and a large current begins to flow across the material. The appearance of a spark may also accompany breakdown. The point at which breakdown occurs with any given material depends on a number of factors, including temperature, the geometric shape of the material, and the type of material surrounding the dielectric. The ability of a dielectric material to resist breakdown is called its intrinsic electric strength.

Breakdown is often associated with the degradation of a dielectric material. The material may oxidize, physically break apart, or degrade in some other way that will make conductance more likely. When breakdown does occur, then, it is often accompanied by further degradation of the material.