Читать книгу The ESD Control Program Handbook - Jeremy M. Smallwood - Страница 42

If a low voltage is applied across an insulating material, very little current will flow due to the high resistivity of the material. If, however, the voltage is increased, a level may eventually be reached where the current suddenly increases to a high value. Typically, this current flow may lead to formation and thermal heating of a small electrically conducting channel through the material. For a solid material, melting or damage of a small channel through the material may occur. This is dielectric breakdown of the material.

Typically, very high electrostatic field strengths are required for dielectric breakdown to occur. The breakdown strength of air is, for planar parallel electrodes, around 3 MV m⁻¹ or about 3 kV mm⁻¹. For curved or sharp electrodes, it is much lower. The breakdown strength of most insulating solids is much higher than air. For polyethylene, it is about 20 MV m⁻¹ (IEC 61340‐1 (International Electrotechnical Commission 2012)).