Electrostatic discharge

An electrostatic discharge (ESD) is a sudden flow of electric current through a material that is normally an insulator. A large potential difference across the insulator generates a strong electric field, converting the material's atoms into ions that conduct a current.

The best known example of ESD is a lightning strike. In this case the insulator that breaks down is air, the potential difference between cloud and ground can be millions of volts, and the resulting current that flows heats the air causing an explosive release of energy.

ESD may also be caused by so-called 'static electricity' that people experience in dry weather, when small sparks fly between insulating materials such as hair and clothing.

ESD is a serious issue in electronics, because integrated circuits are made from insulating materials such as silicon, which can break down if exposed to high voltages. Manufacturers and users of integrated circuits must take precautions to avoid this problem. Such measures include appropriate packing material, the use of conducting wrist-bands and foot-straps to prevent high voltages from accumulating on workers' bodies, anti-static mats to conduct harmful electric charges away from the work area, and humidity control, because water in the air conducts electric charges harmlessly to earth.