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electrostatic discharge (wiring) (ESD)

Electrostatic discharges(ESD) are short-term, transient discharges. Such discharges can occur between solid, liquid and gaseous substances if they have different charges. They are usually accompanied by sparks or light effects.

Typical manifestations are the discharge of lightning, switching operations of powerful generators or motors, and the discharge of charged motor vehicles or human bodies. The discharges occur in extremely short time ranges from milliseconds down to nanoseconds. The discharge potentials can reach several kilovolts (kV) to megavolts (MV) and damage components such as MOSFETs, Schottky diodes, light-emitting d iodes, and even memory devices. The sensitivity of electronic components is divided into several classes.

ESD classes with voltage values

ESD classes with voltage values

Inelectronics, the electrostatic charge of human bodies plays a significant role, as the discharge could damage and destroy sensitive electronic parts, components and devices. The electrical energy that can build up in a human body is in the order of 10 milli-Joule (mJ) to 30 mJ, the electrostatic field can reach values between 100 V and 20 kV and depends very much on the floor covering and the air humidity. The high static charges cause short-term discharge currents of up to 30 A, with a current discharge of up to 100 A/ns. The electric field strength can reach values between 1 kV/m and 5 kV/m.

Protection against electrostatic discharges

Electrostatic discharges occur in workplaces, in cabling, automotive technology, equipment and circuit board technology, and in peripheral devices and monitors.

To protect ESD-prone components, Electrostatic Protected Areas( EPA) can be established in the workplace area, equipped with conductive and grounded table coverings, conductive floors with ground potential reference surfaces( ERP) and grounded tools. To prevent electrostatic body discharges, the clothing and footwear of personnel performing work are made of antistatic material, and personnel themselves may be connected to ground potential via antistatic wrist straps or grounding strap.

ESD wrist strap, photo: asmetec-shop.de

ESD wrist strap, photo: asmetec-shop.de

To protect the user, the Display Screen Equipment Ordinance describes measures to reduce electrostatic discharges and protect health. In addition to static-induced discharge, there is inductive-induced interference, or electromagnetic interference( EMI).

Warning signs for Electrostatic Sensitive Devices (ESD)

Warning signs for Electrostatic Sensitive Devices (ESD)

Simulation and ESD testing of sensitive electronic devices is performed using standardized ESD models: the Human Body Model( HBM), the Charged Device Model( CDM) and the Machine Model ( MM).

Informations:
Englisch: electrostatic discharge (wiring) - ESD
Updated at: 13.08.2015
#Words: 372
Links: electronic software distribution (ESD), light, lightning, memory, sensitivity
Translations: DE
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