How does an electrostatic discharge work?

An electrostatic discharge (ESD) is one of the biggest invisible enemies of the electronics industry. Even a very small discharge can seriously damage sensitive components – often without anyone noticing.

What is an electrostatic discharge?

ESD is the sudden transfer of electric charge between two objects at different potentials. When one has a surplus of electrons and the other a deficit, the charge equalises almost instantly on approach or contact.

How does ESD occur?

1. Charge build-up

Walking, clothing friction, handling plastics or chair movement accumulate charge on the surface. See the article how static electricity arises for details.

2. Voltage build-up

If the charge is not dissipated, the voltage rises – walking across carpet up to 35,000 V, handling plastic up to 7,000 V, getting up from a chair up to 18,000 V. The current is usually small, but the voltage is enormous.

3. Discharge

On approaching a conductive object, the potential equalises abruptly – producing a spark, a current pulse and an electromagnetic field. It is this moment that damages the component.

Why is ESD a problem for electronics?

Modern semiconductors with tiny structures are extremely sensitive. A discharge can destroy them instantly or – more often – leave latent damage: the component works at first but fails later in operation. Latent defects are the most dangerous in quality assurance.

How to protect against it?

Effective protection relies on consistent grounding at an EPA workstation – wrist straps, ESD table mats and dissipative floors – in line with ČSN EN 61340-5-1.

Conclusion

An electrostatic discharge lasts only a fraction of a second but can cause irreversible damage. The article what is ESD covers the basics; find more guides in the ESD Guide.