How to set up a simple EPA workstation

About ESD

A natural phenomena known as electrostatic discharge happens when electrons on a material's surface are redistributed, either by induction or triboelectric charging, in such a way as to produce a charge imbalance and an electric field. The charges will seek equilibrium across the potential difference when a static electric field is strong enough, which can lead to an electrostatic discharge, a powerful electrical shock. Humans are unaffected by these typical electrical shocks, but sub-micron microelectronic-based equipment may suffer catastrophic effects.

 

Definition of EPA

All surfaces, items, persons, and ESD Sensitive Devices (ESDs) within an ESD Protected Area (EPA) are maintained at the same electrical potential. This is accomplished by merely using "groundable" materials when covering surfaces and creating tools and containers.

 

An EPA (ESD Protected Area) is a defined space where no items or activity are able to cause damage to a sensitive device.

In the simplest case - a field work station - it may consist of a dissipative mat, a wrist strap and common grounding facility for both.

Wrist Strap

The wrist strap is the most used device to ground personnel, it will safely and effectively drain static charges from the body.

Anti-static Mat

An anti-static mat or ground mat allows electrostatic discharge to flow across the surface slowly, in a controlled manner, thus preventing the rapid discharge which can damage sensitive components. The mat is grounded by being connected to the mains plug outlet via an earth bonding plug. Both anti-static bench and floor mats are available for working with electronic components.

Grounding

The elimination of charge build-up is obtained by using conductive and dissipative materials that have less tendency to generate static charges. Grounding systems shall be used to ensure that components, personnel and any other conductors are at the same electrical potential. For proper and safe grounding the ESD ground must be tied directly to and at the same potential as the building or "green/yellow" ground.

 

Requirements

Remove all extraneous materials from the workstation (food, beverages, combs, bags, clothing etc).

Test the wrist strap/operator daily or install constant monitors.

Inspect the ESD grounding connections, the mats, the EBP, weekly.

Clean the surfaces with purpose-made anti-static cleaner, do not use commercial products, the cleaners may leave a residue insulative layer.