What is ESD?
Electrostatic discharge (ESD) is the transfer of electrostatic charge between two objects caused by contact. While the discharge of energy resulting from this electron imbalance may be too minute for the human body to feel, it can nevertheless have serious consequences.
Familiar examples of ESD include the shock we receive when we walk across a carpet and touch a metal doorknob, or the static electricity we feel in winter from certain clothing. The threat of ESD looms everywhere in electronic work areas – floors, chairs, work surfaces, packaging materials, plastics and papers all give rise to static electricity.
Can ESD cause damage?
Yes. Many ESD events occur without a visible or audible spark. A relatively small electric charge is sufficient to damage sensitive electronic components, and even cause fires and explosions if the air contains combustible gasses or particles. Some devices may be damaged by discharges as small as 30 V.
These invisible forms of ESD can cause outright device failures and may affect the long-term reliability and performance of electronic devices. ESD damage can occur at any time – goods input, acceptance, production, assembly, testing, storing, packing, shipping or maintenance.
What can be done about ESD in the workplace?
Electrostatic protective areas (EPAs) that are free of static need to be created. An EPA is a defined space where no items or activities are able to cause damage to a sensitive device. An EPA needs to employ measures to prevent charging, such as avoiding highly charging materials, and taking care to remove static such as by grounding human workers and providing antistatic devices in the workplace.
What devices can be used to control ESD?
There are a number of devices available which can be used, and sometimes a combination of these needs to be used to be effective. These include wrist straps, conductive flooring, ESD shoes, ESD clothing, anti-static mats, ionisers and ESD-safe packaging materials.
How can ESD be tested in the workplace?
Handheld electrostatic instruments are useful to locate static charge problems; surface resistivity meters can test floors and bench mats. Actum Electronics conducts audits with a view to understanding what a customer’s specific requirements are and which ESD control measures should be put in place. Existing ESD protection systems need to be checked on a regular basis and customers need to be informed of their ESD status.
What types of ESD flooring are available?
Static dissipative (SD) flooring is a hard-wearing, homogenous contact sheet or tile floor covering which is chemically treated to discharge static electricity. Typical areas of use would be operating theatres, computer areas, instrument control rooms and production areas.
Electrostatic conductive (EC) floor coverings contain carbon and discharge electricity more quickly, so they can also be used in less controlled environments. In controlled environments, they would be used in sensitive electrical assembly areas as well as explosive manufacturing areas. As an example, Polyflor RoF flooring is predominantly carbon based and is used in explosive handling areas and in the mining industry.
Who needs ESD protection?
The medical, industrial, mining, manufacturing and electronics industries, as well as clean rooms, all require ESD protection. ESD control programmes are used by the military, hospitals and operating theatres, manufacturing areas and electronic production areas.
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| Fax: | +27 11 608 1918 |
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| www: | www.actum.co.za |
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