electrostatic discharge (ESD)
What is an electrostatic discharge?
Electrostatic discharge (ESD) is the release of static electricity when two objects come into contact. Familiar examples of ESD include the shock we receive when we walk across a carpet and touch a metal doorknob and the static electricity we feel from clothes coming out of the dryer. Lightning is also electrostatic discharge.
While most of ESD events are harmless to the human body, they can cause challenging and expensive problems in certain industrial environments. Static electricity is a problem for electronic and medical device manufacturing, vehicle fabrication, industries that use plastics and paper, and ones that need clean room environments. ESD issues can slow production, negatively affect product quality issues, attract contaminants and create safety issues.
What causes an electrostatic discharge?
An ESD event reflects a buildup of an electrostatic charge. This occurs when two different conductive materials, or conductors, rub together. One of the materials becomes positively charged; the other takes on a negative charge. The positively charged material now has an electrostatic charge. When the electrically charged object comes into contact with another conductive material, such as a Styrofoam cup or plastic bag, a static charge is transferred and an ESD event occurs.
How does electrostatic discharge affect electronic components?
High voltage isn't necessarily the issue with ESD. Many electronic devices are susceptible to low voltage ESD damage. For example, hard drive components are sensitive to 10 volts of electrostatic discharge.
The heat from an ESD event can be extremely hot, although we might not feel the heat when we are shocked. However, when the static discharge is released onto an electronic device, such as a semiconductor or an expansion slot or card, the heat from the charge can melt or vaporize the tiny parts, causing the part to fail.
Sometimes an ESD event can damage sensitive devices, but they continue to function. This is called a latent defect, which is hard to detect but ultimately shortens the life of the device.
How to manage and prevent ESD
Electrostatic discharges can occur without warning. Prevention requires understanding the environment in which an electronic device is manufactured, handled and used, and taking measures to reduce the likelihood of an event.
Electronics manufacturers incorporate various ESD protection measures to prevent issues in the manufacturing process, which includes fabricating, testing, shipping and handling. ESD preventive measures include the following:
- Use devices, chairs and other furnishing that are classified as ESD-safe.
- Ensure all devices and machines are grounded according to American National Standards Institute (ANSI) standards.
- Use personal grounding equipment and methods, such as antistatic wrist straps and footwear.
- Cover floors with antistatic mats that send charges into the ground and away from devices.
- Store devices in static-reducing containers.
- Package electronics using materials that shield them from ESD.
- Make antistatic spray available where appropriate.
- Only use static-attracting components in an area that is static-minimized.
- Avoid coming into contact with metallic parts or components, such as wires and connectors.
- Remove unnecessary components from static-protected work areas.
Knowing that an ESD can potentially damage electronic equipment makes it essential to include antistatic measures as part of daily IT operations.
Various standards help address ESD control issues and create protected areas. They define the sensitivity of the products to ESD and the requirements for specific measures in environments where electrostatic fields are a problem.
ESD standards are voluntary in the United States but can be included in sales agreements and other contracts. The EOS/ESD Association is accredited by ANSI to develop ESD standards and testing methods. The following are some of the ESD standards available:
- ANSI/ESD S20.20-2021: Protection of electrical and electronic parts.
- International Electrotechnical Commission IEC 61340-5-1: Protection of electronic devices from electrostatic phenomena -- general requirements.
- ANSI/ESD S8.1-2021: Standard for the protection of electrostatic discharge susceptible Items -- symbols.
- ANSI/ESD S6.1-2019: Electrostatic discharge grounding.
- ANSI/ESD S541-2019: Standard for packaging ESD susceptible materials.
Learn the best practices and safety standards involved in creating a comprehensive electrical safety strategy to keep your data center free of electrical hazards and protect sensitive components.