Preventing electrostatic discharge Chapter 1: ESD clothing
Maria Burkanova | 18. May 2020
Our bodies are very good electrical conductors. Electrostatic charging is almost unavoidable. Electrostatic charging occurs if you rub two materials together and then separate them, for example. Simply walking around can be enough to cause an electrostatic charge of several thousand volts. The invisible hazard – as described by experts. “ESD protection” is therefore very important as electrostatic discharging is often the cause of faults during the manufacture of sensitive electronic components. Protective ESD clothing” such as “ESD shoes”, an “ESD shirt” or “ESD work coats” can help to avoid this. It minimises electrostatic charging and ensures that discharging to earth takes place without any damage being caused.
What does “ESD protection” mean exactly?
ESD stands for “electrostatic discharge” and involves the restoration of electrical equilibrium. According to many studies, around 70 per cent of the damage caused to electronic components is due to improper protection. By simply wearing normal clothing, we ourselves are the main cause as such clothing often carries a high electric charge due to the amounts of plastic it contains. Sensitive electrical components can be damaged by a voltage of as little as five volts. One of the most important measures for the protection of sensitive electronic components is therefore ESD clothing as it provides protection against electrostatic charging.
What kinds of ESD clothing are there?
It is often assumed that an ESD wrist strap or ESD gloves are sufficient when people work with sensitive electronic components. But they frequently fail to provide sufficient protection. Further frequently used protective ESD clothing is, for example,
- ESD shoes or ESD safety shoes
- ESD gloves or work gloves for ESD areas
- ESD shirts
- ESD work coats
ESD shoes are ideal for protection of the feet against electrostatic charging. An example of why ESD shoes are important: if someone walks over a carpet and then touches a metal door handle, a small electronic voltage is often exchanged. Normal shoes with plastic soles cannot discharge this voltage. ESD shoes or ESD safety shoes must be worn, especially in electrical engineering areas where there are sensitive electronic components and also wherever there is a danger of explosion. Here, you can find a selection of ESD shoes for the workplace.
Work gloves for ESD areas protect the hands and fingers when sensitive components are being handled and thus enable safe working. This is important as we statically charge ourselves continually by moving about and the voltage is discharged as soon as we subsequently touch conductive objects. If the charge jumps over to sensitive electronic components, considerable damage or even a complete loss of function is possible. If antistatic ESD gloves are worn, the static is discharged whenever an earthed surface is touched. You can purchase ESD gloves here.
ESD work coats and tunics also hinder charging and remove any charge thanks to a grid of conductive fibres that are woven into the fabric. They are worn in medical areas and laboratories, for example. More about ESD work coats and tunics.
Wearers of an ESD wrist strap are connected via it to the earth connector and are protected against sometimes life-threatening accidents. Electric sparks therefore do not have a chance. The ESD wrist strap is connected to the earthed metal part of a machine, by means of a clip or a connector. It is used in all areas where electrostatic discharge can cause damage, for example, where components are being fitted onto a printed circuit board or where a computer with highly integrated circuits is being assembled. See Wikipedia for more information on antistatic wrist straps.
Why ESD protection is so important
People can charge themselves with more than 20,000 volts but even extremely small electric charges can cause considerable damage, for example:
- Damage to electronic components (30 volts is enough, 5 volts in the case of sensitive components)
- Deletion of information on magnetic data carriers (100 volts is enough)
- Fire caused by dust and fibres sticking to products
What normally triggers a brief scare in everyday life can mean the total destruction of electronic components that have semiconductor elements. In paintshops, an electrostatic discharge can even trigger an explosion. 50 volts is enough to cause a spark and ignite explosive gases. Protective ESD clothing ensures slow electrostatic discharging and prevents damage to machines.
What characterises ESD clothing in particular? What regulations are there in the workplace?
Protective ESD clothing is usually prescribed for people who work in areas where they come into contact with sensitive electronic components:
- Electronics manufacturing
- Computer engineering
- Telecommunications engineering
- Automotive electronics
- Production and manufacture of automatic machines/systems
- Technical customer service
- Installation sites
Medical staff are also often exposed to the danger of electrostatics as the devices they use are becoming more and more sensitive.
What properties classify work clothing as ESD safe?
Protective ESD clothing can be recognised by the character sewn onto it. ESD protection is adequately provided by the fact that conductive fibres are woven into the fabric so that the clothing does not retain the charge but discharges it. The woven-in fibres can then block off electrostatic fields of people. As a result, the electrostatic discharge is minimised or completely prevented. For ESD protection , there are standards – manufacturers and safety officers have to comply with them. DIN EN 61310-5-1 is the most common standard. It is complied with by using carbonised fibres. ESD clothing that can discharge static electricity must always cover the body as well as the arms and legs. Apart from ESD clothing , appropriate furniture such as conductive table tops, chairs, shelves and floor coverings in the ESD workplace can prevent electrostatic charging. Together with the corresponding soles of ESD shoes , floor coverings should guarantee that electricity is discharged to earth reliably.
Washing, storing and looking after ESD clothing – what must be borne in mind?
Dirt and soiling are problems as they can weaken the flame-retardant properties of the materials or even cancel them out. It is therefore important to wash ESD clothing. All items of clothing have a label indicating the materials used and the recommended washing instructions. These instructions must be complied with in order to maintain ESD protection and the ability to discharge electricity over the long term. Excessively high temperatures and softeners in the washing powder/liquid will possibly lower the effectiveness of the ESD clothing when it is washed . The permitted temperature is usually between 30 and 40 degrees. It should never be washed above 60 degrees. It is recommended that washing liquid be used and that softeners or bleaching agents be avoided. ESD clothing dries best in the air and should not be put in the dryer. Ironing is not normally necessary. If it is, the iron should be set to a medium temperature.
ESD clothing: summary
Wherever sensitive product parts can be damaged by a electrical charge, ESD clothing that discharges the electricity must be worn. Electrostatic charging takes place all the time. Uncontrolled equalisation is possible even without direct contact, which means that electronic components are endangered at all points along the production chain. For this reason, ESD protection is indispensable. This can be prevented with special protective ESD clothing such as an ESD work coat, ESD shirt, ESD wrist strap and ESD shoes. Such clothing contains woven-in conductive fibres that discharge electrostatic electricity. The employee and other objects are thus protected against electrostatic charging. All measures taken must match the environment and the products to be manufactured in order to guarantee the necessary ESD protection . It is also important to wash the ESD clothing according to the recommendations of the manufacturer. High-quality protective ESD clothing is mainly available in specialist stores.