In this exclusive article, the former Head of NBC (Nordic Baltics Countries) Torbjörn Lundberg from SMC shares insights on the ever-evolving world of automation and its profound impact on various industries.
Static electricity or Electrostatic discharge (ESD) causes many problems and costs a fortune every year. Cost estimates vary considerably but they are all in the 10’s of billions of Euros annually. To learn more about what causes ESD and how to protect against ESD saves a lot in yield in manufacturing and greatly in less damages when used. This article aims to explain static electricity, its dangers, and how to prevent it.
What is static electricity?
Kids play with static; you rub your feet on the carpet and give someone a good zap, also known as electrostatic discharge (ESD). Or you rub a balloon against yourself, and the balloon can cling to the wall or other objects. This is pretty fun and a little cute but, in a world, relying more and more on electronic devices, ESD has a more sinister reputation as the silent assassin to production.
All material is made of atoms, consisting of:
Usually, the electrons and protons are equal, so their charge is balanced. Thus, most material around us is electrically neutral.
But electrons are so tiny in mass, friction causes loosely bound electrons to attach to other surfaces. For example, this happens when two surfaces rub against each other. As a result, the surface which lost electrons becomes positively charged, and the surface that gained electrons become negatively charged. This phenomenon is called charge imbalance, and the molecules with unbalanced charges are called ions.
Higher temperatures create humidity in the spring and summer, and the water molecules make a safe "buffer zone" for ions to safely exchange electrons without the fast jumps that create ESD.
This is simply due to that dry air isolates better than humid air and then the exchange of electrons is no longer slow and safe but instead in fast jumps and sparks.
So, because the air is dry in the autumn and winter, we experience more electrostatic discharge events.
The danger of ESD
Static electricity may seem like a minor issue, but a single spark can generate up to 4 000 volts of electricity. The current is small but very hazardous to applications dealing with flammable materials, where ESD has been the cause of fires and explosions.
ESD can activate parasitic thyristors (unintended semiconductor structures) inside an integrated circuit, causing a high (and potentially damaging) current flow. The metal traces on printed circuit boards (PCB’s) are also vulnerable to ESD, which can cause localized melting or vaporization of metal traces. Modern nano technique electronics is very sensitive to static electricity.
Even worse, the resulting malfunctions sometimes don't occur for days, weeks, or even months after testing is complete. This is called latent damage, and it's notorious for shortening the lifespan of products. Not knowing the reasons for the breakdown, the reputation for the products and its manufacturer’s is damaged and difficult to remedy.
An ever-increasing desire to run the production faster and more efficiently, making goods and components wiz down the production line faster and faster also increases the risk of static electricity build-up. This movement is often enough to ionize the components and create an electric imbalance. This in turn attract other objects down the production line. In all stages of the production this is a serious risk.
It is not only electronics that are sensitive to static electricity. No one likes dust, dirt, pollen, and bacteria collecting on their product, but that is an unfortunate result when a product becomes ionized. When electrons are attracted to an item, they bring all sorts of nasties with them as they cling to their new surface. This potentially creates quality issues and possible health hazards for the end-user, depending on their application (especially food, beverage packaging, and printing/print quality on static sensitive materials.)
How to fight static electricity and ESD
There are different ways to eliminate or minimise the risk of static electricity and ESD:
-
Neutralizing ionized objects: The most effective way to combat ESD. If an object has an excess of negative ions, generate positive ions in the atmosphere around the object and vice versa. This is done by using different kinds of ionizers that measure the ions in the air around the objects to be protected, and then neutralise this air.
A company that offers equipment that neutralises the ion balance in production and material handling environments is SMC Automation. SMC offers a range of ionizers where air is the carrier of the ions. The simplest unit is a fan with ion emitter and built in automatic ion balancer. Despite its simplicity the effect is immediate, and this is suitable for many material handling situations where the risk for build-up of static electricity prevails.
Examples of applications
Other units for special applications include ionizer bars, ionizer guns and many more configurations. These units all have sensors for automatic control of the ion emittance.
SMC Automation has its roots in automation with compressed air. A way to use compressed air in prevention of damages related to static electricity is by blowing the surface that is potentially charged with static electricity with a blowgun that at the same time emits neutralising ions. Any dust, dirt, pollen, bacteria etc. that cling to a surface can easily be blown away after neutralisation with an ionizer.
Examples of applications
In combination with ionizers that neutralise the objects it is worth using components in your production line that are less likely to generate static electricity. Or rather help reducing the imbalance in electrons in the production area. One example of this is tubing that is conductive, simply not allowing any electric imbalance to build up.
To pay some extra attention to the risk of static electricity build-up in your production environment is a very worthwhile exercise. The cost of the work is very low and payback time often weeks or months – never years!
2024-10-01
Torbjörn Lundberg
