An electrostatic discharge (ESD) is the sudden micro-lightning bolt of electricity that flows from one charged, conductive surface to another conductive surface.
A typical example is when a person walks across a carpet and experiences a sudden shock when touching a metal doorknob.
The intermittent contact between the person’s shoes and the floor results in an exchange of electrons, which generates static charge on the conductive surface of the body. Once this static charge comes into contact with another conductive object, it discharges this static energy to restore the imbalance.
The hidden dangers of ESD
ESD might seem like a harmless occurrence, but in the electronics manufacturing industry, ESD can cause irreparable damage to electronic components. This micro-lightning bolt can burn holes through insulating layers and metal of microcircuits, causing it to malfunction.
Humans cannot detect ESD below 3000 V, but a discharge of as little as 60 V can destroy electrical components. Often the damage incurred is microscopic and goes completely undetected, only to cause a malfunction later (known as latent failure). This makes industries such as electronics manufacturing especially vulnerable to ESD.
According to a recent article published by Desco Industries, entitled ‘Increase your Return on Investment with a Successful ESD Control Programme’, ESD results in 10% of annual revenue loss, which translates into billions; not to mention the exorbitant costs of diagnostic, repair and maintenance of damaged components. In the same vein, companies have seen massive revenue savings, as much as 50%, after implementing a successful ESD control programme.
How ESD flooring prevents ESD damage
ESD flooring contains antistatic chemicals that enable static to dissipate through the floor to a ground point, and in so doing prevents discharges from occurring. For this reason, your first line of defence should be to invest in a robust ESD floor.
Before choosing a floor best suited to your needs, it’s important to 1) identify all ESD-sensitive objects in your facility, 2) install antistatic flooring in dedicated ESD protected areas, and 3) ground all personnel that handles ESD-sensitive objects.
Types of ESD flooring
When deciding on ESD flooring, you can choose between vinyl, epoxy or paint. Let’s take a closer look at your ESD flooring options:
Vinyl: an affordable, antistatic tile or sheet installed as a permanent ESD floor. Vinyl lasts long (10 years+) and there’s no need for regular maintenance. It comes in a variety of decorative styles. Vinyl is pliable and very popular in medical facilities for hygiene purposes. It is not chemical-resistant and therefore not recommended for acidic environments. Vinyl needs to be earthed by laying a conductive carbon or copper-based adhesive to glue down the sheeting.
Epoxy: a durable cement and carbon liquid mixture that is applied in coats onto existing hard-surface floors, such as concrete. Epoxy is impervious to acids and chemicals and it can be applied in layers to adjust the level of resistance as required. As this is a liquid coating, it requires repeat applications, depending on foot traffic. It is expensive compared to vinyl.
Paint: an effective antistatic coating for existing floors. Paint is a more affordable short-term solution and it is highly effective in preventing static build-up. However, it does require repeat applications.
Another important consideration when choosing an ESD floor is its resistance to earth, which indicates how strongly the material will resist the flow of electricity through it (measured in ohms). Remember, the floor needs to be able to conduct static electricity to a ground point, which means it cannot be completely resistant. For electronics manufacturing, the following material types are recommended:
Static Dissipative (SD): a hard-wearing, homogenous contact sheet or tile floor that is chemically treated to discharge static electricity. The resistance level of the floor does not need to be as low as that of conductive floors. SD must be used in a controlled environment with a relative humidity of more than 40%. Typical areas of use include electronics manufacturing, operating theatres, computer areas, instrument control rooms, repair centres and production facilities. This floor offers a resistance to earth of 5 x 106 – 1 x 109 Ω.
Electrostatic Conductive (EC): contains carbon in order to discharge electricity quickly and efficiently. It is typically used for electronics assembly/repair areas, in highly-sensitive medical equipment and highly sensitive computer equipment. This floor offers a resistance to earth of 5 x 104 – 1 x 106 Ω.
Once you’ve determined the resistance to earth required in your facility, you can select a floor cover best suited to your needs. It is important to match all ESD equipment to the electrical resistance required by your facility; for example, if your floor is SD, ensure the ESD consumables you purchase adhere to the same resistivity range.
The importance of proper grounding
ESD flooring cannot function without grounding equipment. Every person that works in the ESD protected area is a potential conductor of static electricity and needs to be grounded. Grounding devices provide a continuous path to ground and drain static build-up from the body through the floor to earth before it discharges.
The following consumables are all excellent grounding methods: wristbands and grounding cords, shoe grounders (with the option of heel grounders or removable, conductive insoles and outsoles) and grounding cords.
A chain is only as strong as its weakest link, so ensure to follow these best practices to complement your ESD flooring investment:
• Test all flooring and grounding equipment on a regular basis.
• Train everyone who comes into contact with ESD-sensitive objects.
• Mark ESD protected areas and objects clearly.
• Use only antistatic cleaning detergents in the ESD-protected area.
Partner with a credible provider
Altico Static Control Solutions, a division of Actum Electronics, focuses exclusively on ESD control in the working environment. Altico has partnered with the world’s leading suppliers of static control solutions and has been in operation for more than 20 years.
The company’s product offering includes complete ESD audit and recommendation services, ESD training, ESD consumables, cleaning materials, as well as the complete supply and installation of ESD flooring. It specialises in static control within the telecommunications, electronics manufacturing, medical facilities and industrial mining industries.
For more information contact Altico Static Control Solutions, +27 11 608 3001, [email protected], www.actum.co.za
| Tel: | +27 11 608 3001 |
| Fax: | +27 11 608 1918 |
| Email: | [email protected] |
| www: | www.actum.co.za |
| Articles: | More information and articles about Altico Static Control Solutions |
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version