Many years ago, in an isolated part of the outback on the inevitable mine site in hot and dry conditions, one of our guys inserted a communications board into the PLC rack and inadvertently destroyed one of the key memory chips by electrostatic discharge (ESD). Fortunately, we had one backup board left. But it was a salutary lesson in being vigilant about the effects of ESD. No back up board could have meant significant down time while we waited for a replacement to be shipped to site.
The costs of electrostatic discharge (ESD) can have a significant impact on your business and work. ESD is the sudden flow of electrical energy between two objects after the build up of static electricity on the one object. The most common example is that of a person walking across the floor, who generates static electricity as his/her shoes intermittently make contact with the floor. Just sliding an electronic component in and out of a bag can destroy the electronic components. Believe it or not, but walking across the carpet (with up to 25% Relative Humidity) can generate 35,000 volts. We all work with electronic components and boards. And the newer components are becoming more and more sensitive to ESD problems.
A decrease in humidity tends to make the problem worse by increasing the level of static electricity (as the water molecules in the air vapour normally conduct some of the static charge away to ground thus reducing the problem – thus dryer air makes for less conductivity and more static electricity).
An Invisible Foe
Many times a day, ESD incidents occur below the human sensitivity threshold of 3000 V. Mostly never seen but causing enormous damage to circuit boards and sensitive electronic components. Remember that a small 100 volts can destroy an electronic component. It is claimed that the mere wave of the arm can generate sufficient ESD to damage an electronic component.
Costs Can Be Huge
It is claimed that high tech companies could be incurring costs up to 6% of their revenue due to ESD damage. Remember that the loss of a single component on a circuit board could results in a significant additional cost (well beyond that of the cost of the individual component) because of the need to replace or repair the entire board. This means the cost of failure of a $5 component could be hundreds of times greater.
An ESD To Do List
Some suggestions for dealing with the problem are listed below.
- Learn as much about your exposure to ESD at your firm. Consult widely. Esp. the internet and experts in the area.
- Identify sensitive work areas such as assembly, packaging stations, engineering and testing areas. Any where you handle electronic products which are unshielded or unprotected.
- Identify sources of ESD within your Work Areas. This includes such items as non-conductive materials (plastic parts, tape, cardboard and Styrofoam). Also computer monitors or laser printer paper.
- Assess the level of protection for each work areas. This may require innovative solutions such as using fibre optics or wireless to connect to sensitive devices.
- Prepare a Plan of Action. Put together a plan including easily understood procedures, responsibilities of key staff, training and checks that the plan is indeed being actioned.
- Implement Solutions. Install grounding mats and work surface mats where required. Ensure staff use wrist straps, heel straps and ESD-protective clothing (and shoes) to conduct static electricity away. Clearly signpost areas where potential damage may occur. Consider air ionization to neutralize charge build up on objects in the work area. Finally, educate staff in the key principles of ESD protection.
Maintenance is the key
Finally remember that you must maintain your ESD program. Wrist straps and other personal grounding devices require regular testing and replacement. Use a static charge meter to indicate the effectiveness of your system.
Thanks to an interesting white paper by Versalogic entitled: The Invisible Foe – Understanding and Controlling ESD Damage.
When fixing the problems with your ESD issues, Henry J. Kaiser's comment comes to mind: Trouble is only opportunity in work clothes.
Yours in engineering learning,