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Precautions against damage from electrostatic discharge.

Summary

Some electronic components such as integrated circuits and laser diodes can be damaged by the discharge of static electricity as may become very noticeable when picked up from a nylon carpet. Although integrated circuits almost invariably include on-chip protection, this cannot always be relied upon as sufficient.

Sources of Static Electricity

Friction between two materials usually generates static electricity, and this can build up if one or both are non-conductors of electricity. Scuffing your feet on a nylon carpet can generate enough static electricity to create an uncomfortable discharge when you subsequently touch a metal object such as a handrail. A build-up of charge much less than you would notice can still be sufficient to damage some electronic components.

Static tends to leak away fairly quickly in conditions of moderate to high humidity, making only basic precautions necessary. But you will have to take extra care when humidity is low, for example during hot dry weather, but equally during a dry but frosty spell.

Susceptible Items

All electronic equipment is potentially susceptible to static discharge but most will survive all but the most extreme situations. Those items containing highly complex integrated circuits are likely to be most susceptible, such as computers and laptops, mobile phones and tablets, but many items these days contain embedded microcomputers. These often give themselves away by offering the user a menu to select items from instead of a mechanical switch.

The case and circuit board of any item will give the components within a good level of protection. The risk of damage arises when you take it out of its case, and in particular, as you start to disassemble it and disconnect its internal parts, or if you unsolder any of the components.

Precautions to take

Basic precautions suffice in most cases, and simply consist of touching a metal radiator, water pipe or tap, or any metal appliance with an earth lead, in order to discharge any static that has built up in your body. Do this before sitting down to work, and occasionally during the job.

In conditions of low humidity an antistatic wrist strap is recommended. This fits over your wrist or ankle so as to touch your bare skin, and has a coiled lead with a crocodile clip on the end which you can clip onto a suitably earthed object.

You can also obtain an antistatic mat to place on your workbench to work on. This will generally have a similar coiled lead and crocodile clip with which to earth it.

Static-sensitive components such as integrated circuits, RAM sticks and other laptop, phone and tablet spares are delivered in an antistatic bag. If you are replacing any such items, keep the replacements in their bags until needed.