ESD Tutorial Includes:
ESD Basics How ESD affects electronics components Protecting against ESD ESD protected area ESD workbench ESD work mat ESD wrist strap ESD clothing ESD storage ESD process ESD on a budget Design to combat ESD
ESD is important for anyone building, testing or maintaining electronics equipment. It is necessary to protect against the effects of ESD otherwise equipment will fail if it is not handled properly while it is disassembled. However the precautions taken by electronics equipment manufacturers may appear daunting and rather unnecessary for the hobbyist.
Fortunately it is possible to set up an acceptable antistatic area for electronics hobbyists and implement ESD precautions for comparatively little cost. By taking precautions against ESD, constructional projects are likely to be more successful, and if any repair work is undertaken in computers or other modern electronic equipment, there is far less likelihood of damaging them through the effects of static discharge.
Basic ESD protected work areas
Many electronics stockists carry conductive rubber mats and wrist straps for very reasonable prices. These can be installed very easily and they can prove to be a very worth while investment if a large amount of construction is envisaged. In fact the total cost of a simple antistatic work-station consisting of a mat and wrist strap could be less than the cost of components for a single project. If installation of ESD precautions means that a project operates correctly and is completed, it could well save the money invested in it several times over.
When installing an antistatic work-station it is imperative that great care is taken in connecting it up. The mains earth is normally used for grounding, but this means that great care must be taken to ensure there is no possibility of the work-station becoming live. It is best to use one of the special connection plugs for this - often they may be specially coloured for this. For example in the UK these plugs are often coloured yellow. If a normal plug is used there is a possibility that the wire could be pulled loose and touch a live terminal.
While it is important to ensure that any components and circuits are not damaged during the construction of a circuit, it is equally important to ensure that they are not damaged when they are being stored.
While new ESD containers may be too expensive for many hobby applications, it is often possible to re-use old containers. Often ICs will be supplied in tubes and these can often be re-used, although it should be remembered that they do have a limited life. Alternatively some ICs may be supplied in black conductive foam and again this can be re-used.
The anti-static bags can also be re-used. The more conductive black bags are less widely used than the clear plastic static dissipative types. Beware of using the black plastic bags for boards that have on-board batteries as these antistatic bags have sufficient conductivity to discharge batteries over a period of time!
The most important item of equipment that needs to be designed and constructed to ensure that it does not damage circuits and components as a result of ESD is the soldering iron. Few other items used for home construction are likely to require measures to ensure they do not damage equipment.
There is a wide variety of soldering irons available on the market today. Many are quite suitable for work with static sensitive devices. The main requirement is that the bit used for soldering should be earthed. In general it is recommended that the resistance to earth should be less than five ohms. Any irons which are thermostatically controlled should ideally use a zero voltage switching system. This prevents large spikes caused by the switching of the thermostat from appearing at the tip of the iron and causing damage to the equipment.