Beware of Electrostatic Discharge (ESD)!
NoteWhen you handle electronic circuit boards and modules, you must beware of the dangers of electrostatic discharge (ESD), both
to yourself and to the equipment. In order to ensure safe transport and storage, circuit boards and other electronic units will always be wrapped in a clear
plastic protective bag, and the bag will be sealed.
For correct and safe handling of printed circuit boards and electronic modules, you need a suitable working area. The working area must be covered by an approved conductive service mat that has a resistance of between 50 kΩ and 2 MΩ, and
is connected directly to a reliable earth point via its earthing cord. You - and all other service personnel involved - must wear a wristband in direct contact with the skin. The wristband must
be electrically connected to the service mat..
What is Electrostatic Discharge (ESD)?
Electrostatic Discharge (ESD) is the transfer of an electrostatic charge between two bodies at different electrostatic levels,
caused either by direct contact or induction by an electrostatic field. The passing of a charge through an electronic device can cause local overheating, and it can also "puncture" insulating layers
within the structure of the device. This may deposit a conductive residue of the vaporized metal on the device, and thus create a short circuit. Electrostatic Discharge (ESD) may result in a failures or degraded performance of the device.
ESD can create spectacular electric sparks (thunder and lightning is a large-scale ESD event), but also less dramatic forms
which may be neither seen nor heard, yet still be large enough to cause damage to sensitive electronic devices. Electric sparks
require a field strength above approximately 4 kV/cm in air, as notably occurs in lightning strikes. Other forms of ESD include
corona discharge from sharp electrodes and brush discharge from blunt electrodes.
ESD can cause a range of harmful effects of importance in industry, including gas, fuel vapour and coal dust explosions, as
well as failure of solid state electronics components such as integrated circuits. These can suffer permanent damage when
subjected to high voltages. Electronics manufacturers therefore establish electrostatic protective areas free of static, using
measures to prevent charging, such as avoiding highly charging materials and measures to remove static such as grounding human
workers, providing antistatic devices, and controlling humidity.
http://en.wikipedia.org/wiki/Electrostatic_discharge (January 2014)
Precautions to prevent Electrostatic Discharge (ESD)
Sensitive printed circuit boards and electronic modules must always be transported and stored in protective antistatic packing
bags. It as also important that they are not transported or stored close to strong electrostatic, electromagnetic or radioactive
fields. If it is necessary to open and touch the printed circuit board or module inside the protective bag, the following precautions
must be taken.
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1 |
For correct and safe handling of printed circuit boards and electronic modules, you need a suitable working area. The working area must be covered by an approved conductive service mat that has a resistance of between 50 kΩ and 2 MΩ, and
is connected directly to a reliable earth point via its earthing cord. |
|
2 |
You - and all other service personnel involved - must wear a wristband in direct contact with the skin. The wristband must
be electrically connected to the service mat. |
|
3 |
Printed circuit boards and electronic modules must be placed on the conductive service mat during installation and maintenance
operations. |
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4 |
If, for any reason, it is necessary to move the circuit board from the conductive service mat, it must be placed in an approved
antistatic transportation container (for example a static shielding bag) before transportation. |
|
5 |
During installation and servicing, all electrical equipment (for example soldering irons and test equipment) must be earthed. |