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Devices sensitive to static
Devices sensitive to static
Introduction
Certain metal oxide semiconductor (MOS) devices embody in their design a thin
layer of insulation that is susceptible to damage from electrostatic charge. Such
a charge applied to the leads of the device could cause irreparable damage.
These charges can be built up on nylon overalls, by friction, by pushing the
hands into high insulation packing material or by use of unearthed soldering
irons.
MOS devices are normally despatched from the manufacturers with the leads
shorted together, for example, by metal foil eyelets, wire strapping, or by
inserting the leads into conductive plastic foam. Provided the leads are shorted
it is safe to handle the device.
Special
handling
techniques
In the event of one of these devices having to be replaced, observe the
following precautions when handling the replacement:
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When mounted onto printed circuit boards (PCBs), MOS devices are normally
less susceptible to electrostatic damage. However PCBs should be handled with
care, preferably by their edges and not by their tracks and pins, they should be
transferred directly from their packing to the equipment (or the other way
around) and never left exposed on the workbench.
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Always wear an earth strap which must be connected to the electrostatic
point (ESP) on the equipment.
Leave the short circuit on the leads until the last moment. It may be
necessary to replace the conductive foam by a piece of wire to enable the
device to be fitted.
Do not wear outer clothing made of nylon or similar man made material. A
cotton overall is preferable.
If possible work on an earthed metal surface. Wipe insulated plastic work
surfaces with an anti-static cloth before starting the operation.
All metal tools should be used and when not in use they should be placed
on an earthed surface.
Take care when removing components connected to electrostatic sensitive
devices. These components may be providing protection to the device.
Installation & Configuration: Horizon macro outdoor
68P02902W03-A
CONTROLLED INTRODUCTION
GSM-204-423
31st Oct 01
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