United States January 2, 2003
Maintenance & Service Guide
Presario 1800 Series
Models: 1805 and 1810
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Electrostatic Discharge
A sudden discharge of static electricity from a finger or other conductor can
destroy static-sensitive devices or microcircuitry. Often the spark is neither
felt nor heard, but damage occurs. An electronic device exposed to
electrostatic discharge (ESD) may not be affected at all and will work
perfectly throughout a normal cycle. Although, it may function normally for a
while, then degrade in the internal layers, reducing its life expectancy.
Networks built into many integrated circuits provide some protection, but in
many cases, the discharge contains enough power to alter device parameters
or melt silicon junctions.
Generating Static
The table shows how different activities generate static electricity and at
different electrostatic voltage levels.
Typical Electrostatic Voltages
Relative Humidity
Event 10% 40% 55%
Walking across carpet 35,000 V 15,000 V 7,500 V
Walking across vinyl floor 12,000 V 5,000 V 3,000 V
Motions of bench worker 6,000 V 800 V 400 V
Removing DIPS from plastic tubes 2,000 V 700 V 400 V
Removing DIPS from vinyl trays 11,500 V 4,000 V 2,000 V
Removing DIPS from Styrofoam 14,500 V 5,000 V 3,500 V
Removing bubble pack from PCBs 26,000 V 20,000 V 7,000 V
Packing PCBs in foam-lined box 21,000 V 11,000 V 5,000 V
NOTE: 700 volts can degrade a
product.
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