Compaq XL118-XL127 - Manual (Page 82)

2 R EMOVAL S EQUENCE P RESARIO N OTEBOOK M AINTENANCE AND S ERVICE G UIDE 1200XL S ERIES
Presario 1200 Series
Models: XL101-XL113, XL115, XL118-XL127
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 seem to be
affected at all and works perfectly throughout a normal cycle. Although it may function
normally for a while, it may be degraded 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 below shows activities that generate static electricity and the associated
electrostatic voltage level.
Typical Electrostatic Voltages
Event
Relative Humidity
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.