Compaq Presario 305 Spécifications télécharger pdf (Page 19)

Compaq Presario Series Maintenance and Service Guide

United States December 9, 2002

Presario 305 Model

Before You Begin Specifications Parts Catalog

Removal Sequence Troubleshooting Battery Operations

Product Description Pin Assignments

Index

Removal and Replacement Procedures

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 26,500 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.

Static-Shielding Materials

Material Use Voltage Protection Level

Antistatic Plastic Bags 1,500 V

Carbon-loaded plastic Floor mats 7,500 V

Metallized laminate Floor mats 15,000 V

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Compaq Presario 305 Spécifications Page 19