Compaq 190 manual Electrostatic Discharge, Generating Static

MAINTENANCE & SERVICE GUIDE

PROSIGNIA NOTEBOOK 190

INDEX PAGE	PRODUCT DESCRIPTION	LEGAL NOTICE	HOW TO USE THIS GUIDE
REMOVAL & REPLACEMENT	ILLUSTRATED PARTS CATALOG	TROUBLESHOOTING	SPECIFICATIONS

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

EventRelative Humidity

10% 40% 55%

Walking across carpet	35,000 V	15,000	7,500 V
		V
Walking across vinyl	12,000 V	5,000 V	3,000 V
floor
Motions of bench	6,000 V	800 V	400 V
worker
Removing DIPS from	2,000 V	700 V	400 V
plastic tubes
Removing DIPS from	11,500 V	4,000 V	2,000 V
vinyl trays
Removing DIPS from	14,500 V	5,000 V	3,500 V
Styrofoam
Removing bubble pack	26,000 V	20,000	7,000 V
from PCBs		V
Packing PCBs in	21,000 V	11,000	5,000 V
foam-lined box		V

NOTE: 700 volts can degrade a product.