4.4 Preventing Electrostatic Damage

Many electronic components are sensitive to electrostatic discharge (ESD). Circuitry design and structure determine the degree of sensitivity. 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.

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 may not be affected at all and can work perfectly throughout a normal cycle. Or it may function normally for a while, then degrade in the internal layers, reducing its life expectancy.

Packaging and Transporting Precautions

Use the following grounding precautions when packaging and transporting equipment:

■To avoid hand contact, transport products in static-safe containers such as tubes, bags, or boxes.

■Protect all electrostatic-sensitive parts and assemblies with conductive or approved containers or packaging.

■Keep electrostatic-sensitive parts in their containers until they arrive at static-free workstations.

■Place items on a grounded surface before removing them from their container.

■Always be properly grounded when touching a sensitive component or assembly.

■Place reusable electrostatic-sensitive parts from assemblies in protective packaging or non-conductive foam.

■Use transporters and conveyers made of antistatic belts and roller bushings. Ensure that mechanized equipment used for moving materials is wired to ground, and that proper materials were selected to avoid static charging. When grounding is not possible, use an ionizer to dissipate electric charges.

Removal and Replacement Preliminaries 4-3