TABLE OF CONTENTS Potentially damaging electrostatic discharge to electronic components and equipment caused by contact with human beings, tools and office furnishings has been of concern since at least the early 1970s [10]. The ESD problem can be considered in two areas:
ESD to vulnerable components such as MOSFETs in manufacture, storage, handling, transport and assembly into products.
ESD to finished products such as desktop computers in the operational environment. This is caused by the electrical charging of humans and furniture etc. in dry air-conditioned offices fitted with carpets and chairs made from synthetic materials.
It is estimated [10] that the cost of ESD damage in the USA alone was around ten billion dollars a year in 1988, and that this may increase as devices become more sensitive with increasing scale of integration. Control of ESD in the first category, the production phase, is amenable to control through the implementation of careful procedures and the use of special antistatic bags and containers.
Four generations of antistatic materials have been produced:
First generation pink polythene
Developed in the 1970s it has a surface resistivity of between 10 9 and 10 12ohm per square, but it had low stiffness, poor dimensional stability, short-lived electrical properties and was easily damaged by solvents.
Second generation antistatic polypropylenes
This material owes its antistatic properties to hygroscopic additives which draw in moisture from the air. It has the same resistivity as pink poly but persists for longer; for...
