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Description / Abstract:
Scope and Purpose
The purpose of this guide is to describe the electromagnetic
threat posed to electronic equipment and subassemblies by actual
Electrostatic Discharge (ESD) events from humans and mobile
furnishings. This guide organizes existing data on the subject of
ESD in order to characterize the ESD surge environment. This guide
is not an ESD test standard. An appropriate ESD test standard
should be selected for equipment testing ([1], [3],
[B1]).1
The manufacturing, handling, packaging, and transportation of
individual electronic components, including integrated circuits,
are not discussed, and this guide does not deal with mobile items
such as automobiles, aircraft, or other masses of comparable
size.
ESD results in a sudden transfer of charge between bodies of
differing electrostatic potentials. In this guide, the term ESD
includes charge transfer whether or not an arc occurs or is
perceived.
ESD phenomena generate electromagnetic fields over a broad range
of frequencies, from direct current (dc) to low gigahertz. The term
ESD event includes not only the discharge current, but
also the electromagnetic fields and corona effects before and
during a discharge. In this guide the intruder is often a human,
but it may be any object that is moved, such as a chair, an
equipment cart, a vacuum cleaner, or the equipment victim itself,
whether or not it is in conductive contact with a human.
The equipment victim is usually a fabricated electronic
equipment or subassembly and is generally, although not
necessarily, at local electrostatic ground potential. The equipment
victim may be the receptor to which the discharge takes place from
the intruder; less frequently, the equipment victim may be the
intruder. Alternatively, the equipment victim may be affected by
the electromagnetic fields generated by a discharge between an
intruder and a receptor. Receptors and intruders that may not
themselves be equipment victims include furniture such as metal
chairs, carts, tables and file cabinets, as well as other
electronic equipment.
This guide discusses and cites references that describe the ways
in which a body builds up charge and the characteristics of
discharge currents and fields. Descriptions and references are also
given for electrical equivalent circuits to be used in
understanding and simulating the discharge current between intruder
and receptor masses.
Publications that are specifically referenced in the text of the
guide are listed in the Section 3, while Section 9 cites additional
publications in both ESD and related areas.
Most of the work that has been published in connection with
actual ESD is related to discharges from humans, usually grasping
or in association with a metal object. Far less published data
exists for discharges from humans without metal objects, and from
mobile furnishings, and virtually no data exists for discharges
from human torsos or clothing. For this reason, primary emphasis is
placed on discharges from humans with associated metal objects,
with some additional material relating to ESDs from mobile
furnishings. All discharges are assumed to take place in an air
environment.
Finally, all of the published time-domain data on which this
guide relies were taken using instrumentation with either a 400 MHz
or a 1 GHz bandwidth.
1 The numbers in brackets correspond to those of the
references in Section 3, and the numbers preceded by the letter "B"
in brackets correspond to those of the bibliography in Section
9.