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Application Note
AN-40-005 Rev.: OR M88352 (08/20/03) File: AN40005.ppt
This document and its contents are the property of Mini-Circuits.
The Prevention and Control of
Electrostatic Discharge (ESD)
(AN-40-005)
An Introduction to ESD
We experience occurrences of static electricity everyday. For example, walking
along a carpeted floor in a heated room during winter generates sufficient static
electricity to give us a rather shocking experience when we touch the door knob.
While this sudden discharge of static electricity does not result in any harm to
the human body, it can be very damaging to electronic devices which are
sensitive to electrostatic discharge (ESD). It is possible for electronic devices to
be damaged by ESD that is imperceptible to the human body. This document is
intended to shed some light on the sources of ESD and provides guidelines on
the prevention and control of ESD.
Object or process
Material or activity _
Work surfaces
Waxed, painted or plastic surfaces.
Floors
Waxed, common vinyl tiles, sealed concrete
Clothes
Common smocks, non-conductive shoes,
synthetic materials (e.g. nylon)
Chairs
Vinyl, fiber-glass, finished wood
Packaging
Common plastic bags, foam, trays, tote boxes
Assembly area
Spray cleaners, heat guns, blowers,
plastic tools (e.g. solder suckers, brushes)
cathode ray tubes.
What are the common sources of static electricity?
The following table shows a sample list of sources of static electricity.
What are typical examples of static charge inducing situations? Does
humidity have any effect on the induced static charge?
The following table shows some typical situations. Please note that humidity has
a significant effect on the induced charge. It is not recommended to have
relative humidity (RH) that is too low, say, below 30%. ESD control becomes
especially challenging at low RH levels. A relative humidity between 40% to 60%
is recommended for the typical assembly area.
Means of static generation
RH 10-20