Provided by the ESD Association
Going Beyond Color in Static Control
Leaving static control to visual inspection can lead to problems,
and clear definitions are essential for troubleshooting electrical events.
Q. What is the difference between a pink static bag and the gray
A. Although it once was common for manufacturers to distinguish between
different types of packaging materials by their color, this distinction
has ceased to be practical, if in fact it ever was.
Too often, however, trusting in the simplicity of visual inspection
creates more problems than it solves. Certainly, in static control this
is more the rule than the exception. Effective static control need not
be overly complicated, but we do need to go beyond the simplification
of distinction by color.
Although the emergence of ESD standards and general agreement on definitions
has helped to provide a degree of clarification, widespread education
is needed, as we still find much casual use of terminology. So, how
do we reduce the pitfalls of trusting our eyes?
To distinguish between the two bags, it is important to examine product
literature provided by each supplier. It may be necessary to conduct
your own testing or request independent test lab data from the suppliers.
By comparing published data and confirming them as necessary, it is
possible to identify the characteristics of different static bags and
to select the type most suitable for the application.
Q. What is the difference between EOS and ESD?
A. By definition, electrical overstress (EOS) is "the exposure
of an item (an electronic component, for example) to a current or voltage
beyond its maximum rating. This exposure may or may not result in a
catastrophic failure of the item." Electrostatic discharge (ESD)
is a specific type of EOS. ESD is "the rapid, spontaneous transfer of
electrostatic charge induced by a high electrostatic field. Usually
the charge flows through a spark between two bodies at different electrostatic
potentials as they approach one another."1
Typically, it can be inferred that an overstress has occurred when
an item fails to meet its electrical characteristics. Determining whether
the failure was caused by an ESD event or some other type of overstress
is often more difficult. In addition, overstress may result in latent
damage to an item. This damage is not immediately detected in its electrical
properties, but could result in a failure of the item later.
1. ESD-ADV 1.0-1994, "Glossary of Terms," ESD Association, Rome, NY.
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