Protecting PCBs from ESD
By concentrating on four basic concepts,
it is possible to find simple, focused solutions for controlling ESD.
Q. What is the best way to protect a printed
circuit board (PCB) from ESD?
A. Plenty of ESD solutions are available, but
there simply isn't a single best way. ESD is pervasive. Damage can occur
during rework, automated handling, or transport. Finding the best solutions
requires recognizing the problems, then selecting the best methods to
solve specific problems.
However, in designing and implementing
effective ESD control programs, it is possible to identify a simple
and focused solution. By concentrating on just four basic concepts,
the task of static control can become more manageable.
First, design products and assemblies to
be as immune from ESD as is reasonable. Use fewer static-sensitive devices
whenever possible. For those ESD-sensitive items that must be used,
provide appropriate input protection on devices, boards, assemblies,
and equipment. The more ESD control built into product design, the fewer
problems there will be.
Second, concentrate on eliminating or reducing
the generation and accumulation of electrostatic charge in the first
place. Get rid of as many static-generating processes or materials (such
as common plastics) as possible from the work environment.
Third, dissipate or neutralize electrostatic
charges by grounding dissipative or conductive materials in the environment
or by using ionization on common plastics or other insulators.
Finally, prevent electrostatic discharges
that do occur from reaching susceptible parts and assemblies. Grounding
or shunting devices and assemblies will carry any discharge away from
the product. Another method is the packaging, handling, and transporting
of ESD-sensitive devices and assemblies in proper packaging and carriers.
Nearly all static control efforts can be
simplified into one of four basic concepts:
Designing products with ESD protection and
a minimal number of ESD-sensitive devices.
Eliminating static-generating materials
Dissipating or neutralizing static charges.
- Providing physical protection from discharge
These four guidelines form the basis for
effective static control programs and simplify the selection of appropriate
materials and procedures. In most circumstances, effective programs
involve all of these concepts. No single procedure or product can do
the entire job.
To submit your questions to the ESD Help
Desk or to browse the archives of past questions and answers, go on-line
Information on the ESD Association may be found at http://www.esda.org.
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