Principles of ESD Control
As we face the next millennium, new design techniques
are producing smaller, faster, more-efficient products
with increasingly complex geometries that often
have very low tolerances to ESD. Controlling ESD
in today's manufacturing settings is therefore a
formidable challenge. However, if one focuses on
some basic principles when designing and implementing
a static control program, the challenge can be met.
The basics of electrostatic charge, discharge,
types of failures, ESD events, and device sensitivity
may be summarized as follows:
Virtually all materials,
even conductors, can be triboelectrically charged.
The level of charge is
affected by material type, speed of contact
and separation, humidity, and several other
can create catastrophic or latent failures in
can occur throughout the manufacturing, test,
shipping, handling, or operational processes.
Component damage can occur
as the result of a discharge from the component
as well as a direct discharge to the component.
Components vary significantly
in their sensitivity to ESD.
With this basic understanding of ESD and its impact
on your environment, you can then begin to develop
an effective ESD control program. In this article,
we will focus on basic principles of ESD control.
Basic Principles of Static Control
Sometimes, controlling electrostatic discharge
(ESD) in the electronics environment seems to be
a formidable challenge. However, the task of designing
and implementing ESD control programs becomes less
complex if we focus on just four basic principles
of control. In doing so, we also need to keep in
mind the ESD corollary to Murphy's Law, "no matter
what we do, static charge will try to find a way
1. Design In Immunity The first principle
is to design products and assemblies to be as immune
as is reasonable from the effects of ESD. This involves
such steps as using less static-sensitive devices
or providing appropriate input protection on devices,
boards, assemblies, and equipment. For engineers
and designers, the paradox is that advancing product
technology requires smaller and more complex geometries
that often are more susceptible to ESD.
2. Eliminate and Reduce Generation Obviously,
product design isn't the whole answer. The second
principle of control is to eliminate or reduce the
generation and accumulation of electrostatic charge
in the first place. It's fairly basic: no charge
no discharge. We begin by reducing as many
static generating processes or materials, such as
the contact and separation of dissimilar materials
and common plastics, as possible from the work environment.
We keep other processes and materials at the same
electrostatic potential. Electrostatic discharge
does not occur between materials kept at the same
potential or at zero potential. We provide ground
paths, such as wrist straps, flooring and work surfaces,
to reduce charge generation and accumulation.
3. Dissipate and Neutralize Because
we simply can't eliminate all generation of static
in the environment, our third principle is to safely
dissipate or neutralize those electrostatic charges
that do occur. Proper grounding and the use of conductive
or dissipative materials play major roles. For example,
workers who "carry" a charge into the work environment
can rid themselves of that charge when they attach
a wrist strap or when they step on an ESD floor
mat while wearing ESD control footwear. The charge
goes to ground rather than being discharged into
a sensitive part. To prevent damaging a charged
device, the rate of discharge can be controlled
with static-dissipative materials.
For some objects, such as common plastics
and other insulators, grounding does not remove
an electrostatic charge because there is no conductive
pathway. Typically, ionization is used to neutralize
charges on these insulating materials. The ionization
process generates negative and positive ions that
are attracted to the surface of a charged object,
thereby effectively neutralizing the charge.
4. Protect Products Our final ESD
control principle is to prevent discharges that
do occur from reaching susceptible parts and assemblies.
One way is to provide our parts and assemblies with
proper grounding or shunting that will "dissipate"
any discharge away from the product. A second method
is to package and transport susceptible devices
in proper packaging and materials-handling products.
These materials may effectively shield the product
from charge, as well as reduce the generation of
charge caused by any movement of product within
Elements of an Effective ESD Control Program
While these four principles may seem rather
basic, they can guide us in the selection of appropriate
materials and procedures to use in effectively controlling
ESD. In most circumstances, effective programs will
involve all of these principles. No single procedure
or product will do the whole job; rather effective
static control requires a full ESD control program.
How do we develop and maintain a program
that puts these basic principles into practice?
How do we start? What is the process? What do we
do first? Ask a dozen experts and you may get a
dozen different answers. But, if you dig a little
deeper, you will find that most of the answers center
around similar key elements. You will also find
that starting and maintaining an ESD control program
is similar to many other business activities and
projects. Although each company is unique in terms
of its ESD control needs, there are at least nine
critical elements to successfully developing and
implementing an effective ESD control program.
1. Establish an ESD Coordinator and ESD Teams
As the problem-solving style of the decade,
the team approach particularly applies to ESD because
the problems and the solutions cross various functions,
departments, divisions and even suppliers in most
companies. Team composition includes line employees
as well as department heads or other management
personnel. ESD teams or committees help assure a
variety of viewpoints, the availability of the needed
expertise, and commitment to success. An active
ESD committee helps unify the effort and brings
additional expertise to the project. Committee or
team membership should include representation from
areas such as engineering, manufacturing, field
service, training, and quality.
Heading this team effort is an ESD Program
Coordinator. Ideally this responsibility should
be a full-time job. However, we seldom operate in
an ideal environment and you may have to settle
for the function to be a major responsibility of
an individual. The ESD coordinator is responsible
for developing, budgeting, and administering the
program. The coordinator also serves as the company's
internal ESD consultant to all areas.
Before seeking solutions to your problems, you
will need to determine the extent of your losses
to ESD. These losses may be reflected in receiving
reports, QA and QC records, customer returns, in-plant
yields, failure analysis reports, and other data
that you may already have or that you need to gather.
This information not only identifies the magnitude
of the problem, but helps to pinpoint and prioritize
areas that need attention.
Document your actual and potential ESD losses
in terms of DOA components, rework, customer returns,
and failures during final test and inspection. Use
data from outside sources or the results of your
pilot program for additional support. Develop estimates
of the savings to be realized from implementing
an ESD control program.
3. Evaluate Your Facility, Processes and
Your next step is to gain a thorough understanding
of your environment and its impact on ESD. Armed
with your loss and sensitivity data, you can evaluate
your facility, looking for areas and procedures
that may be contributing to your defined ESD problems.
Be on the lookout for things such as static generating
materials and personnel handling procedures for
Document your processes. Observe the movement
of people and materials through the areas. Note
those areas that would appear to have the greatest
potential for ESD problems. Remember that ESD can
occur in the warehouse just as it can in the assembly
areas. Then conduct a thorough facility survey or
audit. Measure personnel, equipment, and materials
to identify the presence of electrostatic fields
in your environment.
4. Identify ESD-Sensitive Items
You will also want to identify those items (components,
assemblies, and finished products) that are sensitive
to ESD and the level of their sensitivity. You can
test these items yourself, use data from suppliers,
or rely on published data for similar items.
5. Build Justification for the Program
Once you understand your environment and the impact
that ESD has on your products and services, you
then build justification for your ESD control program.
You may even need to conduct a pilot program if
the experience of other companies is not sufficient
to help prove your point.
6. Get the Support of Top Management
To be successful, an ESD program requires the support
of your top management, at the highest level possible.
What level of commitment is required? Recently,
the CEO of a major electronics manufacturer was
asked to leave the production area when he failed
to wear the ESD control smock required by the company's
ESD procedures. He did so willingly and returned
later wearing the proper apparel.
That's the type of commitment you would like
to achieve. To obtain it, your program justification
will need to emphasize quality and reliability,
the costs of ESD damage, the impact of ESD on customer
service and product performance. Prepare a short
corporate policy statement on ESD control. Have
top management cosign it with the ESD coordinator.
Periodically reaffirm the policy statement and management's
commitment to it.
7. Establish and Implement Procedures and
Now you can develop and implement the appropriate
procedures that will help solve the ESD problems
you have identified in your company. Prepare and
distribute written procedures and specifications
so that everyone has a clear understanding of what
is to be done. Fully documented procedures will
help you with ISO 9000 certification as well.
Train and retrain your personnel in ESD and your
company's ESD control program and procedures. Proper
training for line personnel is especially important.
They are often the ones who have to live with the
procedures on a daily basis. A thorough understanding
of what is expected, and why, will have a significant
positive impact on proper long-term implementation.
9. Review, Audit, Analyze, Report, Feedback,
Developing and implementing the program itself
is obvious. What might not be so obvious is the
need to continually review, audit, analyze, feedback
and improve. You will be asked to continually identify
the return on investment of the program and to justify
the savings realized. Technological changes will
dictate improvements and modifications. Feedback
to employees and top management is essential. Management
commitment will need reinforcement.
Remember to provide both reporting and feedback
to management, the ESD team, and other employees.
Management will want to know that their investment
in time and money is yielding a return in terms
of quality, reliability and profits. Team members
need a pat on the back for a job well done and need
to know where to put their next efforts. Other employees
will want to know that the procedures you have asked
them to follow are indeed worthwhile. Conduct periodic
evaluations of your program and audits of your facility.
You will find out if your program is successful
and is giving you the expected return. You will
spot weaknesses in the program and shore them up.
You will discover whether the procedures are being
followed. As you find areas that need work, be sure
to make the necessary adjustments to keep the program
For Additional Information
Dangelmayer, Theodore. "ESD Program Management:
A Realistic Approach to Continuous, Measurable Improvement
in Static Control."
ESD ADV-2.0-1994. ESD Control Handbook.
ESD Association, Rome, NY.
Halperin, Stephen A. Facility Evaluation: Isolating
Environmental ESD Issues. EOS/ESD Symposium
Proceedings, 1980. ESD Association, Rome, NY.
to 1999 Annual Reference Guide Table of Contents