First Published in EOS/ESD Technology June/July
1998
ESD For Managers
Putting an ESD
program on a manager's action list makes
his or her life easier.
Glenn William Bodison
AT&T Microelectronics, Berkeley Heights, NJ
Ideas and issues competing for a manager's attention
and resources often seem endless. Knowing which projects and problems
to tackle can be confusing, and the temptation to minimize the number
of areas of concern is all too inviting. Why then do you need an ESD
program? Would it be just another headache, another burden? As a person
who has learned the benefits of implementing an ESD program through
experience, let me answer that question from a manager's perspective.
Starting With the
Basics
Let's start at the beginning. Who needs an effective
ESD program? Mainly, companies who make or use, or whose customers make
or use, ESD-sensitive devices such as microprocessors, ICs, transistors,
diodes and similar devices need an effective ESD program.
Next, in what areas will a company feel the effects of an ESD program
that is lacking in someway? An inefficient ESD program becomes evident
in customer dissatisfaction- when customers receive dead-on arrivals
or experience early-life failures. In addition, higher warranty and
internal failure costs can significantly affect operating results. Furthermore,
because of the difficulty in identifying ESD as the cause of a problem,
employee morale is often undermined by the frustration of a problem
that recurs, but which does not have an apparent cause.
Clearly, an effective ESD program can improve customer satisfaction,
operation results and employee morale. Therefore, the primary reason
an effective ESD program deserves the attention and resources of a manager
is, quite simply, that it makes good business sense.
Getting to Know ESD
ESD damage is a tricky issue. The voltage required
to damage many current devices is less than the human body's level of
sensitivity. (A spark only occurs at 3000 to 3500 V, and some devices
can be destroyed at less than 500 V.) The damage caused by ESD will,
with luck, kill a device immediately. But often you are not that lucky;
a device may be initially only wounded, but later will fail prematurely,
usually at the customer's location. Also, in some rare cases, ESD can
cause intermittent conditions.
The situation is only getting riskier. Without ESD protection, many
of the newer technologies that incorporate faster devices are more susceptible
to ESD with lower threshold voltages. Beyond this, as production processes
become more automated, equipment and conveyance equipment, if not properly
designed, can cause ESD damage. And seemingly insignificant factors,
such as floor was, can also contribute to ESD problems.
Even companies that do not make or handle ESD-sensitive devices still
may not be immune to ESD damage. In data-processing applications, for
example, ESD can change bits of information and cause processing errors.
Also, test sets often use sensitive devices and, without proper protection,
ESD can cause significant testing errors as well as test set maintenance
problems.
Considerations for
an ESD Program
A significant problem demands immediate attention.
However, ESD is often only a marginal condition that may comprise as
little as 0.5%, or up to 15 to 20%, of a problem. Nevertheless, it is
the lower-level failures (often accepted as being "Just the way
it is") that siphon off business resources. Problem solving, even
on these lower-level failures, makes a difference. Controlled experiments
repeatedly demonstrate that ESD-related defects can be drastically reduced,
and the rate of return on the protective measures generally exceeds
200%.
If you are a manager in an enlightened company (one that has an ESD
program) questions and problems still arise. You must closely look at
and question the effectiveness of your ESD program because, obliviously,
a program's effectiveness depends on proper usage and procedure. For
example, how often are wrist straps checked for continuity? Wrist straps
are of little use if they are not properly grounded, and so frequent
continuity checks are necessary. Also, if the inside wire breaks and
is not quickly detected, then a new source of damage has been created.
Some other questions to ask are: When ESD-sensitive circuits packs are
shipped, how are they packed- in styrofoam or in dissipative bags? In
addition to preventive measures in manufacturing shops, are engineers
required to use proper grounding techniques?
You must also ask yourself what you are doing to set ESD threshold limits
for new designs. As you accept new designs, are you insisting on actual
qualification data to prove that a new device or circuit pack design
can meet those limits?
With more companies developing just-in-time/quality control (JIT/QC)
programs, ESD control becomes increasingly important. It is impossible
to make JIT/QC work if there are ESD problems.
Clearly, with such numerous considerations, it is important to question
your ESD control program effectiveness; for this purpose a check list
is helpful (see checklist at the end of this article.)
ESD At Present
The circumstances surrounding ESD have drastically
changed. Late in 1965, a company I worked with was having a problem
with manufacturing a certain transistor. The yields had gone down. Failures
didn't seem to have a pattern. We would test them, and later, when Quality
Assurance retested them, they would still find defective transistors.
We put in long hours and conducted many experiments. Engineers, supervisors,
maintenance and manufacturing employees were at their wits end. In time
the problem went away as mysteriously as it began, but we could never
find the cause and didn't feel very good about that. Now that I look
back, I can see that the problem had many of the classic symptoms of
ESD. It began at about the time we turned on the heat and the relative
humidity dropped. There were intermittent and latent failures. Needless
to say, there was no ESD protection in place; we didn't even know the
ESD failure threshold voltage.
But today the phenomena of ESD are better understood. Every month new
discoveries are made. The range of new products to minimize these problems
is growing and improving, and more sophisticated ways of hardening devices
and circuit packs against ESD are being developed.
To take advantage of developments in ESD technology, a company needs
an individual or a small organization responsible for the ESD program.
If your ESD program is effective, it can result in improved customer
satisfaction, improved results and improved employee morale. As a manager,
that's where I want to invest some of my attention and resources.
Checklist for an Effective
ESD Program.
1. Management leadership involved
in an effective ESD program. Without this, lasting gains are
virtually impossible.
2. Comprehensive ESD policy that requires
all susceptible products to be hardened and protected.
3. Maintenance of formal ESD standards, requirements
and practices.
This includes device ESD-threshold qualifications, protection measures
that vary susceptibility, approved antistatic materials and equipment
grounding.
4. Clear responsibility in a full-time ESD coordinator
and steering committee.
The committee should include personnel from design, engineering, manufacturing
and quality.
5. Awareness training. This should cover
management, design, engineering and manufacturing.
6. ESD testing laboratory. This equipment
needs to be mobile so that it can perform tests in the operating environment.
7. Maintenance of ESD-related equipment and facilities.
This is required to assure that the protection is still being achieved.
8. Auditing and enforcement program. Companies
or locations using this consistently maintain the highest benefits from
their ESD program.
9. Keeping up to date on ESD technology.
ESD technology is rapidly changing as are related protective material
and techniques.
10. Continuous improvement and reinforcement.
This is necessary to maintain a strong and effective ESD program and
keep it running smoothly and efficiently.
