Fowler Associates Labs

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.