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Don't Guess-Measure -- ESD control may not be a simple process, but solid process and materials measurement can often eliminate guesswork.

A few days ago, I received the following question from a reader of this column: "Does my process generate an electrostatic discharge and, if so, how much?" If the electrostatic discharge (ESD) coordinator was looking for a simple "yes" or "no," "X volts" or "Y joules," he may have been disappointed with my answer. Static control would be much simpler if simple "yes" or "no" answers could be achieved. Wouldn't it be great to trust our eyes and be able to say, "The floor looks clean, therefore, my ESD control process must be working?"

Alas, oversimplification often creates more problems rather than solutions. Effective static control need not be overly complicated but must go beyond simple observations and answers. We need a greater application of the frequently supplied answer-"measure it."

Why Measure?

Why take the time to measure your processes or materials? First, measurement allows problems to be defined accurately. From an ESD perspective, most environments are unique. What might cause an ESD problem in one environment may not cause a problem in another. Measurement helps identify whether or not a problem exists in a particular environment. Second, measurement helps develop solutions that apply specifically to the problems identified and can also identify and prioritize the areas requiring the most attention. If the insulators in an environment are not producing electrostatic fields, why purchase ionizers to solve a non-existent problem?

ESD measurement helps win the resources and financial or personnel support to solve a problem. A table of measurements, showing electrostatic potentials of 1,000 volts or more, on operators handling sensitive ESD devices, can be more effective in gaining resource approval and commitment than general comments from someone who has not yet visited the facility. Material measurements aid in the selection and purchase of ESD control products that can solve a problem. Measurement is also a good way to assess progress and results of past problem solving. A record of measurement can show a reduction of electrostatic potentials on personnel from 1,000 to 50 volts-proving that a solution is effective.

What to Measure

What do you measure in a facility? Generally, processes and materials suspected of generating electrostatic potentials or charge, such as personnel in the area, conveyor systems, monitors, insulators and carts, are measured. Processes and materials selected for ESD control, including wrist straps, packaging materials, flooring materials and ionizers, should be measured to ensure that each item continues to function properly.

Required Measurements

Two types of measurements should be considered: 1) electrostatic fields or potentials and 2) resistance or resistivity. A number of relatively inexpensive instruments are available to collect such measurements-resistivity meters, resistance test kits and electrostatic field meters. For process and facility evaluation, the facility's primary interest is an indication of whether a material or process generates high or low levels of electrostatic charge. Frequently, most facilities want an indication of whether a material is insulative or conductive. For material evaluation and qualification, a facility may need to conduct laboratory level tests, which may require more precise instrumentation.

Conclusion

Most appreciate the basics of static control, but effective ESD control does not often fit into a simple solution framework. By confirming what observations and intuitions indicate, surprises and guesswork can be eliminated. Implementing a comprehensive measurement system can lead a facility to a more effective ESD control program.

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Michael T. Brandt is a publicity consultant to the ESD Association and president of Marketing Resources Ltd., Rockford, IL; e-mail: mtb@mrlweb.com. This column is a regular contribution of the ESD Association, Rome, NY; (315) 339-6937; e-mail: eosesd@aol.com.

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Author:Brandt, Michael T.
Publication:Circuits Assembly
Article Type:Brief Article
Date:Sep 1, 2001
Words:606
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