How much protection is enough? Ask yourself these five questions concerning ESD protection--you might not like your answers.

Perhaps the most frequently asked question in static control is straightforward and basic: How much protection is enough?

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The question is usually triggered by the need to make certain choices: If I have wrist straps, do I need electrostatic discharge (ESD) flooring? Do I really need ionization? What about garments and footwear? The protection issue is further impacted by financial considerations.

While the question may seem rather simple, the answer is not. Actually, two answers are correct--but both are answers that most ESD managers do not want to hear. The first suggestion is: enough to do the job; the second: it depends. Unfortunately, the issue is not a simple black and white situation, as much as we might like it to be.

The ESD Association's ESD control program standard, ANSI/ESD S20.20, provides program guidance for protecting devices and assemblies that are sensitive to 100V human body model (HBM) discharges. However, the document recognizes that ESD control programs require tailoring for specific needs and applications. Therefore, the standard provides a number of options.

To discover how much protection is enough, evaluate your manufacturing environment to understand possible static control problems. Ask yourself the following simple, key questions:

1. What is the ESD sensitivity of the devices and assemblies that we handle?

Products that are sensitive to 100V HBM discharges require different protection than those that are sensitive to 1,000V HBM discharges.

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2. What is the value of the final product and what are the company's annual losses to ESD?

The degree of protection is directly influenced by product cost and product losses. Find out the return on investment (ROI) in static control for your operation, not someone else's.

3. What is the risk of inadequate protection?

Find out whether or not your quality and inspection system is adequate to prevent damaged parts from being shipped. Is it less expensive to prevent damage or to discard damaged parts? You could be risking current and future business if you ship damaged products.

4. Which areas and processes provide the greatest ESD exposure to our products?

Discover where the potential problem areas exist in your operation--truly a key to determining how much protection is enough.

If your manufacturing process is primarily automated assembly and you are not experiencing significant problems in the manufacturing area, protective flooring in the area may not be warranted. If, however, you are experiencing significant problems in your rework area, then concentrate your efforts there. Problems may occur due to personnel handling products while seated at workstations; if so, implement wrist straps and protective work surfaces. If you also experience damage from highly mobile personnel as they move through the area, add protective flooring and footwear to reduce ESD generation. If electrostatic fields from insulators in the area create a problem, topical antistats or ionizers may also be needed.

5. Do you need to audit and evaluate your efforts?

You may find that the additional static control material or procedure did not solve your ESD problems. Or, you may find that changes in the area increased your ESD exposure. Hopefully, the corrections you make will greatly improve the situation, but periodic auditing or evaluation of your processes is the best way to monitor the results.

How much protection is enough? The answer lies in knowing and understanding your processes and facility to develop and implement the program that meets your specific needs.

Craig Zander, marketing and communications business unit manager for the ESD Association, is a manufacturer's representative at Restronics Co. Inc., Edina, MN; email: [e-mail]. This column is a regular contribution of the ESD Association, Rome, NY; [phone]; email: [e-mail].