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ESDA Threshold July/August 2017

Question 1. Which one is more helpful in reference to auditing the EPAs, the ESD field meter or the ESD voltmeter?

Answer 1. The ESD field meter is probably overall more useful for general measurements around the EPA. The area of view is what is different between the two types of instruments. Small areas (<150 mm x 150 mm) cannot be measured with good accuracy with the Field Meter. The ESD Voltmeter can measure very small areas with good accuracy.

Question 2. How to realistically determine “allowed by the user specifications” (surely user is not free to choose his own values, by his will as he has to be within certain limits)?

Answer 2. Setting user specifications requires that the “user” have a good idea about the risk levels for any static charge (electric fields) and voltage that are present in close proximity to any unprotected ESD susceptible items. This knowledge of course comes from training and experience. It is hard to set specifications without knowing something about the process and risk to parts. In order for a facility to become certified to ANSI/ESD S20.20, any user set specifications have to be justified according to the risks. For instance, if you have 100 volt HBM devices, you would not set an ionizer imbalance at +/-150 volts.

Question 3. Within the document where one can see text: “an integrated checker or a meter” Is there a specific integrated checker that is best? Does the meter mean the lab digital AVO meter?

Answer 3. Integrated checkers are often used for wrist strap and footwear measurements. These are testers that are specifically designed for some special purpose. A meter could be the digital AVO meter as long as the output voltage and current meet the requirements of the test method. For almost all of the measurements in the ESDA test methods, the meter has to have 10 volts and 100 volts for the resistance measurements. (Granted there are a few exceptions)

Question 4. Could I rely on the high resistance RLC meter (I possess like DMR 3600 which is an RLC meter with 4 G Ohm maximum measurement capability) to perform audit measurements like foot ware or wrist strap testing (where 35 M ohm is maximum requirement) along with the metal electrodes (for example figure 4: Wrist strap test using meter)...?

Answer 4. Measurements greater than 1 megohm require a meter with voltage output of 100 volts. Under 1 megohm, 10 volts is required. If your meter has those values then it should be OK. For wrist strap measurements, the output voltage is one of the special situations where you would not apply 100 volts to a person unless the voltage is current limited – that is why 10 volts is used, even though the measurement may exceed 1 megohm.

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