This week’s ESD Q&A question::
Question: When measuring ESD Product such as ESD Mat resistance, I have noticed that the resistance measures higher on some of my older ESD rubber mats when using 10V and will sometimesÂ be greater than 10^9 ohms. SwitchingÂ to 100V will lower the resistance into the green, passable range(less than 10^9 ohms).Â If the mat passes at 100V, is that sufficient to give the mat a pass?Â When should I useÂ 10 volts vs. 100 volts?
Industry standards specify the test voltage required when testing or verifying ESD control items (i.e. mats). Â Â For verification of mats, or work surfaces, you can reference the ESD Association TR53 Compliance Verification document. Â This is a free download at www.esda.org (select the Standards tab and scroll down to TR53).
The following rule applies for resistance testing of ESD control items:
Perform the test at 10 volts. Â If the resistance is < 1.0 x 10^6 ohms record the reading.
If the measurement at 10 volts is â‰¥1.0 x 10^6 ohms, switch to 100 volts, make your measurement and record the result.
Most ESD mat materials are designed to have a resistance greater than 1.0 x 10^6 ohms, so you can start your testing at 100 volts. Â In the example that you stated, the mat that you tested meets the requirements. Â If you are seeing the values creep higher it would be wise to test the older mats more frequently to verify that they are still under 1.0 x 10^9 ohms.
Periodically, Transforming Technologies will answer questions concerning all things ESD: static causes, threats, Â ESD prevention, best practices and all things static in a feature we callÂ ESD Q&A. Â If you have ESD questions that you would like to be answered, emailÂ email@example.comÂ Â with Q&A in the subject line.