Currently, I am supporting a company that manufactures batteries for electric vehicles, and they are facing the following issue.
The factory’s ESD (Electrostatic Discharge) flooring has not been tested for product verification. After a period of use, we conducted tests in accordance with ANSI/ESD STM7.1-2020 for compliance verification, with the factory’s lowest humidity level being controlled and a waiting time of 72 hours. We measured at least 5 points for every 500m². The results showed that many points did not meet the requirements.
What is the appropriate ratio of positions that meet the requirements versus those that fail to meet the S2020 standard?
Currently, non-compliant positions account for 43%(at 50%RH & 23 degrees). What risks does this pose to the products being manufactured at the plant?
Please give us some feedback
Thanks you so much.
DungNT,
Just want to clarify the terms you are using. ANSI/ESD STM7.1 is used for product qualification which is usually done before the flooring is used or as soon as you are moving to an S20.20 compliant ESD program. Compliance verification is done periodically throughout the lifetime of the floor at the users discretion (typically monthly or quarterly depending on how it is performing). Compliance verification of flooring is done per ESD TR53 section 7.3.9.
You asked “What is the appropriate ratio of positions that meet the requirements versus those that fail to meet the S2020 standard.” The answer is that all positions need to pass whether for product qualification or compliance verification.
You also asked the risk this poses to products. This would depend on how much the areas of the floor that fail are failing by and where these areas are in relation to where product is handled. If this is being done for product qualification, the flooring in combination with all approved footwear has to be tested for resistance and walking voltage per ANSI/ESD STM97.1 and STM97.2. These tests will give you a better idea of the risk, especially the walking voltage test. If you do the walking voltage test in an area that has the highest resistance and is an area where product is handled frequently, you should get a good idea of the amount of voltage a person could charge to. If this voltage exceeds the allowable HBM voltage of your product (100 V is the default for ANSI/ESD S20.20), then there is an elevated risk of an ESD event.
If it is determined that the flooring fails the testing then you could look into applying ESD coatings, like an ESD wax, to get the floors back in spec.
The risk to products depends on how much of the floor fails and where those areas are. For qualification, you’ll want to test resistance and walking voltage with approved footwear (using STM97.1 and STM97.2) to understand the risk level.
Hello,
Greetings from India
First of all, when you are mentioning 43% Non-Compliance even at 50% Rh it is a matter of concern about your basic floor material.
However, on the risk factor management issue, as Mr. Andy has mentioned already “This would depend on how much the areas of the floor that fail or failing and where these areas are in relation to the product handled which need to be protected against ESD hazards.”
You have not cleared the fact whether your floor is of Conductive or Static dissipative PVC/ Rubber (Single /double /three layer) OR of ESD epoxy. If it is of only single layer or of ESD Epoxy, of course here in India I have come across during many CV test audits major portion of the floor failing both with resistance and against walking voltage tests.
Thus, if it is at specific defined locations, it is better to change the floor material at those locations and reinstall with proper grounding connections. Prior to that it is better to get the floor material’s Product Qualification certification at both low and medium Rh% (as recommended per the standard test methods) If at random points you may clean those spots and try with some ESD floor coatings suggested by Mr. Andy.
Overall; as Mr. Andy has suggested earlier, it is essential that the floor should not only comply with Point to ground Resistance but shall be with respect to the walking voltage factor too (to be less than 100v), with different types /models of ESD safe footwear that you use on the ESD floor.
Good day
Thank you,