We recently had a customer audit and they brought up our lack of humidity control. We have sensors around the production floor monitoring but lack a way of controlling the humidity levels. We’re curious to see what control measures other facilities have.
More importantly, we’re curious to know if our current ESD workstation, flooring, and continuous monitor testing/checks are an adequate verification for when the humidity levels do drop below 30%.
J-STD001 Reference
Zachariah,
It depends on what humidity level you used for product qualification. If you used the humidity that is in most STMs which is 12% +/- 3% then 30% humidity is well above that and shouldn’t be a concern. If you used the lowest annual humidity of the facility, which is allowed in ANSI/ESD S20.20, then as long as your actual humidity is above the lowest annual humidity in the factory, you should be fine as well.
Hello ,
Greetings of the day from India .
As our Andy Sir has clarified, the respective PQ tests per ANSI /ESD STMs needs to be conducted and certified @ Rh 12% +/- 3% in which case when the product is put into use at any Rh level over and above this is of no concern .
On the other hand if it has been qualified at the lowest annual minimum Rh% at the installed facility at less than 30 % or less it is of no concern when the facility’s Rh % goes down below 30%. If not, re qualification is advised when the Rh% is below the minimum recorded over the year.
Zachariah,
To address the controls part of your question, there are systems in industry that can monitor, alarm and infuse additional humidity (if needed) in to your production area. A cautionary note however, these can be expensive and a maintenance night mare.
In one of my previous locations we had such a system and it worked as advertised. However, I had additional administrative controls and processes in place to help mitigate. I set specific targets for when ionizers were to be used, actions to take such as stop work, if humidity dropped to a certain level, ensured that no components or WIP were not left out of protective packaging, limited or did not allow unnecessary insulators on the worksurface, ensured that grounding (either wrist strap or footwear or both) was properly utilized. But most importantly was the selection of materials used in the process and that they had been properly tested/qualified for use in my process using the STM’s that have been previously mentioned.
Hope this helps
Humidity per se isn’t required to be monitored. What is needed is that you can prove that your ESD measures work at all humidity levels. One way is to validate it at a specific humidity and thereafter make sure that the humidity stays the same. But that’s only one method. www.esdokay.com has data on how humidity affects ESD shoe performance.
