Dear ESD Experts
what are the methods for detecting failures related to ESD in smt and assembly lines:
1-In the case of the use of equipment, what would this equipments be?
2-In case we prefer to use data analysis and statistics ?
my goal is to know a method that allows me to prove that ESD events are happening in certain places,and due to some process steps.
To answer your question in detail would be very long and basically repeat what is currently in ESDA standards today. When you say “detect an ESD failure” I take that at a component level. Meaning how do you understand if a part failed due to an ESD event or other reason. This analysis can be very expensive and difficult and I venture to say most electronic manufacturers would not have that equipment in house. But rather would send the parts out for analysis or back to the manufacturer.
That all said, we focus our efforts on preventing the ESD event from being able to occur within the manufacturing process. I would recommend reviewing documents such as S20.20 and TR53 to familiarize yourself with requirements and verification test methods. Investing in a ESD audit equipment kit (readily available from multiple suppliers) will get you started in the right direction. There are also event monitors that can be installed within your equipment to detect an ESD event. But I would start with auditing of all of your process steps if that has not been done as of yet.
Hope this helps.
Dear Mr Chris
thank you for helping
about the implementation of the ESD prevention process it looks to me that it is correct in the EPAs we have:
- all the conductors are grounded
- the insulators are neutralized by the ionizers
- and during transportation of ESDS we use only antistatic ESD bags
- Here is the problem I encountered:
when unpacking items received by the supplier (item in metalized packaging and in polystere inside a cardboard box), chain operators performing the gesture receive an ESD (probably due to triboelectricity in removing the items from the box)
what I do not find normal is the fact that humain bodies can feel this discharge , even that all grounding steps and the neutralization are done.
what would an expert act in this case
So sorry for lateness of this response, but I hope you were able to solve the issue.
My question would be how are the items packed? If they are ESD sensitive than they should be in static shielded bags. As such, they would be protected during the unpacking process. If not, and the charge generated is sufficient for damage, than you must reduce that charge. Most likely with ionization I am thinking. Hope this helps.
There are ESD Event indicators that can characterize the extent of the ESD discharge. Humans don’t sense ESD discharges below several kilovolts. The static protective packaging should protect the parts but with a mix of tribo-generators in the packaging materials, you could consider Ionizers to minimize the ESD exposure even further. I would keep track of the relative humidity as well is probably a bigger variable that one realizes,
I recommend becoming familiar with the following publications
-ANSI/ESD SP17.1-2020 sections 6 (general but very good information) and section 7 which identifies individual assessments.
- ANSI/ESD SP10.1 also offers information regarding Automatic Handling Equipment
With that being said, check resistance to ground of the SMT line fixtures to ensure you meet the worksurface requirement (<1E9ohms), implement ionizer usage wherever possible.
Once a board has parts on it, ensure it does not charge up to more than 1/10th the voltage of the most ESD susceptible part, or no more than 20 volts if the most CDM susceptible component is not known.
I have been looking into the EM-Aware by SCS to see if it is a feasible alternative to detecting real-time failure points.
Hope that helps.
Thank you for your feedback and your precious advices.