I have a question regarding microscopes used within an EPA.
What are the ESD requirements for these units? Specifically:
I’m not looking for special-case exceptions — just the standard requirements applicable to general EPA usage.
Please reference the relevant ANSI/ESD specifications in your response.
Seon,
Microscopes on a workbench would fall under the requirements ANSI/ESD S20.20 for insulators and/or isolated conductors (section 8.3.1 & 8.3.2). Basically, if the microscope is not grounded, has conductive (metal) components, and can come in contact with your ESD sensitive parts, then it needs to be maintained less than 35 volts. If the microscope cannot contact your ESD sensitive parts or is totally insulative, then the requirements of an insulator apply. This basically comes down to measuring the place where the ESD sensitive item is worked on. If there are no fields in excess of 125 volts/inch (5000 volts/meter) in the area where the ESD sensitive item is worked on, then you should be fine.
So if you are using the microscope like I think you are, namely putting ESD sensitive items on a surface of the microscope for inspection, then the place you place the ESD sensitive item on the microscope should be evaluated. If it is conductive, it should be grounded or kept under 35 volts (this would usually be done by ionization). If the place you put the ESD sensitive items is an insulator, then you would need to measure the fields in this area and make sure they don’t go above 125 volts/inch (5000 volts/meter). If they could go above this, you could mitigate it through ionization or trying a topical anti-stat. You could also use a grounded conductive plate between the ESD sensitive item and the part of microscope that holds the samples.
Greetings of the day to all from India .
Our ESDA expert Andy Sir has well explained and I have nothing special to express further.
Just to enjoy and gain knowledge on this great platform from the ESDA experts, I pen down few lines of my thought.
Universally, there are magnifiers available with ESD safe body which can be grounded or get grounded when kept on a grounded surfaces. Thus , wherever available it is preferred to go in for such items for exclusive use in EPAs.
However, when not available or accidentally using a normal insulative powder coated body magnifiers, one need to follow what Andy Sir has explained in detail.
In general, during the routine CV test it is better to consider it as a Process essential insulator ( per ansi esd s 20 20 2021) and measure the static field voltage to ensure it is less than 125 volts/inch (5000 volts/meter) and in case it is likely to be more it is good to implement ionization process to mitigate the possible damages.
Thank you-Good day