Video: How to Meet ANSI/ESD S20.20 with ESD Flooring
**The ANSI/ESD S20.20 standard has changed. For up-to-date information, please see our new video: Qualifying an ESD Floor – Resistance and Charge Generation.
For detailed written information, read our article “Qualifying ESD Flooring” published in the August 2019 issue of In Compliance Magazine.**
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Qualify ESD Flooring the Easy Way: Testing Static-Safe Flooring for Electronics Handling and Manufacturing Environments ANSI/ESD S20.20-2007, “Protection of Electrical and Electronic Parts, Assemblies and Equipment provides administrative and technical requirements for establishing, implementing, and maintaining an ESD Control Program to protect electrical or electronic parts, assemblies, and equipment susceptible to ESD damage from Human Body Model (HBM) discharges greater than or equal to 100 volts.
Visit our Learning Center for more information on ESD Standards and Tests.
Hi, I’m Dave Long from StaticWorx.
In this sequence we’re going to talk about what’s actually involved when you’re tasked with putting in a floor that
meets ANSI ESD s20.20. I get called probably once a week by people asking me what the resistance of the floor should be in ohms so they can meet 20.20.
When you’re looking at flooring, you have to think about how am I going to use the flooring, what are people going to wear when they walk on the floor. The ANSI document actually recognizes the fact that flooring is part of a system. It doesn’t operate by itself.
So if you look at Table 2 in the ANSI document, you will actually see right above the table two methods for qualifying a floor that technically meets the requirements of that document.
Method 1, which is the easy way to meet ANSI 20.20, is to have a person put on static-control footwear, take an ohmmeter, hold one of the leads in their finger, attach the other lead to ground while they’re standing on the static-control floor and take a measurement of the ohms resistance of their body, their footwear, the floor, the adhesive, if the flooring uses adhesive, the ground connection, and if that reading is less than 3.5 times 10E7–which is the same thing as 35 million ohms–if it’s under that number, then your system meets ANSI 20.20.
So it’s not just about the floor, it’s about the system.
What I have in my hand is what we call a heel strap, a conductive foot strap. What this is is a carbon loaded rubber cup that attaches to the back of your shoe. It actually goes over your heel. These velcro pieces go on the top of your foot and then this tucks inside your sock and what this does is acts as an electrical bridge between the skin on your body and the conductivity of the floor because keep in mind, the shoes you’re wearing in all likelihood are insulative. That means they’re not going to allow static electricity to drain from your body to the floor. So the heel strap is the bridge that allows that to happen.
So another way of looking at a heel strap is this is a portable wrist strap. The heel strap is a very important component in any ESD program because as I said earlier, we’re not really looking at a static-control floor by itself. We’re looking at it as a system and that system includes footwear. Heel straps like this are relatively inexpensive. There are a number of manufacturers around the world. There are a couple of links on our website.
So when you qualify the floor based on s20.20, you want to be looking at the footwear, the floor, and the interface.
There is another qualification method. We call it method 2. Method 2 requires you to go to some fairly extraordinary lengths and when you go to do your quarterly or twice a year audits now you need to have someone in a place where they have the equipment and they know how to use the equipment which means you’re probably looking at engineering
personnel doing the qualifications as opposed to anyone, including the maintenance department, going out on the floor and putting down an ohmmeter, holding it between their fingers and pressing a button.
In the qualification stages I would suggest that you look for one order of magnitude under that 3.5 x 10E7, knowing that you’re going to have circumstances occurring like the floor gets dirty, someone puts a wrong wax on the floor, that the heel straps aren’t tucked in properly.
You want to build your system around the potential mistakes that can occur.
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