Case Study: ESD Flooring Failure, Incorrect Testing: Always Qualify Your Floor Using ANSI/ESD Test Methods

7 min read, 11 min videos

Note: This information pertains to flooring concerns associated with ESD protected areas (EPAs) in electronics manufacturing and handling. This information is not pertinent to static-control concerns in end-user environments. If your interest focus is on ESD flooring for data centers, server rooms, 911 call centers, school labs, networked offices, FAA flight towers, communication rooms or telecommunication areas – go to this page for technical articles

ANSI/ESD S20.20 provides specific test methods to qualify and evaluate ESD flooring materials. Other methods – such as European test methods or NFPA methods – yield results that differ from and are incompatible with ANSI/ESD test results. While a material may pass European or NFPA tests, the floor may still fail to comply with S20.20. The only way to ensure that your ESD floor complies with relevant standards is to test according to test methods in S20.20. For best results, require tests performed by an independent lab.

THE GIST: ESD Flooring Failure, Incorrect Testing 

  • An improperly installed vapor barrier will not adhere to the subfloor.
  • When the bond between vapor barrier and subfloor fails, the tiles will lift.
  • Ensuring a strong bond requires due diligence:
    • Take a core sample
    • Perform a bond test
    • Investigate type of building construction
  • With a good bond, the tiles will not lift – even with a chisel.
  • Get the tile manufacturer involved.
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Background is dark blue with a hand on the right holding a mobile phone which has a newsletter icon on the screen. Several bright newsletter icons appear to be emerging from the phone. On the left in white text it reads "Subscribe to Our Newsletter"

Case Study: ESD Flooring Failure, Incorrect Testing

A military defense contractor (electronics application), trying to meet static-control requirements in ANSI/ESD S20.20-2014, contacted us about a problem they were having with their new ESD floor. They had purchased the new floor under the assumption that it would meet all the requirements of Table 2 in the S20.20 document.

The caller explained that the floor wasn’t meeting any of the requirements – even though the manufacturer had assured them nothing was wrong with the flooring. The client described the floor as a static conductive linoleum sheet floor. Made in Europe, the floor was new to the US market. After reviewing the client’s test data, we agreed to meet with and help them find out why the floor wasn’t doing what it was supposed to do.

Immediately after arrival, we were asked to measure the floor with our Prostat megohm meter.

Ohm meter
Ohm meter

After several tests, we quickly concluded that our meter and theirs were arriving at consistent results. The floor was incapable of meeting any of the S20.20 requirements: it was far too resistive.

The resistance to ground exceeded 1 billion ohms (1.0 x 10E9) – the upper limit in the S20.20 resistance standard.

The building representative was extremely agitated. He knew it would be difficult to shut down the facility and replace the floor. The client admitted that the floor had been a value-engineered substitution, selected late in their project. The manufacturer had guaranteed them that the floor would do everything the originally specified floor was supposed to do.

Under the guidelines in ANSI/ESD S20.20, we use Standard Test Method 7.1 to test for electrical resistance.

Resistance Test - Point-to-Point Rtt
Resistance Test - Point-to-Point Rtt

Upon review of the floor manufacturer’s documents, we discovered the real problem with the floor: the manufacturer’s specifications referenced a resistive properties test method used in Europe. Unlike North American standard test method ANSI/ESD S7.1, the European method tests for electrical resistance using a much higher applied voltage of 500 volts.

According to Ohms Law, higher applied voltages result in lower electrical resistance measurements. In other words, the more voltage you apply, the lower ohms resistance you will see.

Graphic is titled "Voltage and Resistance" with the subtitle "How voltage affects the resistance of an ESD flooring material". The first graphic underneath shows a blue floor tile with boxing gloves (titled "ESD floor's resistance (r)") on the left side. On the right side is a smaller purple rhino (titled "Voltage (v). An arrow points from the rhino back to the tile. The arrow extends beyond the floor tile but is much thinner. The text underneath reads "When voltage is low a material has a much higher electrical resistance". In smaller text underneath it reads "* As indicated in resistance tests performed according to ESDA STM7.1 Underneath this is a second graphic, again with a carpet tile with boxing gloves but a much larger rhino. Again, an arrow is pointing back. This time the arrow that extends beyond the floor tile is much thicker. The text beneath reads "When voltage is high, the same material has trouble resisting (or stopping) the flow of current.
Graphic is titled "Voltage and Resistance" with the subtitle "How voltage affects the resistance of an ESD flooring material". The first graphic underneath shows a blue floor tile with boxing gloves (titled "ESD floor's resistance (r)") on the left side. On the right side is a smaller purple rhino (titled "Voltage (v). An arrow points from the rhino back to the tile. The arrow extends beyond the floor tile but is much thinner. The text underneath reads "When voltage is low a material has a much higher electrical resistance". In smaller text underneath it reads "* As indicated in resistance tests performed according to ESDA STM7.1 Underneath this is a second graphic, again with a carpet tile with boxing gloves but a much larger rhino. Again, an arrow is pointing back. This time the arrow that extends beyond the floor tile is much thicker. The text beneath reads "When voltage is high, the same material has trouble resisting (or stopping) the flow of current.

Following the European test method, the resistance reading appeared much lower than, in fact, it actually was. At an applied voltage between 10 and 100 volts, required by ANSI/ESD S20.20, the resistance measurement was extremely high. Unfortunately for this end user – because no one in their organization had picked up on the test methods referenced by the European manufacturer – they were probably stuck with the floor. The test method was clearly printed on their spec sheet.

There was one other forewarning this client had missed. Despite the reference to a static dissipative value < 1.0 x 10E8 ohms, the manufacturer’s brochure recommended the floor for “areas with sensitive equipment.” Their generic recommendation made no reference – on any of their promotional materials – to electronics manufacturing, EPAs or ANSI/ESD S20.20. There was also no mention of a lifetime static-control warranty.

Banner showing 4 completed ESD flooring installations and the text Staticworx ESD Flooring - Click to View Our Product Range and telephone number 617-923-2000.

Conclusions

  • Only accept materials that have been specified using ANSI/ESD Standard Test Methods: www.esda.org
    • Test for electrical resistance, according to test method STM 7.1
    • Test for walking body voltage (charge generation) according to STM 97.1
  • Always ask for test data from independent labs when qualifying any kind of static-control flooring.
    • Labs like Fowler Labs can perform the full battery of tests needed for qualifying floors to the requirements in ANSI/ESD S20.20.
  • Insist on a lifetime static-control warranty.
  • Always include in your contract a requirement for post installation tests – demonstrating that the flooring meets Method One in ANSI/ESD S20.20 for Personnel grounding.
    • Method One requires ANSI/ESD S97.1 System resistance testing. ANSI/ESD S20.20 confuses many engineers; without reading closely, it’s easy to conclude that the floor merely needs to measure below 1.0 x 10E9 using test method s7.1-2005. This is a fallacy.
  • The floor must also meet charge generation requirements. For electronics facilities, the floor may not generate more than 100 volts of static electricity; for Class-0 electronics the upper limit is 10 volts.

You might also take a look at this video for further understanding. Static dissipative versus conductive:

Background image shows an illustration with a close up of an ohmmeter. The title Conductive versus Dissipative Flooring: Does It Matter? is displayed in bold white text against a rectangle of dark blue grey at the bottom of the image and just above is the Staticworx logo.
Play Video about Background image shows an illustration with a close up of an ohmmeter. The title Conductive versus Dissipative Flooring: Does It Matter? is displayed in bold white text against a rectangle of dark blue grey at the bottom of the image and just above is the text "Static Shorts with Dave Long - Right from my Den" and the Staticworx logo
Background image shows an illustration with a close up of an ohmmeter. The title Conductive versus Dissipative Flooring: Does It Matter? is displayed in bold white text against a rectangle of dark blue grey at the bottom of the image and just above is the Staticworx logo.
Play Video about Background image shows an illustration with a close up of an ohmmeter. The title Conductive versus Dissipative Flooring: Does It Matter? is displayed in bold white text against a rectangle of dark blue grey at the bottom of the image and just above is the text "Static Shorts with Dave Long - Right from my Den" and the Staticworx logo
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Further Resources

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About StaticWorx, Inc

All StaticWorx posts are written by our technical team and based on industry standards and specifications, test data, independent lab reports and other verifiable data. We provide ESD training and offer CEU credits to architects. If you’re interested in an ESD training session or our architects’ ESD workshop, give us a call: 617-923-2000.

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StaticWorx high-performance static-control floors protect electronic components, explosives, and high-speed computers from damage caused by static electricity. ESD flooring is part of a system. Choices should always be based on objective, researched evidence. When you partner with us, we look at all possible items that may need to integrate with the floor, and, focusing on your goals and objectives, help you find the right floor for your application.