What You Should Know Before Using ESD Laminate and Continuous Monitors

There are all kinds of variations and combinations of ESD Laminate and Continuous Monitors used by companies with ESD Programs.. There are some key factors that you need to be aware of if you intend to use ESD Laminate together with a continuous monitor that will monitor the worksurface connections.

It’s important to note that continuous monitors don’t monitor the status/condition of the outer surface of an ESD workstation. The continuous monitor monitors the connection between groundable points on the worksurface (often snaps), not the Resistance to Ground (RTG) of the surface itself. The RTG measurement must be taken separately, per ANSI/ESD TR53-01-18 – Compliance Verification of ESD Protective Equipment and Materials (Pages 6 and 7).

The basic technology is that the monitor applies a low test voltage to the scrim layer in the worksurface. Because the test voltage is so low, the resistance of the scrim layer of the mat must also be low so that the test voltage can complete a circuit of the scrim layer, worksurface connections (snaps) and ground cords. Completing that circuit indicates that the worksurface is electrically connected. The goal is to have the worksurface circuit fail because of a bad connection, not because the scrim layer resistance was too high.  As mentioned earlier, testing the combination of the outer layer and the scrim layer together (RTG) is a separate test.

When choosing a continuous monitor and worksurface combination that will work together it is important to consider the following:

  • Does the worksurface have a separate scrim layer? (vs. a homogenous mat material)
  • Does the continuous monitor spec sheet note the resistance limit of the scrim layer required for the monitor/worksurface alarm system to pass?
    • See the excerpt below from the SCS 724 Continuous Monitor Technical Bulletin – https://www.descoindustries.com/PDF/724-Workstation-Monitor-User-Guide.pdf
      Red Worksurface LED (M) This indicates that a high resistance condition (> 3.7 Megohms) exists across the conductive layer of theworksurface and/or the ground connections. Check the worksurface, ground cords and their connections for continuity. Note the audible alarm may also sound if enabled.”

What this means is if the resistance of the mat scrim layer is greater than 3.7 Megohms then the continuous monitor mat alarm would alarm for a high resistance condition even if the grounding hardware connections to the worksurface were intact. There are other SCS monitors available that will monitor a scrim layer with a resistance as high as 5 x 108.

In summary, it’s critical to know both the upper limit of the “pass” condition of the continuous monitor and the construction of the worksurface material (does it have a scrim layer and if so what is the resistance of the scrim layer?)

ESD Laminate requires extra attention when being considered for use with a continuous monitor for the following reasons:

  • Laminate material is rigid, which makes it more difficult for grounding hardware to make a good contact with the scrim layer.
    • Consider abrading the outer, decorative surface to expose the scrim layer for better contact. Consider a flat bottom drill for this process.
  • Most importantly, perform a test on the resistance between two points on the worksurface to determine if the resistance meets the requirements of the specified monitor (for the SCS 724 that requirement is less than 3.7 Megohms – 3.7 x 106 ). We recommend using an ohm meter with a test voltage similar, if not identical to the test voltage used by the continuous monitor. We recommend performing this test before the purchase/installation of any number of continuous monitor/worksurface combinations.

4 Comments

  1. Ed
    Permalink

    We have a grounded ESD laminate countertop in a workstation and are considering whether we should be doing continuous monitoring of the work surface in addition to wrist straps. For the work surface, there is no provision for a snap-on monitor cord that is often used with mats. We don’t plan on a mat over the countertop because the countertop is designed to provide ESD protection. The work surface, which is about an inch thick, has a scrim layer between the laminate and the substrate, and has a ground post towards the back of the countertop. On the underside of the countertop, the post has a screw which a facility ground wire attaches. On the top, the post becomes a quarter-size metal flat at the the surface. The work surface measured resistance is 10 MegOhms. Do installations with ESD countertops typically run a continuous monitor for the countertop? If so, what product (analogous to the mat monitor snap on cord) is used to run from the countertop to a monitor unit, and how is it installed on/in/through the countertop?

    Thanks

    Reply
    • scsstaticcontrol
      Permalink

      Hi Ed, thank you for your comment and interest in continuous monitoring. I have passed your comment on to our sales team who have got back to you via email. Please do let us know if you don’t receive it for any reason.

      Reply
      • ed
        Permalink

        Have not received anything from your sales team.

      • scsstaticcontrol
        Permalink

        Sorry to hear you haven’t received our email. I have provided an email below that you can contact. In general, we do not recommend pairing continuous monitors with laminate. We have seen customers experience issues with ensuring the grounding hardware maintains a good connection with the scrim layer, which the monitor would be continuously looking for.
        Due to this, SCS dual-wire monitors are mostly designed and tested for use with mats. Worksurface matting is easier to ground, troubleshoot and maintain its electrical properties. If you contact Service@StaticControl.com we can discuss what solutions are available to you.

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