The term or label ESD Safe has been used for some time now by many primary manufacturers of ESD control products, and others where it may be a small part of the products design. Like the term antistatic, it is often incorrectly used. How do you know if it really is “safe” for use in your EPA? Just labeling something ESD Safe doesn’t give you the technical information you need to make an educated decision for your ESD Control Plan and EPA. One man’s ESD Safe can be another’s ESD threat. When reviewing years of ESD Association Standards and Technical Reports, there is only one reference to the term ESD Safe. This may have accidentally been misused, as it was in reference to shelving and no other area ESD Control Item in the EPA.
When selecting and evaluating suitable ESD Protective items for you EPA, many of these will already be listed in Technical Requirements (ESD Control Item) tables of ANSI/ESD S20.20-2021. For example, ESD Worksurfaces, ESD Flooring, etc. In this case you choose them based on them meeting the maximum Rtg or Rtt requirement. However, there may be applications that are not in the S20.20 Technical Requirements or fall under an ANSI/ESD S541 Packaging resistance category. For example, ESD tapes, gloves, foams, etc. In this case, your goal is to specify a product that is <1 X1011 at the highest. Then you can be assured they fall into the category of ESD Protective. Some of the important factors to consider in the decision making process should include: is there an ESD Association Standard test procedure for measurement and qualification, what is the HBM and CDM Class of your most sensitive device, the proximity of the item to the device it will be used at, does it need to be grounded, is it for cleanroom use, permanency or type of the ESD protective properties, or the isolated conductor rule, etc.? Also, if the item is an insulator and does not violate the Rules for Insulators, you may not need it to be ESD Protective?
Here are some examples of products you should/might not be concerned about and why:
• ESD Protective Gloves – for example, is a Nitrile glove naturally dissipative to some degree or is it made that way with a more permanent ESD additive? Well, it can be both. Whether Nitrile or made with a dissipative additive, it may be <1 X 1011. But, if it needs to be grounded or grounding something you are holding like a tool, tweezer, etc., then it should be <1 X 109, and will most likely need to be made with an additive. Do you need to test your personnel grounding devices (wrist straps, foot grounders) while wearing Nitrile gloves? If so, the glove needs to be more conductive, and you may need test equipment capable of allowing this.
• Metal Hand Tools – tools like cutters, pliers, tweezers, screw drivers, should have ESD Protective Grips or they could be an isolated conductor even when holding them in your grounded hand.
• AC Powered Tools, Soldering Irons, De-Soldering, Heat Guns – a plastic case/enclosure of these tools may only need to be ESD protective if they violate the Rules for Insulators. The metal tip touching ESDS devices shall have <10 ohms of resistance to ground.
• Computers/Keyboards – most modern LCD screens are not static generating unless they are not shielding (best to measure with a static field meter). Follow the Rules for Insulators for keyboards.
• ESD Brushes – you certainly want to replace your standard poly brushes with an ESD Protective version if they will be touching an ESDS device. In many cases, something static dissipative is all you need. But if they are going to be used with solvents, something more conductive or carbon loaded will last longer. If the bristles are <1 X 109 you would want the handle to be groundable as well.
Please contact Desco with any questions you may have or with a specific application.