ESD Systems - Questions And Answers

1. What is the difference between static dissipative and conductive, as used in ESD floors for example? 2. What is the difference between ant-static and static dissipative, as used in gloves? - Elaine, Refraction Technology, Dallas, TX

The difference between static dissipative and conductive is just a classification of how conductive the material is. The range of resistance can be divided into 3 realms, conductive, dissipative and insulative. Conductive as defined by the ESD Association, is any material with a surface resistivity below 1x10^5 ohms/square or with a surface resistance less than 1x10^4 ohms. Dissipative is defined just above conductive but below insulative. A dissipative material will still conduct charges to a lower or higher potential, just at a slower rate. This controlled rate is what you want to employ when trying to control ESD events (discharges). The high end of the dissipative range is less than 1x10^12 ohms/square for surface resistivity or 1x10^11 ohms for surface resistance. Anything over this range is insulative and will not (under normal conditions) conduct charges. There is a larger difference between anti-static and static dissipative. Anti-static means that something is less prone to triboelectric generate a charge. In other words when to materials come in contact with each other and then are separated, they undergo triboelectric charging. The farther apart they are in the tribo-series, the larger the charge generated between the two materials. When a material is claimed to be anti-static it generally refers to its ability to NOT generate a charge upon contact and separation to the extent that if a charge is generated, it will be less than about 200 volts. Some materials can tribocharge well over 20,000 volts.

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