Electrostatic Discharge (ESD) Protection

Most plastics are electric insulators and tend to accumulate static electric charges. This build-up can lead to electrostatic discharge (ESD) and damage electronic components or other sensitive materials. However, ESD can be managed by leveraging properties like conductivity and its inverse, resistivity.

Resistivity is a measure of the resistance to the flow of an electric current and is measured either as a surface or a volume phenomenon. Surface resistivity is expressed in ohms per square (Ω/sq) and is measured at the surface of a material, usually at room temperature¹. A conductor is a material with a surface resistivity less than 10⁵ Ω/sq, while an insulator is a material with a surface resistivity greater than 10¹³ Ω/sq.

Since conductors have a low surface resistivity, they excel at transferring electric charge between materials. This ability can be beneficial in electromagnetic interference (EMI) protection and some ESD protection applications; however, it can increase the risk of transferring charge from exterior objects back into sensitive materials, rendering strong conductors less suitable for specific ESD protection applications. For these applications, it is better to use electrostatic-dissipative materials, which have a surface resistivity between a conductor and an insulator, usually between 10⁶ and 10¹² Ω/sq. These materials can be produced by filling an insulator such as plastic with a conductive material such as carbon black, which disperses static and prevents build-up while reducing the risk of conducting exterior charge back into materials.