Electrostatic discharge materials are plastics designed to reduce static electricity to eliminate sparking that can cause ignition of flammable substances or protect electrostatic-sensitive devices. These plastics come in varying degrees, such as antistatic and static dissipative. Understanding antistatic vs. static dissipative plastics will help you choose the right material for your application.
A build-up of static electricity can occur when there is sliding or rubbing of a material. When this happens to an insulating material, like plastic, the charge tends to remain in the localised area of contact between the materials. This electrostatic voltage can then be discharged via an arc or spark when the material comes in contact with another part at a sufficiently different electrical potential – such as a microcircuit or other equipment.
Electrostatic discharge (ESd), which is the sudden flow of electricity between two electrically charged objects can have catastrophic effects. An electrical spark is especially dangerous in environments that contain flammable liquids, solids, or gasses, such as an underground coal mine. Another common casualty of ESd are sensitive electronic components. Some micro-electronic parts can be destroyed or damaged by ESd as low as 20 volts. The consequences of ESd damage to an electrical component range from faulty readings to permanent damage, all of which result in equipment downtime and costly repairs. Antistatic and static dissipative plastics are used to minimize the risk of ESd and reduce breakdowns.
Conductive thermoplastics are categorized based on their surface resistance, which measures how easily an electric charge can travel across the surface of a substance. Static dissipative plastics have a surface resistance that is between an upper and lower limit, for example, 10^4 to 10^6 ohms/sq and allow electrical charges to dissipate generally within milliseconds. Static dissipative materials allow the charges to flow to ground more slowly and in a more controlled manner.
Anti-static materials have a surface resistivity that is less than a given value. For example, in underground coal mines in Australia, materials must have a surface resistance of < 300 x 10^6 Ohms/sq (in addition to being flame retardant). Anti-static plastics suppress initial charges and prevent the build-up of static electricity.
Dotmar has both Antistatic and Static Dissipative materials that we can also custom machine into finished parts.
Polystone M Flametec is an antistatic and flame-retardant material that is approved for use in underground coal mines in Australia, i.e. meeting the requirements of MDG3608.
The Semitron ESd range provides a range of Static Dissipative materials with values that include 10^4 to 10^6, 10^6 to 10^9, & 10^10 to 10^12 Ohms/sq
