Physics:Electrostatic discharge materials

Conductive ESD bag with a network card inside

ESD shoes

Electrostatic discharge materials (ESD materials) are plastics that reduce static electricity to protect against damage to electrostatic-sensitive devices (ESD) or to prevent the accidental ignition of flammable liquids or gases.

Materials

ESD materials are generally subdivided into categories with related properties: Anti-Static, Conductive, and Dissipative.

Ohms Per Square	< 10−3	10−3 to 1	1 to 103	103 to 106	106 to 109	109 to 1012	> 1013
Material	Metals	Carbons	Shielding	Conductive	Static Dissipative	Anti-Static	Insulative
Description		Carbon powders and fiber		No initial charge. Provides path for charge to bleed off. Typically black color.	No or low initial charge. Prevents discharge to or from human contact	Initial charges are suppressed. Typically pink color.	Insulators and Base Polymers. Not an ESD material

Note that the sheet resistance quoted above depends on the thickness of the layer of material, and the value is the resistance of a square of the material for a current flowing from one edge to the opposite edge.

Conductive

Conductive materials have a low electrical resistance, thus electrons flow easily across the surface or through these materials. Charges go to ground or to another conductive object that the material contacts.

Dissipative

Dissipative materials allow the charges to flow to ground more slowly in a more controlled manner than with conductive materials.

Anti-Static

Anti-static materials are generally referred to as any material which inhibits triboelectric charging. This kind of charging is the buildup of an electric charge by the rubbing or contact with another material.

Insulative

Insulative materials prevent or limit the flow of electrons across their surface or through their volume. Insulative materials have a high electrical resistance and are difficult to ground, thus are not ESD materials. Static charges remain in place on these materials for a very long time.

See also

• Antistatic device
• Electrostatic discharge
• Electrical resistivity and conductivity
• Velostat

Further reading

• The Wiley Encyclopedia of Packaging Technology; 1st Edition; Kit. L. Yam; John Wiley & Sons; 1353 pages; 2009; ISBN:978-0-470-08704-6.
• Plastics Additives Handbook; 6th Edition; Zweifel, Maier, Schiller; Hanser Publications; 1222 pages; 2009; ISBN:978-1569904305.
• Handbook of Conducting Polymers; 3rd Edition; Skotheim and Reynolds; CRC Press; 1680 pages; 2007; ISBN:978-1574446654.
• Conductive Polymers and Plastics: In Industrial Applications; 1st Edition; Larry Rupprecht; Elsevier; 293 pages; 1999; ISBN:978-0815516569.
• Plastics Additives and Modifiers Handbook ; 1st Edition; Jesse Edenbaum; Springer; 1136 pages; 1992; ISBN:978-0442234508.
• Metal-Filled Polymers: Properties and Applications; 1st Edition; S.K. Bhattacharya; CRC Press; 376 pages; 1986; ISBN:978-0824775551.

External links

• http://www.esda.org - ESD Association
• ESD packaging advice - Intel
• Workmanship Manual for Electrostatic Discharge Control - NASA

de:Elektrostatische Entladung#Klassifikation der Werkstoffe