Electrostatic discharge (or ESD) is the sudden flow of electricity between two electrically charged objects caused by contact, a short, or dielectric breakdown—it is commonly experienced when touching a metal doorknob after walking across a carpeted floor. Though ESD is usually a relatively low-voltage occurrence, lightning is also an ESD event. And even small discharges can be enough to damage or destroy sensitive electronic equipment in a manufacturing process.
Protection against electrostatic discharge can be provided through a number of methods. Creating an electrostatic protective area (or EPA) is the most comprehensive and effective method, consisting of several smaller measures taken together. The general principle of an EPA is to remove highly charging materials from the immediate vicinity and to ground workers and conductive materials.
A key component of an EPA is the use of conducting wrist-straps and foot-straps by workers, to prevent high voltages from accumulating on their bodies. Anti-static floor mats or conductive materials can also reduce or eliminate voltage. Where these wrist-straps, foot-straps or floor mats are impractical or impossible to use, humidity control and ionized air can help neutralize electrostatic charges.
The use of ESD-safe manufacturing equipment and other devices is also recommended. Specially designed, electrically-grounded tools should be used for assembly processes. Anti-static brushes with unique bristle and handle materials are available for cleaning and scrubbing. ESD-free packaging materials can be used to protect components between processes or completed products for handling and shipping.
Many ESD-sensitive electronic components and assemblies are handled with automated equipment. Due to the dielectric nature of industrial electronics, electrostatic buildup cannot be completely prevented, making ESD prevention important in these processes, as well. Where components come into contact with equipment surfaces, or when they are connected with other conductive parts of the product itself, grounded static-dissipative materials are recommended. Static dissipative materials have very low electrical conductivity and will slowly conduct static charges away from ESD-sensitive parts.
- The Prevention and Control of Electrostatic Discharge http://www.minicircuits.com/app/AN40-005.pdf
- Electrostatic Discharge http://en.wikipedia.org/wiki/Electrostatic_discharge
- ESD Brushes & Static Electricity http://www.gordonbrush.com
- Prevention of Electrostatic Discharge Damage http://www.juniper.net/techpubs/en_US/release-independent/junos/topics/reference/safety/ex-series-prevent-esd-damage.html