Electrostatic Discharge, or ESD, is defined as the transfer of charge between bodies at different electrical potentials. If you scuff your feet as you walk across a carpet, electrons move from the carpet to you, leaving you with excess electrons. Touch a door knob and ZAP! The electrons move from you to the knob. You get a shock, at a minimum of 3,000 volts (the threshold of human feeling)!
The kind of ESD shock you feel may also be responsible for damaging electronic components in many computers and telecommunications systems. While it takes an electrostatic discharge of 3,000 volts for you to feel a shock, much smaller charges, well below the threshold of human sensation, can and often do damage semiconductor devices. Many of the more sophisticated electronic components can be damaged by charges as low as 10 volts.
How it happens
Static electricity is defined as an electrical charge caused by an imbalance of electrons on the surface of a material. Once the charge is created on a material and it remains at rest on the material, it becomes an “electrostatic” charge. An ESD event is a rapid transfer of charge (electrons) from one object to another in an attempt to become electrically neutral.
Electrostatic charge is most commonly created by the contact and separation of two electrically nonconductive materials. The amount and type of charge (positive or negative) depends on the materials involved.
CONTROLLING ESD
The following are ways of managing ESD.
- Antistatic mat
-
Alternatively referred to as a grounding mat, an antistatic mat is a floor or table mat used to help reduce the risk of electrostatic discharge while working on a computer or other electrostatic sensitive device. The picture shows an example of a laptop being repaired by a technician. The blue mat under this laptop is an antistatic mat.
CAUTION:
All computer boards are sensitive to electrostatic discharge. To avoid possible damage, handle all static-sensitive boards, components, and computers at a static-safe work area.
- Wrist strap
-
Wrist strap
Alternatively referred to as an antistatic strap or antistatic wrist strap, a wrist strap is a strap that wraps around the users wrist like a bracelet and has a cord or other connection coming from that bracelet that attaches to the computer. The wrist strap keeps the user grounded, which helps prevent electrostatic damage to a computer or any other electrostatic sensitive device. The picture shows a wrist strap with detachable strap around a wrist.
There are also some anti-static wristbands that work by using a battery in the wristband to create a ground. It does not connect to the computer or antistatic mat in this case since the battery power provides the same grounding as a wired wrist strap.
How to use a wrist strap
Place your wrist in the strap and attach the other end (often using the alligator clip) to a non-painted metal portion of the computer case, antistatic mat, or antistatic workbench. While working on the computer or other electrostatic sensitive device the wrist strap should remain on your wrist.
Leave a Reply
You must be logged in to post a comment.