An ESD event is the occurrence of a single electrostatic discharge from any source. Examples of source include ESD simulators, humans and other charged objects. ESD events far below the human threshold for perception—static charges humans cannot see, hear, or feel—can damage static-sensitive components/devices and cause product failure, disruption or financial loss. In work environments, most ESD events are caused by the static generated when people walk, called walking body voltage.
Electrostatic damage to static-sensitive electronic components/devices can occur at any point from manufacture to field service. Damage results from handing the devices in uncontrolled surroundings or when poor ESD control practices are used. Generally damage is classified as either a catastrophic failure or a latent defect.
Catastrophic Failure: When a static-sensitive component/device is exposed to an ESD event it may have caused a metal melt, junction failure or oxide breakdown, permanently damaging its circuitry and resulting in failure. Such failure can usually be detected when the device is tested before shipping. If the ESD event occurs after the test the damage will go undetected until the device fails in operation.
Latent Damage: A latent defect is much more difficult to identify. A device may be partially degraded yet continue to perform its intended function. However, the operating life of the component/device maybe reduced dramatically. This could cause premature systems failure which could prove extremely hazardous and very costly.
