Electrostatic discharges from the human body

Many papers have been published on the subject of electrostatic discharge (ESD) and the effect of these discharges on electronic systems. Only two of these papers have attempted to measure the actual human discharge, the rest being concerned mainly with simulated ESD. A number of simulators are now commercially available to test the susceptibility of equipment to ESD. This paper reports the results of measurements of current peak magnitude and rise time of ESD derived from a charged human body under a variety of experimental conditions. Direct and induced ESD effects are measured using hand-held metal objects in addition to direct discharge from the finger. The influence of multiple earths is investigated and is found to decrease the severity of the ESD both in magnitude and rise time. The authors conclude, as a result of these measurements, that the currently available simulators grossly overestimate the magnitude of ESD, and, as a consequence, involve manufacturers in expensive overprotection of their equipment.