NEW APPROACHES FOR MEASUREMENT OF STATIC ELECTRICITY TOWARD PREVENTING ESD

Serious failures of the latest electronic equipments occur easily due to electrostatic discharge (ESD), which can be caused frequently by th e electrification phenomena of human-body walking on the floor. The nu mber of the above damaging incidents has significantly been increasing with an increased use of integrated semiconductor elements with lower operation power. The most effective measures against the ESD consist in preventive ones, which are to obtain dynamic behaviors of the elect ric charge before the ESD happens, thereby preventing the charge accum ulation. From this point of view, this paper describes new approaches for measurement of the static electricity directed toward preventing t he ESD. First, a two-dimensional measurement method for visualizing ch arge distributions is described. This principle is based on visualizin g the potential distribution induced in the array electrodes from the electrostatic fields. For showing usefulness of the visualization meas urement, a prototype was built and attempts were made on the visualiza tions for the static electricity distributions of charged bodies. Seco nd, a potential calculation of the human body charged by walking on th e floor is described. A model was shown for analyzing the human-body p otential on the floor, and the theoretical equation for describing the potential attenuation process was derived in the closed form in the L aplacian transformation domain. In order to obtain the typical half-li fe of the human-body potential, numerical computations were performed using a reverse Laplacian transformation. The experiments were also co nducted for confirming the validity of the computed results. Finally, a new method is described for estimating dynamic behaviors of the occu rrence charges of the human body electrified by walking-motions. Stati stical measurements of the charges and potentials were made for the fu ndamental walking-motions specified here. The pace transitions of the potentials due to continuous walking and stepping were also measured a nd their results were explained from the electrification properties fo r the fundamental walking-motions.