Experimental verification of spark-resistance formulae for micro-gap ESD in parallel disc electrodes

Abstract

Micro-gap electrostatic discharge (ESD) events due to a charged human body cause serious malfunction in high-tech information devices. For clarifying the mechanism, it is indispensable to grasp the spark properties of micro-gap ESDs. For this reason, two types of spark-resistance formulae proposed by Rompe-Weizel and Toepler have often been used so far to explain the spark process, however, the verification and applicability of these formulae still remain unknown. We previously measured spark currents from a human volunteer with charge voltages of 200 V or 2000 V in order to investigate which spark-resistance formula can explain the spark process. The result showed that the behavior of sparks from 200 V and 2000 V charged human can well be represented by the Toepler's and Rompe-Weizel's formulae, respectively. In this study, a new measurement setup for spark currents, which are difficult to be directly measured due to the charge neutralization through the spark channel, was developed by using parallel disc electrodes. The setup allows to simply estimating the spark current and the corresponding spark voltage from the measured discharge currents. From this setup, we confirmed that spark currents are almost identical to discharge currents from the disc electrodes with charge voltages of 500 V and 4000 V, to reveal that the Toepler's and Rompe-Weizel's formulae are applicable to predict the dynamic behavior of micro-gap sparks at charge voltages of 500 V and 4000 V, respectively, despite the fact that the spark lengths obtained from the most commonly used spark constants do not agree with the measured spark lengths. This finding supports our previous study.