Determination of characteristics of the discharge current by the human charge model ESD simulator

Abstract

This paper aims at improved reproducibility of the electrostatic discharge current in the electrostatic tester that simulates the electrostatic discharge from the charged human body. The variation of the electrostatic discharge current due to changed testing conditions, including the position relation, is analyzed. The derivation method, where the components of the electrostatic tester, such as the discharge gun and the ground wire, are replaced by electrical parameters, is combined with the method of circuit analysis by simulation. The characteristics of the electrostatic tester are analyzed, and the following situations are revealed. Even though the inductance of the ground wire varies greatly with the testing condition, the main discharge current satisfies the rated value. The initial current is generated depending on the switch structure of the tester, and is caused by the stray capacitance around the discharge current limiting resistor. The proposed circuit model exactly represents those characteristics of the electrostatic tester. By combining the proposed circuit model into the EDA (electronic circuit design automation) system, the circuit designer can simulate the electrostatic discharge at the design stage. This makes it easy for the designer to interpret the characteristics in the electrostatic testing, and can reduce the trial-and-error effort. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80(10): 49–57, 1997