静電気放電試験器の気中放電モードにおける保持出力電圧の測定法と検証

抄録

The International Electrotechnical Commission (IEC) 61000-4-2 specifies an air discharge testing method as a mandatory electrostatic discharge (ESD) immunity test, since an actual charged human accompanies air discharges. In addition, the IEC standard also prescribes the holding time of over 5 s where the decrease of the discharge electrode voltage due to current leakage, prior to the air discharge, should not be greater than 10%, whereas no measurement method has been specified. In this study, a method is proposed for measuring the holding output voltage of an ESD generator in air discharge mode with a commercially available high voltage probe connected through a wire to a small metal sphere for contact discharges and air discharges. The proposed method consists of two steps that measure the peak voltages for contact discharge with a test voltage and for air discharge with the same test voltage but in 5 seconds after the trigger. The ratio of the latter peak voltage to the former one provides the ratio of the holding output voltage to the test voltage. The measurement principle is shown theoretically using the equivalent circuits for a measurement setup, and is validated numerically and experimentally. To demonstrate the effectiveness of the presented method, measurements of the holding output voltages for two defective ESD generators collected from the market are conducted in comparison with a normal ESD generator.