ESD試験器の接触放電に対するIEC規格理想電流波形の人体気中放電に基づく検証

抄録

In 1989 the International Electrotechnical Committee (IEC) adopted contact discharge testing of an electrostatic discharge (ESD) generator to reduce the variations in air discharge test results, and specified in IEC 61000-4-2 only the four waveform parameters (the rise time of the first peak current, the current value of the first peak, the current values at 30 ns and at 60 ns), also schematically showing a typical contact discharge current waveform. In 2008 the IEC offered an ideal contact current waveform along with a Heidler’s formula that allows calculating the current waveform from an ESD generator, whereas its scientific rationale is not provided. In this paper, human air discharges at charging voltages of ±8 kV are measured to validate the IEC ideal current waveform through waveform comparison. The result shows that measured current waveforms from human air discharges greatly change depending on the spark length, and the current waveform does not have the second peak in addition to the falling edge of the first peak seen in the IEC ideal current waveform. Nevertheless, there exists the first rising peak current with a rise time that satisfies the IEC standard, coming closest to the IEC ideal current. Furthermore, air discharge currents having almost the same rise times as those of the IEC ideal currents at different test voltages, which are calculated from an equivalent circuit previously proposed for human air discharges based on the IEC standard, are shown to be moderately consistent with the ideal current waveforms and also to meet with all the IEC specified requirements. This finding supports the validity of the IEC ideal current waveform in a sense that the IEC specified waveform reflects natural phenomena of human air discharges.