| （英） |
With the high speed and low voltage operation of ICs, serious malfunction of high-tech information devices is known to be caused by electrostatic discharge(ESD) events that a charged human-body produces. In order to elucidate the generation mechanism of human ESD events, we previously measured discharge currents due to collision of a hand-held metal piece with a 6-GHz digital oscilloscope, and then proposed an equivalent circuit model to calculate the discharge current. This allowed us to derive a discharge voltage across the spark gap, which can not basically be measured, and demonstrated the occurrence of arc discharges following the spark. It was also found that at charge voltages bellow 600 V the estimated breakdown field from the discharge voltage is almost kept constant (2×107 [V/m]) regardless of the different approach speeds of the metal piece. In this study, we have investigated to what extent numerical calculation methods affect the estimated breakdown field in calculating the discharge voltage waveform from the equivalent circuit model. Measurement of the discharge current has been made with a wideband digital oscilloscope (bandwidth: 12 GHz; sampling frequency: 40 GHz), and discharge voltage waveforms have newly been derived from both the inverse Fourier transform and convolution integral. As a result, we have found that although the both equations are mathematically equal, the calculated results obtained by the both methods are rigorously different, while there is in good agreement between the waveforms of the discharge voltages just after the spark. It has also been confirmed that the estimated spark length is 20～30 [m] and the breakdown field is 2～3×107 [V/m] at a charge voltage of 600 V. |