A study on long duration electrical stress induced by electrostatic discharge on wearable devices

In real environment wearable devices are used, ESD occurrence conditions are considered to be different from previous test methods because wearable devices are usually held by users in their body. In our previous study, we measured electrical stress induced by ESD from a charged human's fingertip to grounded objects on wearable devices held in charged human. From these results, shapes of the induced voltage waveforms, their durations, and amplitudes are quite different in wearable device's circuit structure. Especially, durations of the induced voltage waveforms at high impedance line are very long around ten or hundred microsecond order. The shape of these induced voltage waveforms have single peak and exponential decay curve after 1st peak. As this long duration has possibility to keep circuit high-level long time, it is considered to be one cause for malfunctions. Therefore, in this study, we considered characteristics and generation mechanism of the long duration induced voltage by additional experiments.