STUDIES ON ULTRA HIGH SPEED ELECTROSTATIC DISCHARGE PHENOMENA

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The aim of this research is a fundamental study of very high speed electrostatic discharge (ESD) phenomena which have never examined in details although ESD is already very well-known. Especially, a very fast rise-time pulse ESD with a very short discharge gap length has been studied in this research. A uniformly corona-charged FEP or PTFE teflon sheets (film) with thickness of 25, 50, 100 or 200 mum is located on a flat ground plate and a sphere electrode connected to the ground plate with an earth wire approaches to the charged film with a constant velocity. When the electrostatic discharge occurs between the film and the electrode, a current-transformer (CT) can detect the discharge current through the earth-wire and the discharge current wave form is recorded by the transient digitizer whose sampling rate is 100GS/s and the frequency range is 500MHz. A whole system is controlled by a personal computer and all data are stored in a floppy disk. When the film is charged positively, it is found that the discharge gap length for the film is rather larger than that for the negatively charged film. On the other hand, peak current value and total-moved charge are a little bit small. Initial charge supply tests by beta-ray irradiation or UV-irradiation was found to be not so effective. Some noise generation by ESD is also examined. ESD between the dielectric films (one is charged) was also tested where the reduction of the gap length is roughly 30% and the reduction rate of the current etc. very large, that is, the current is only one third or one forth.