Discussion: Figure 1 shows one frame of a short video taken of sequential contact discharges from an ESD simulator. The measurement was made in a fashion similar to that shown in Figure 2, although the ESD simulator used to generate the data for this article was not the one shown in Figure 2, but a different one measured at a later time.

In Figure 2, the ESD simulator is discharged in the contact discharge mode into the Horizontal Coupling Plane, HCP, of an ESD test table through a Fischer Custom Communications F-65 current probe. To get maximum current, the simulator ground lead was connected to the HCP (as done in the ISO10605 ESD standard) rather than the ground reference plane on the floor to which the simulator ground lead is normally attached for IEC testing. The test was performed near the edge of the table for convenience, so the waveform will not be exactly a calibration waveform, but similar. The object was to look at variations from discharge to discharge.



Figure 3 is identical to Figure 1 except if you click on Figure 3 a Flash video should play in your browser. You can see significant variation from discharge to discharge. The scope was sampling at 8 GSa/sec, so the variation was not due to sampling errors. That sampling rate gives 400 samples per horizontal division, more than adequate for this test.