The ESD current waveform influenced by the different shape and position of the ground strip
The ESD current waveform influenced by the different shape and position of the ground strip (Total Y offset 70%, Total X offset 20%)
It can be seen from the above figures that when the ground strip is in winding, that is the inductance is very large, the waveform (Black) vibrating during the decay period. When the ground strip is in straight line, the waveform (Blue) is very similar to the waveform proposed by IEC61000-4-2 standard. When the ground strip is in other shape and position, the waveform is also influenced by the inductance.
Reference:
ESD Test Report (Jiusheng Huang, UMR, 2002)
Effects of the ESD field on the waveform of digital electronic system
Test the ESD Susceptibility of Computer
Electrostatic Discharge Susceptibility of Computer Peripherals