No.6（2011）12.ESD protection of electronic circuit boards

Toshihiro Takamatsu, Ueno Takeshi, Kobayashi Takeshi

  An EMC test is required for all Electrical equipment. Especially, those items to be exported to Europe must obtain CE certification under the EMC directive. An electrostatic discharge immunity test (IEC/EN/JISC61000-4-2) is one of the EMC tests.
 Corrective measures must be taken if the product does not pass the EMC test. Failures caused by ESD may take a long time to repair making it necessary to understand the phenomenon of electrostatic discharge.
 A method has been established to measure the waveform and transmit a static waveform in an electronic circuit board. In order to use this method in an electronic circuit design process, the ESD simulation model must be effective.
 The authors found through experiment that the EDS wave frequency is between 250MHz to 300MHz. To suppress crosstalk caused by EDS, components such as capacitors, inductors, varistors and zener diodes are useful. We evaluated that those components were effective against EDS when an electronic circuit board was running under a 10MHz clock.
 Of those components, only the zener diode can be used in a high speed circuit board in term of signal integrity.

Keywords
Electrostatic wave form, Electrostatic discharge immunity, Frequency response, EMC prevention component

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