Sparkgap

Sparkgap is the cheapest way to do an ESD protection on a PCB without any component. It works very simple, it uses the fact that if voltage is too high it will produce a spark and short the two conductors together.

Here are some examples of sparkgaps designed on PCB :




Design tips

  • Place the sparkgap as close as possible to connectors or where ESD can occur. ESD Wave has to be shorted to ground as soon as possible.
  • Remove coating on the sparkgap. Only plating and copper should remain.
  • 0.2mm space is a good basic spacing value

Formula

V=(3000.P.D)/1000+1350
V is voltage that will cause a spark in Volts
P is the atmospheric pressure in hectopascal (usually 1013 hPa)
D is distance in millimeters

As a rule of thumb : 0.2mm space gives you approximately 2kVolts due to PCB tolerances and atmospheric pressure variation.

See also

References

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