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Suggestions needed for PCB static electric arcing problems

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jmartens1978

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I have a project that I am working on and would like some input from anyone that has some knowledge on High Voltage Arcing on PCBs.

Problem: I have a PCB that is enclosed in a plastic enclosure that has metal pins and switch that extend to the outside of the enclosure. Static electrical shock is hitting those pins and switches and the high voltage from that shock appears to be traveling through the circuit and taking out ICs. When I transferred the shock into the pins I noticed that there was arcing from trace to trace and trace to pads trough out the PCB coming from the trace connected to the external switch and pins. The system is a 9v system and the static generator that I used to test the PCB was a Van de Graff generator 10-060. The PCB is extremely compact.

My solution: My solution whether it will work or not is to place ground rings around the external pins on the PCB and the external mechanical switch on the PCB. I am hoping to force the high voltage from the static shock to arc to ground (taking the high voltage straight back to the battery) as soon as it enters the PCB and not travel down the trace to other parts of the circuit. As a back up just in case the static shock does not have a high enough voltage to arc I have MOVs in line with the traces connected to the external parts to hopefully lessen the effects of the higher voltage spike.

I primarily want to force an arc to ground at the point where the high voltage spike enters the PCB. I have little knowledge of high voltage in PCBs.

Questions: Do you think this will work? If not I am open to suggestions. What is the best way to construct the ground ring to guarantee the static shock will arc to the GND ring every time?

Thank you,
Jed
 

HTA

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Hi Jed,

The static voltage is looking for the lowest resistance to ground/earth. If the ground line it closest it should work. This ground line should not be the ground line the circuit +ICs are using, to avoid noise here. Another option I think would be a grounded aluminum film glued inside the enclosure.

Enjoy your design work!
 

tpetar

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Use antistatic protective spray on PCB as first, cheapest and easiest try to solve that.

For permanent solution check or design better grounding.

My every finished and tested PCB is protected completely together with parts, with protective transparent laquier. Some of them I successuly test on direct water splashing.
 
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