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Calculation for Spark Gap on PCB Layout.

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BABESH

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Hi,
I came to know that spark gaps helps in protecting against ESD,
I seen on one of the PCB, they are with triangular in shape.

Can i get any calculations on the gap Vs ESD voltage it will bypass.

Thanks
Babesh.
 

There was a discussion about this on EDA a month ago. Search for 'spark' and you should find it.

Keith
 

Yes, at 21.II. but I dint bookmarked, but have some IPC from the discussion(?):
IPC7351 Documentations_www.pcblibraries.com/resources/7351.asp...
K.
 

This is a low cost way for protection, but it is not very precise. I would suggest semiconductor and gas tube methods that are well documented and controlled. MOV devices have been around for decades and their cost has drastically declined.

Along with these, doing the wiring routing and shielding properly will add further protection from lightning strike problems.
 

Tubes and semiconductors are great but a first line of defence is a pcb copper spark gap. You want sharp points in the gap. In PADS-PCB copper-shapes won't get sharp points. A component pad (square) will as it is a flashed gerber shape. You can't have the pad rotated 45deg because Pads will draw the pad insted of flashing it. So square pads are offset across the gap so there corners are almost touching, with the smallest gap your board shop will allow (in low voltage applications), say .006inch
 

thanks all for the reply,

In my design i do have the TVS to bypass ESD,
TVS which can handle upto 10kV.

but what the impression i have is that if sudden ESD >20kV strikes my board this spark gap will bypass this ESD, and protect ckt.

From the above replies I understand that PCB spark gap may not help us very well as they are not relaible and are very inconsistance...

Thanks all
--Babesh
 

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