Hi,

I can offer some of the experience we gathered in time.

In the security system business spark gaps are of common use.
On all our connector footprints we use a star shape soldering pad combine to a small coil
(printed on the pcb).
That spark gaps pattern is evenly surrounded with ground plan using a 0.010" clearance gap.
We then make a solder mask opening over that pattern where ever we have a 0.010" gap between
the signal trace and the surrounding ground. (leaving a section of the pattern & the ground
plan to the open air allowing the sparks to fly)

We use this pattern only on the reflow side.  On the wave side we set a 0.020" to 0.025" gap
between the pad and the ground, without solder mask opening to avoid sparking on that side.
Forcing any surge into the spark gap pattern on the reflow side. (bottom spark gaps pattern
are wave soldering hazards)

We have experimented with combine patterns, both on the top and bottom of the PCB, and we
found it after long experimentation to show no improvements.

Sorry I have to disagree with what David Ricketts wrote yesterday. A spark gap does work
repetitively, but still it must be followed by a good protection circuit. (spark gaps are only
the first line of defense)

High voltage surges are part of all our products testing and until now this is the best we
developed and tested.

I hope this will help a bit.

Best regards,

--

Jimmy Blier
CAD Department. (Senior Cad Designer)
P A R A D O X
S E C U R I T Y        S Y S T E M S
Email: [log in to unmask]
Phone:  (450) 491-7444
Fax:  (450) 491-5940


Mary Knouse wrote:

> I would like some information regarding spark caps, and how to design the
> pad layout, they are to be rectangle with a saw tooth end on one side, 2
> pads. Any help would be appreciated.
> Thanks,
>
> Mary Knouse, C.I.D.
> PCB Designer
> SymCom, Inc.
>
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