Hi all!
With yesterday's discussion on Polyimide stencils and
the associated ESD risk factors (Boy! I gotta admit
that I was a little scared..oops after weeks of
stencil design and evaluation, and assumption that it
is the best we've got, now we end up fighting against
ESD..),  we decided to run a quick ESD test on our
polyimide stencils..and here is what was observed.
- The poly stencil, without doubt, is definitely more
ESD prone than a metal one. Some places on the stencil
was measured holding more than 2000v of charge. But,
an interesting observation was that when the stencil
is put on the printer and after a run or two, when the
charge was measured again, it was very small (around
100v). Something was discharging it and it was not the
PC board. So it was a kinda mixed reaction that was
observed. We dont want to take the risk of going ahead
because, well, sometimes it may happen that the
humidity falls, then these stencils would accumulate
charges, and oops do i have to tell what'll happen!.
We would be printing adhesives using this stencil on
the bottom side, with ICs and lotta ESD sensitive
stuff on the board.
- One of the suggestions were to use an ionic fan
(replace the regular fan on the rear of the printer
with an ionic one), so that we can be safe from ESD
problems, but..i was still kinda worried..and here i
am!

Any bouncing back of ideas/suggestions...???

Regards,
Murugan
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