Hi Kerry
Could you put some epoxy on the tops of the vias?  We have done so on a
design where the designer put a via too close and we had the same issue
- occasional short.  We found it worked fine in our application.

You say no soldermask, and I'd agree that it would not be the best
solution here since it isn't really a good insulator.  What else is
allowed?


regards,

Graham Collins
Process Engineer,
L-3 Communications Electronic Systems Inc.
Halifax
(902) 873-2000 ext 6215
>>> [log in to unmask] 11/10/06 18:33 PM >>>
Hello Esteemed Technet,

Ran into a little issue here.  A board we have has 4 power via's (3.3,
5,
etc) directly under a device that was not supposed to have an grounded
exposed heatsink
on the bottom side.  The nasty result is the occasional short where one
of
the power vias make contact to the heatsink.  I cannot drill out these
vias as there is trace going from these vias directly to the pins of the
device.

I can use kapton tape to cover the vias, but I was looking for a better
solution.
No soldermasking allowed!

Any ideas?
Thanks in advance,
Kerry



Kerry McMullen
Principal New Product Mfg. Engineer
LTX Corporation
825 University Avenue
Norwood, MA 02062-2643
(T) 781-467-5468
(C) 508-631-1832

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