Les,

An ICT bed of nails test should be able to pick up reversed polarized
capacitors but it will have to apply more than the reverse dielectric
breakdown voltage to do so. It is going to have a much more difficult time
detecting a missing bypass capacitor - all the capacitances in parallel with
tolerances and all is going to make it hard to detect one missing.

I would reconsider AOI - check out Testronics ( http://www.testronics.com
<http://www.testronics.com> ) - they make a low cost (~$50k) machine that
does exactly what you are looking for. I'm trying to justify one for our
operations here. They also do some ICT stuff, but I haven't looked at any of
it in detail. Their AOI is probably going to be cheaper than any used ICT
machine you find anyway.

Blair Hogg
QA Manager
GAI-Tronics Corporation


-----Original Message-----
From: Bogert [mailto:[log in to unmask]]
Sent: Friday, June 28, 2002 6:06 AM
To: [log in to unmask]
Subject: [TN] Seeking PWA Test Information


Hi folks, I am Les Bogert an engineer from Bechtel and am seeking some Test
101 education.  Specifically, are there any PWA test methods out there (e.g.
bed-of-nails, boundry scan, flying probe, etc.) that can be used to: 1)
determine if polarized capacitors are installed in reverse - A method that
will not damage the part from reverse voltage; and 2) method to test if one
bypass capacitor is missing when there are many tied in paralled on the same
PWA.  I know this can be done using automated optical inspection but the
cost is out of the range of what we are willing to spend.  Any help would be
appreciated.  Thanks

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