I have not ever seen that as a failure mode myself but I would wonder if you
have stressed the caps at all on the solder side thermally or either side
mechanically. Have you been able to replicate the mode of failure by running
controlled testing? 

Kat

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Tuesday, July 01, 2008 5:26 PM
To: [log in to unmask]
Subject: [TN] Electrical Test Failures

Fellow TechNetters I Really Need Some Help:

I'm having a problem with a mixed technology PCB failing E/T for low voltage
leaking.? The SMT components are mostly R's and C's with various I/C's.? The
Thru-Hole components, besides various connectors, are IRF4905, Thru-Hole.?
The SMT solder paste is aqueous and our process calls for three separate
washes.? The PCB solder resist is LPI with a dull, matte finish.? Has anyone
with aqueous experience ever had a problem with paste/washings leaving any
type of residue which can cause a leakage problem?

I thank all you folks in advance for your assistance.

Bill Black
Medco
Tel?? 1 631 667 9699.?

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