Thanks Dale

From the other responses I've gotten and yours,,,No-clean unlikely the
issue.. Several have mentioned the spacing.

Most of the failures have not actually been the caps but the driver
transformer connected to them. Our test eng thinks that possibly the leakage
is increasing the load current (not enough to burn the part) and overloading
the transformer (which burns up and causes a cascade fail of the input
transistors connected to the primary). The backlights them selves are 6mA
typical draw and the circuit is rated for 6mA.



_____________________________
Andre Leclair
Process Engineer
Ansen Corporation
315-393-3325 ext 293
315-393-7638 FAX


-----Original Message-----
From: Dale Ritzen [mailto:[log in to unmask]]
Sent: Wednesday, April 05, 2006 2:39 PM
To: 'TechNet E-Mail Forum'; 'Andre Leclair'
Subject: RE: [TN] Arching or Current Leakage


Hello Andre,
Over time we have found the no-clean process we use to be electrically
inert. It neither promotes nor retards arcing or current leakage across the
top of an assembly. I don't know what no-clean products you specifically
use, but as a rule I would say that if you are using a no-clean
solder/flux/paste, you should be safe in saying that it's not a root cause
of the failure the customer is seeing. I would look at component spacing and
possibly isolating the leads from each other if dead or burned caps are the
symptom of the failure.

One long shot (very long shot) is that there might be a repeated under-etch
(near short) condition on the PCB traces leading to this circuitry. I have
seen this in one incident only, but it was finally found by following traces
back away from the components in question. And it was consistent from board
to board. Again, very long shot...

Dale Ritzen
Quality Manager
Austin Manufacturing Services

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Andre Leclair
Sent: Wednesday, April 05, 2006 1:12 PM
To: [log in to unmask]
Subject: [TN] Arching or Current Leakage


We have a customer that has a portion of a circuit which randomly fails.
The circuit is a backlight driver (500volt 6mA). The output caps are 0.100
spacing of the terminals.  The process used is No-clean.  Can the No-clean
contribute to failures of the circuit (ie promote arching or current
leakage across the body of the output caps). ???

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