Bill,

Have seen it...

Had SJ separation of parts from PCAs under perfectly formed fillets...
On the same PCA had T/Hs de-wetting in barrels and on annular rings...

Agree with Rex on the probable cause (passivated Ni under Au)...

Only recovery action that seems to work is to have the PCAs HASLed with a fairly aggressive flux to clean off the Ni and cover with solder...

Otherwise get new PCAs...

The de-wetting will drop parts that look well-soldered anytime and anywhere...

Paul

Paul Edwards
Surface Art Engineering

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask]
Sent: Tuesday, October 20, 2009 4:21 PM
To: [log in to unmask]
Subject: [TN] ENIG Issue

Fellow TechNetters:  I ran into a problem and I am looking for more information.  We had some PCB made with ENIG for SMT applications.  We populated the backside, ran them through the convection oven, the solder fillets were fine.  Populated the first five (5) PCBs on the topside, ran them through the convection oven, and the solder fillets were quite bad, actually dewetted.  Could not even be touched up.  Tried two (2) more random PCBs and got the same results.  Never have run into this before but have been told it is NOT a unique problem.  Has anybody had this happen?  Have to tell our customer that they are not going to be getting their PCBs on time and would rather not look like the north end of a southbound mule.



Thanks in advance for your assistance.



Bill Black

1 631 667 9699   X13

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