Does the pin wet easily by hand when using a soldering iron?

Why do you think it looks like the pin is floating on top of the solder?
That is just wrong. If all of the other pins wet well, then the part would
have sunk into the solder and the pins would be in contact with the pads on
the board.

So it's a bigger problem than just one pin.

I solve problems like this by using a hot air rework station and pushing the
components around with tweezers to see what happens. Just put a bit of flux
around it and try that. You can quickly gain an intuitive feel for how
"special" this pin, or this part, is. Maybe you just need a bit longer dwell
at liquidus or a bit higher temperature.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jim West
Sent: Tuesday, November 18, 2014 3:13 PM
To: [log in to unmask]
Subject: [TN] Solder defect

Hi all,

Please see attached links. (Thanks Steve)
http://stevezeva.homestead.com/IMG00002.jpg

http://stevezeva.homestead.com/IMG00004.jpg

http://stevezeva.homestead.com/IMG00008.jpg

We have recently come across two failures that were the result of one (1)
pin not soldered on a 144 pin QFP.  Looking at the pictures, you'll see no
wetting and the pin embedded in the solder.  We could say it's
contamination, but we had no issues with any other pins on the QFP.  One
more thing to add to the troubleshooting, the failure is the same pin (36)
on the QFP.  Do I have a warping issue?  The pin doesn't appear to be bent,
but I have not ruled that out until I have better means of verifying.  If
it's contamination, why only one pin?  I would think that I would get at
lease the heel or toe, or even the sides to solder, but in this case no
wetting.  You can see the pin has made contact with the solder due to the
indentation.  How does this not solder if it has made contact with the
solder paste?  I'm at a loss and we will probably end up sending this to a
lab, but I'm not sure if we will gain anything from a lab??

We are using leaded solder for this application.
Photo IMG00002 and 00004 are from the same failure Photo IMG00008 is the 2nd
failure.

Your thoughts?

Thanks,
Jim


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