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June 2009

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From:
"David D. Hillman" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 23 Jun 2009 07:22:13 -0500
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Hi Steve - ah, the beauty of being a materials engineer is that the 
industry doesn't seem to learn from past material mistakes so I really 
don't need to learn anything new! I recommend you check with your 
connector vendor to confirm that the connector surface plating is bright 
acid tin. The photos appear to show a bright acid tin surface finish that 
has blistered during the solder reflow process due to excessive 
co-deposited organic material. Bright acid tin finishes (plated correctly) 
look very nice but have terrible solderability characteristics and are a 
known tin whisker generation source.  It appears that you may have had a 
surface plating change from what you normally had been procuring. Good 
luck.

Dave Hillman
Rockwell Collins
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Steve Gregory <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
06/23/2009 06:49 AM
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TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Steve Gregory <[log in to unmask]>


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Subject
[TN] "Blumpie" looking connector leads...






 Morning all!
 
Trying to stay cool here! Broke 100 degrees yesterday and Sunday, and
it's probably going to break 100 degrees today. Summer has come with a
vengeance! 
 
Ran across something yesterday that I've never seen before. We build a
board that uses this AMP Densipac SMT connector:
 
http://tinyurl.com/nqbpcp
 
 
We've built a lot of these boards before without any issues at all. This
latest run we have something going on with these particular connectors.
Here's a photo of them on the PCB:
 
http://stevezeva.homestead.com/files/AMP_Connectors.jpg
 
You can probably see that the leads have this "Blumpie" look to
them...both bumpy and lumpy. This is fresh out of the reflow oven.
Here's a closer look:
 
http://stevezeva.homestead.com/files/Connector_Blumpies.jpg
 
If you notice the two pins either side of the white line look fine. They
are the anchor pins that are for mechanical strength for the
connector...they are not I/O pins. The rest of the board looks
absolutely fine too. Not a bit of problem. It's just the I/O pins. We
have noticed that connectors with certain date codes don't have this
problem. Also, before reflow the connectors look okay. Luckily we've
only built a few boards, and we're stopping until we can get to the
bottom of this...
 
Have any of you ever seen "blumpie" connectors like these before?
 
Steve

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