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May 2013

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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, 7 May 2013 11:05:08 -0500
Content-Type:
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Hi Steve - giving the fact that you can touch up the pads and form a good 
solder joint, you don't have a solderability issue. However, you do have a 
soldering - ability issue. Look at your two capacitor instances, you have 
a very large pad for one termination and a much smaller pad on the other 
termination with the solder paste deposit balling up on the capacitor 
termination on the large pad side. The capacitor termination is getting to 
183C before the pad and thieving all of the solder to itself. I recommend 
checking your reflow profile - good chance you need to slow down the 
conveyor speed or increase the oven temps slightly such that both the 
terminations and the pads both get to temperature equally (or within 
reason) . Your connector example could be in the same bucket depending on 
how many layers of copper it is hooked into.

Dave Hillman
Rockwell Collins
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From:   Steve Gregory <[log in to unmask]>
To:     <[log in to unmask]>
Date:   05/07/2013 10:49 AM
Subject:        [TN] Irritating ENIG Non-wetting
Sent by:        TechNet <[log in to unmask]>



Hi All,

 

We just were running some boards (ENIG finished) where we're seeing this
sporadic non-wetting on some of the pads:

 

http://stevezeva.homestead.com/PKG2.jpg

 

http://stevezeva.homestead.com/PKG3.jpg

 

http://stevezeva.homestead.com/PKG4.jpg

 

Usually it's just a few pads and the rest of the board is fine. We get
the boards in packs of 20, and it's only a couple or so out of the pack
that exhibit the problem. It's just enough to be irritating.

 

When we touch the locations up with a soldering iron they wet fine.
We're using a 63/37 water soluble paste, and the problem doesn't confine
itself to just certain pads or parts, it's random.

 

Like I said it's just enough to be irritating.....   /:o[

 

Steve Gregory

 


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