Steve,
A couple of questions before I give you my answer.  What is the flux in the solder paste you are using and when you touch up the non-wetted pads what is the iron temperature and what is the flux in the cored solder wire you are using?.  Also, are the discrete components you showed with non-wetting occurring on the bottom side first pass reflow or on the top side second pass reflow? 

Regards,
George
George M. Wenger
Failure Signature & Characterization Lab LLC
609 Cokesbury Road, High Bridge, NJ 08829
(908) 638-8771 Home (732) 309-8964 Mobile
E-mail: [log in to unmask]
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, May 07, 2013 11:48 AM
To: [log in to unmask]
Subject: [TN] Irritating ENIG Non-wetting

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

 


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________