Hi,

 The surface of the solder where things did wet looks rather uneven. Do you
have:

 1 Reflow profile info.

2 Flux type

 3 A close up of the soldered balls.

 I agree it looks like non-wetting but there might be something else going
on. Even with SAC305 I would expect a better finish through it is hard to
see given that picture.

Bob K.




-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Karen Tellefsen
Sent: Thursday, March 13, 2014 10:21 AM
To: [log in to unmask]
Subject: Re: [TN] BGA non wetting pads

Two papers from Intel

Fundamentals Of The Non-Wet Open BGA Solder Joint Defect Formation
http://www.smta.org/knowledge/proceedings_abstract.cfm?PROC_ID=3447

The Challenges Of Non Wet Open BGA Solder Defect
http://www.smta.org/knowledge/proceedings_abstract.cfm?PROC_ID=3547

Karen Tellefsen - Electrical Testing
Alpha / 109 Corporate Blvd./ S. Plainfield, NJ 07080 [log in to unmask]
908-791-3069



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