Hi Kevin! There are a number of metallurgical and microstructural reactions
that can result in a solder joint not having a "bright and shiny"
appearance. The majority of the time the lack of a "bright and shiny"
appearance results in absolutely no change in solder joint integrity. The
other minority instances, such as too much gold in a solder joint resulting
in a grainy appearance, the solder joint integrity is impacted. If you had
"bright and shiny" solder joint appearance before then something has
changed in your process - the change may not impact the solder joint
integrity but you should trace down what is now different. The use of
Pbfree solder alloys is going to make the "bright and shiny" solder joint
appearance follow the dinosaurs into extinction! JSTD-001 committee removed
the "bright and shiny" appearance criteria several years ago. The
IPC-HDBK-001 has some good information on "bright and shiny" that may be of
use.

Dave Hillman
Rockwell Collins
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             Kevin Glidden
             <[log in to unmask]
             COM>                                                       To
             Sent by: TechNet          [log in to unmask]
             <[log in to unmask]>                                          cc

                                                                   Subject
             11/08/2005 11:59          [TN] Grainy Solder Joints
             AM


             Please respond to
             [log in to unmask]
                    om






We are experiencing dull / grainy TH solder joints, made by hand soldering
w/ iron @ 500F.  At first, it appeared to be residue on the surface, so I
started chasing the cleaner.  But all checked out OK.  I refluxed (water
soluble, ORH0) and reflowed (iron @ 600F).  This improved the finished
appearance, but not 100%.  While eutectic, the joint is perfect.  Then when
I draw the iron away, it cools and the surface finish is no longer smooth
or
shiny.  What can cause this?


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