Hi John! A white deposit on a matte tin finish can not be a good thing and
is not normal for the matte tin finishes I am familiar with. I would
subject the components to the JSTD-002B Test S (Surface Mount Simulation
test) to see if it passes. If it fails then you have leverage with your
vendor based on data and not observation. Good Luck.

Dave Hillman
Rockwell Collins
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             John Burris
             <johnhburris@GMAI
             L.COM>                                                     To
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                                                                   Subject
             01/19/2006 08:54          [TN] Soldering matte tin over
             AM                        nickel plating


             Please respond to
              TechNet E-Mail
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             ; Please respond
                    to
                John Burris
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                  L.COM>






Dear TechNetters,

We are just starting our journey into lead-free (we are currently covered
under Article 9, but we can see the handwriting on the wall), and we are
starting to deal with some issues as suppliers are making component changes
to comply with RoHS. The component at issue is a heat sink for a TO-220
transistor. Flux is 2% no-clean. Solderability is not good; partial solder
adhesion (about 20-30%) on the mounting tabs. 90% coverage is required by
standards.  The matte tin finish appears to have a white deposit that can
be
removed by either scraping or cleaning with a mild solvent. Vendor says
this
is normal and should not affect solderability.

Thoughts?

John Burris

Automated Logic

1150 Roberts Blvd.

Kennesaw, GA 30144-3618

01.770.795.4827 (Office)

01.770.795.3527 (Facimile)

01.404.431.9109 (Cellular)




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