Hi Ioan - take a look at the email archive describe by Steve G. - if the 
surface finish is bright acid tin then you may have an excess codeposited 
plating condition as was described during the Technet conversation on Joe 
Kane's question.

Dave Hillman
Rockwell Collins
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Ioan Tempea <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
04/01/2010 01:37 PM
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Subject
[TN] Grainy after wave






Dear Technos,

 

Please see photo at http://ipc-technet.groupsite.com/gallery/12732

 

The component is a high current fuse holder, see the vertical mini 
-powerclaw, Sn over Ni finish 
http://www.andersonpower.com/products/pcb-powerclaw.html

 

We wave it with SN100C, 525F solder temperature, water soluble flux. As 
you notice, the finish on the left contact turns grainy, compared to the 
one next to it, that keeps the same look as before wave. The copper plane 
connections of the 2 contacts are different, hence a temperature 
differential between the 2.

 

My questions are:

How this happens? Sn starting reacting with the underlying Ni?

Should I worry about this? After all it is only a superficial issue. Can 
it alter the functionality of the contacts (they are supposed to see a lot 
of Amps)?

 

Thanks,

 

Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
T | 450.967.7100 ext.244
E | [log in to unmask] <mailto:[log in to unmask]> 
W | www.digico.cc <http://www.digico.cc/> 

 
 N'imprimer que si nécessaire - Print only if you must

 


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