Good morning All.

 

One of our CMs is experiencing either non-wetting and/or dewetting on
the end cap(s) of some 0402 capacitors provided by 2 different
manufacturers. One Cap manufacturer plates using Sn90Pb10 and the other
plates using SN95Pb5. The smt CM is using Kester Hydromark 531 WS,
Sn63Pb37 paste.  The profile is obviously a SnPb type profile.

 

Samples of each caps were sent to an outside lab for a solderability
test and both failed a Dip and Look Solderability test per J-STD-002B -
see attachments. However, both Cap providers informed us that their
samples passed their Dip and Look solderability test.

 

Question --  Subsequent smt runs using the same paste type and profile
but with "pure tin" plated capacitors showed no evidence of either
wetting or de-wetting, which begs the question, what is different about
these Caps that cause the wetting/dewetting issues. Plating?????

 

Look forward to anyone's comments, experience, etc...  People either
think it is capacitor issue or a smt process issue.   thanks

 

-Joe 

 


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