Hi Joe - I recommend that you request the following information from the 
component fabricator:
- which JSTD-002 test method did they use
- who is the solderability flux suppler and what is the product number of 
the flux they used for testing
- what solderpot  temperature did they use for the solderability test

It is not uncommon to find that an incorrect solderability test flux is 
being used by the component fabricator. And as a possible root cause for 
the solderability issues you have encountered - high tin percentage 
component surface finishes are more prone to oxidation issues than the 
lower tin percentage alloys.

The JSTD-002 specification is currently in ballot and will contain a 
complete set of leadfree solderability test parameters when issued.

Good Luck.

Dave Hillman
Rockwell Collins
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Subject
[TN] Question - solderability issues with Sn90Pb10 plated 0402 caps






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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