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Subject:
Antw: [TN] Silver-Palladium termination SMT solder problems
From:
Guenter Grossmann <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guenter Grossmann <[log in to unmask]>
Date:
Thu, 3 Jul 2008 14:00:09 +0200
Content-Type:
text/plain
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text/plain (67 lines) 
Grant

You have the same effect when soldering with tin lead. AgPd terminations are not intended to be soldered. The surface is optimised to be fixed with adhesive. AgPb solves very easy in tin alloys. The effect is that the entire metallisation is solved in the solder. The alloy that forms looks as if you had a bad wetted solder joint. If you have a ,microsection done you will see that the AgPd metallisation has mostly gone into the solder, in extreme cases exposing the ceramic of the capacitor.

Best regards

Guenter




_____________________________________________________

EMPA
Swiss Federal Laboratories  for Materials Testing and Research
Centre for Reliability
Guenter Grossmann,  Senior Engineer

8600 Duebendorf
Switzerland

Phone: xx41 44 823 4279
Fax :     xx41 44 823 4054
mail:     [log in to unmask]
_____________________________________________________

>>> Grant Emandien <[log in to unmask]> 07/02/08 11:19 am >>>
Hi all,
 
We are experiencing poor solderability with AgPd-terminations on MOVs
exposed to a lead-free reflow profile using a SAC alloy on an
ENIG-finished PCB. Though we have run this board only once previously
with the same part finish using a lead-rich alloy, we had similar
effects but not to the extent we are now experiencing.
 
Can anyone provide some insight into this/
 
Regards
Grant
 

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