Hi folks! Just one additional comments to the good information that Drew 
provided. Typically, palladium silver finished components have no copper 
or nickel barrier underplating - e.g. the PdAg finish is applied directly 
to the ceramic body of the component (PdAg finishes are very common on 
ceramic bodied component styles). The lack of a metal barrier layer means 
that the PdAg finish can completely dissolve into the solder joint in a 
poorly controlled solder process. If the PdAg finish does completely 
dissolve then you no longer have a metallurgical interface and the overall 
solder joint integrity is poor.

Dave



Drew meyer <[log in to unmask]> 
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11/29/2007 07:28 AM
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Re: [TN] Palladium Silver Surface Finish






Kevin,

We were forced in certain circumstances to use this finish because it was 
the 
only one available on ferrites for a period of time.  There is no big 
problem but 
there is an issue.  Palladium silver finish can wet poorly when it ages. 
Fresh 
parts will likely perform acceptably well.  Older parts may not.  If you 
can do 
so perform solderability testing per IPC/EIA J-STD-002B on each lot you 
receive.  Make sure your supplier knows that part of your accept/reject 
criteria will be based on the results of this test.  If the terminations 
are in 
good condition the parts solder equal to the more common finish.

If the more common finish of nickel barrier with tin coating is available, 
I would 
recommend using that instead of palladium silver.  Based on my experience. 
 
nickel barrier with tin or tin lead has a much longer shelf life and we 
have 
experienced far fewer solderablity issues with this termination.

Drew Meyer 

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