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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]>
Sent by: TechNet <[log in to unmask]>
11/29/2007 07:28 AM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Drew meyer <[log in to unmask]>
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Subject
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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Technet Mail List provided as a service by IPC using LISTSERV 15.0
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