My experience is the same. Yes, it can be done. But, not by accident.

If your processes are set in the middle of the process window for nickel
plated or tin plated caps, you will sort out the AgPd parts. They will be
the parts that look like cold solder. 

But, increasing heat and flux and attaching them is a solder pencil is
exactly the wrong thing to do. 

This type finish is not exclusive to capacitors. I have seen resistors and
inductors too. 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar
Sent: Thursday, July 03, 2008 8:23 AM
To: [log in to unmask]
Subject: Re: [TN] Antw: [TN] Silver-Palladium termination SMT solder
problems

It depends of course on the solder temperature, solder exposure time and the
AgPd thickness. We have soldered to AgPd pads, and the solder exposure time
was set to a few seconds. The AgPd was as thick as some
25 micrometers. Thickfilm fellas talk about 'leaching'.

Inge 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guenter Grossmann
Sent: den 3 juli 2008 14:00
To: [log in to unmask]
Subject: [TN] Antw: [TN] Silver-Palladium termination SMT solder problems

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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