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July 2008

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Subject:
From:
Hernefjord Ingemar <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Hernefjord Ingemar <[log in to unmask]>
Date:
Thu, 3 Jul 2008 14:23:25 +0200
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text/plain (104 lines)
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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