I've seen this first hand.  Parts that were marginal (but acceptable) in
a SnPb reflow process were unacceptable in a Pb free reflow.
Cross-sections showed that the termination had pretty much disappeared
into solution in the solder joint and the solder was dewetting from the
ceramic body of the component.


Scott Post
P.O.U. 1415-00M2-00P6
2151 E. Lincoln Road
Kokomo, Indiana    46904-9005
765-451-2983 (Phone)
765-451-0287 (FAX)

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Glidden, Kevin
Sent: Monday, July 20, 2009 3:30 PM
To: [log in to unmask]
Subject: Re: [TN] Leadfree compatibility of Silver Palladium
terminations?

Peter,

One of the many items I've learned through Technet and am happy to pass
on...

Palladium silver finished components have no copper or nickel barrier
betweem the component substrate and the finish plating, and thus the
finish plating will leach into the solder joint and leave no
intermettallic between the solder joint and the component body,
resulting in poor solder joint reliability.  This is exacerbated by the
higher Pb-free reflow temperatures.

Kevin Glidden

-----Original Message-----
From: Peter L [mailto:[log in to unmask]]
Sent: Monday, July 20, 2009 1:36 PM
To: [log in to unmask]
Subject: [TN] Leadfree compatibility of Silver Palladium terminations?

Hi,

I am wondering if anyone has experienced issues with leadfree reflow
soldering small discrete chips (0805) with silver palladium
terminations? According to one particular manufacturer (EPCOS) they do
not approve it and claim that the termination will be "damaged" under
leadfree processing temperature. I am curious to know the reason behind.
Thanks.


http://www.epcos.com/web/generator/Web/Sections/ProductCatalog/Protectio
nDevices/CeramicTransientVoltageSuppressors/PDF/CTVS__Soldering,property
=
Data__en.pdf;/CTVS_Soldering.pdf

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