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May 2007

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Subject:
From:
"Wenger, George M." <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wenger, George M.
Date:
Fri, 25 May 2007 14:50:00 -0400
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Were the issues with silver plated component issues back i
Dave,



Were the issues with silver plated component issues back in the SMART

conference era diagnosed as solder joint embrittlement by silver because

of too thick a plating or were they termination failures on the silver

plated components.  In the RF world silver plating is liked by the

design community because of its electrical properties.  However, solder

assembly engineers always have difficulty trying to make reliable solder

joints to components that have upwards of 15 to 20 microns of silver

plating.  When you look at the dissolution rate of silver into solder

you realize very quickly that when you try to solder to silver plating

this thick you wind up making a solder joint to the plating and not to

the base metal.  So the question really is that when a solder joint made

to thick silver fails why did it fail?  Was it due to silver

embrittlement or was it because you made a solder joint to silver rather

than a base metal.  If all of the silver isn't dissolved then if you

evaluate the silver content across the termination interface you see

that the silver content in the solder may be a couple of percent but

when you reach the silver plating side of the termination the silver

content is at 100%.  One needs to make sure that an analysis of the

failure mode is done in order to classify solder joint failures.  I for

one do not believe that silver embrittlement is worst than gold

embrittlement.  Certainly I've seen many more solder interconnection

failures on joints made to thick silver plating than I have to ENIG or

even thick 1 micron of gold plating but I've never seen any data

anywhere that shows solder joints made to silver those thickness is 0.05

to 1 micron is any more brittle that solder joints made to 0.05 to 1

micron of gold. 



Regards,

George

George M. Wenger

Andrew Corporation Wireless Network Solutions

Senior Principal FMA / Reliability Engineer

40 Technology Drive, Warren, NJ 07059

(908) 546-4531 [Office]  (732) 309-8964 [Cell]

-----Original Message-----

From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman

Sent: Friday, May 25, 2007 12:51 PM

To: [log in to unmask]

Subject: Re: [TN] Silver Embrittlement?



Hi folks! Just a comment. Some of Werner's comments of Ag embrittlement 

are based on some ceramic components with silver plated finishes which 

resulted in severe solder joint issues on a series of investigations

back 

in the SMART conference era. The IPC-4553 Immersion Ag finish group is

in 

the final stages of finishing up an investigation where Immersion Ag 

surface finish was applied to test vehicles in both 1X and 3X

thicknesses 

plus combine with SnPb and Pbfree soldering processes. The goal of the 

testing is to characterizes and determine if silver embrittlement of 

solder joint can be created under practical applications. The thermal 

cycle testing is complete and 100+ cross sections are undergoing SEM 

elemental mapping analysis. The report will be completed this year -

keep 

an eye on the IPC-4553 group activities.



Dave Hillman

Rockwell Collins

[log in to unmask]









Werner Engelmaier <[log in to unmask]> 

Sent by: TechNet <[log in to unmask]>

05/25/2007 08:12 AM

Please respond to

TechNet E-Mail Forum <[log in to unmask]>; Please respond to

[log in to unmask]





To

[log in to unmask]

cc



Subject

Re: [TN] Silver Embrittlement?













Hi Lee,

Au- and Ag-embrittlements are certainly documented?the combined effect

is 

simply my extension of the phenomena.



Werner







**************************************

 See what's free at http://www.aol.com.



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