Thank you Dave,
We had a case (my day back with BlackBerry) where a component had literally 10 microns thick pure Ag plating, with absolutely no effect on the strength of the joints :-).
I wish I could have that sample you told about :-).
Sent from my BlackBerry 10 smartphone on the Rogers network.
From: David Hillman
Sent: Tuesday, August 11, 2015 15:46
To: Vladimir Igoshev
Cc: TechNet E-Mail Forum
Subject: Re: [TN] immersion silver
Hi Vlad - due to confidentiality issues, Werner was not able to discuss all of the case but the situation was a castellated component configuration which used silver instead of gold for the castellation finish which resulted in a solder joint that contained a significant amount of silver. The Ag-Sn intermetallics were so bad that the solder joint integrity was compromised. Clearly a silver embrittlement issue but not a case we normally find in the industry.
Dave
On Tue, Aug 11, 2015 at 8:00 AM, <[log in to unmask]> wrote:
Thank you Dave :-). I also had a long discussion with Warner about that case he always referred to but had never seen any specifics. Do you have anything to shear just to feed my curiosity?
Thank you
Vladimir
Sent from my BlackBerry 10 smartphone on the Rogers network.
From: David Hillman
Sent: Tuesday, August 11, 2015 08:28
To: TechNet E-Mail Forum; Vladimir Igoshev
Subject: Re: [TN] immersion silver
Hi team - well, as usual the truth actually lies in the middle of the technical discussion. Supporting Vlad's point, solder is fairly robust to silver in terms of degrading integrity influences so in most of our soldering situations its not an issue. Supporting Werner's point, he did have a specific case where silver embrittlement of the solder joint was the root cause of a series of solder joint failures. Werner and I had long discussions on that case as it was very interesting despite being somewhat of an odd case. So the final answer is silver can be an issue but it takes some specific metallurgical conditions. The immersion silver surface finished used today on printed circuit boards will not contribute to the degradation of solder joint integrity.
Dave
On Tue, Aug 11, 2015 at 7:02 AM, Vladimir Igoshev <[log in to unmask]> wrote:
Hi Guy,
With all due respect to Warner memory, silver IS NOT like gold and DOES NOT cause embrittlement.
Therefore, from the reliability point of view it wouldn't matter what thickness of IAg was on a board, as long as we ONLY talking about the amount of Ag which would and up in the joints after re-flow.
Regards,
Vladimir
Sent from my BlackBerry 10 smartphone on the Rogers network.
Original Message
From: Guy Ramsey
Sent: Tuesday, August 11, 2015 07:37
To: [log in to unmask]
Reply To: [log in to unmask]
Subject: Re: [TN] immersion silver
If Werner were alive he would be reminding us that silver, like gold, is a
contaminate in tin solder.
Early finishes, prior to 2005 or so, weren't good for multiple reflows. Some
presumed it was too thin.
I believe the problem was the durability of the organic additives that
retard oxidation of the silver.
Not perfect, but it is my preferred surface finish, but not too thick.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Kelly
Sent: Monday, August 10, 2015 3:47 PM
To: [log in to unmask]
Subject: [TN] immersion silver
Hi All,
Why would someone choose thick immersion silver over thin? Are these
different chemistries? Regards Steve Kelly
Phone(O) (416) 750-8433
Phone (C) (416) 577-8433
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