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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, David Hillman <[log in to unmask]>
Date:
Thu, 17 Sep 2015 07:44:54 -0500
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Hi Jeff - just some additional info for the discussion. Pd and Au act
somewhat similarly in solder situations except for two big characteristics:
(1) the dissolution rate of Pd in solder is orders of magnitude slower than
Au; (2) the amount of Pd to cause solder joint embrittlement is lower than
for Au (1% vs 3%). The good news is that the re-segregation of Au to solder
joint interfaces that occurs in ENIG doesn't happen with Pd. The IMC phase
that is the  trouble maker is PdSn4 and it can result in solder joint
failure under some conditions. Gold embrittlement is much more of an issue
(the IMC phase is AuSn4) for the industry. Mike Wolverton, Raytheon,
published a very good paper in the 2011 SMTAI Conference proceedings
(session SUB3) that covers the topic well. The IPC-4556 specification on
ENEPIG contains a weath of data in its Appendices. And one last comment,
there is some misinformation running around the industry that ENEPIG is not
compatible with tin/lead soldering process which is incorrect. Hope this
helps.

Dave Hillman
Rockwell Collins
[log in to unmask]


On Wed, Sep 16, 2015 at 11:01 AM, Jenkins, Jeffrey A @ CSG - LINKABIT <
[log in to unmask]> wrote:

> Hi All,
>
> Quick question, with an ENIG finish, I know the gold dissolves into the
> joint and we solder to the Ni.
>
> But what about ENEPIG?  I'm assuming the Au will dissolve, but what happen
> with the Pd? Does it stay put or also dissolve into the joint?
>
> Inquiring minds want to know.
>
> Thanks,
>
> -Jeffrey
>
> Jeffrey A. Jenkins
> Sr. PCB Staff Designer, CID+/CIT
> L-3 Communications, Linkabit Division
> Work:  858-552-9832
> Email:  [log in to unmask]
>
>
>
> ______________________________________________________________________
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