Hi TechNet - the gold plating of an ENIG surface finish is primarily 
protecting the underlying nickel from oxidation so that an active flux is 
not required to produce a solder joint. During soldering the gold diffuses 
into the solder allowing a tin/nickel intermetallic phase to form creating 
the basis for a metallurgical joint. If the nickel gets oxidized, then a 
highly active flux is typically needed to allow the same reaction to 
occur.

Dave Hillman
Rockwell Collins
[log in to unmask]



From:   Robert Kondner <[log in to unmask]>
To:     <[log in to unmask]>
Date:   08/29/2013 03:03 PM
Subject:        Re: [TN] Solder joint failure
Sent by:        TechNet <[log in to unmask]>



I agree. The flux makes a big difference.

 I regularly solder to nickel tabs that are spot welded to battery cells. 
I
played with various flux materials, the thick RMA flux from flux pens has
worked best. I have also solder coated by dipping in a solder pot, that 
RMA
works well.

 This always concerned me about ENIG, once the gold is dissolved off the
surface what happens next? 

 Bob K.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Glidden, Kevin
Sent: Thursday, August 29, 2013 3:01 PM
To: [log in to unmask]
Subject: Re: [TN] Solder joint failure

In my experience nickel is NOT easy to solder to at all.


-----Original Message-----
From: Victor Hernandez [mailto:[log in to unmask]]
Sent: Thursday, August 29, 2013 2:53 PM
To: [log in to unmask]
Subject: [TN] Solder joint failure

Fellow TechNetters:

   Should I be concern with an electroless matted nickel plating over an
aluminum sheet metal surface and solder onto a copper heat tube?   I 
recall
something about directly soldering onto a nickel surface.  Beside nickel
oxidation.    Any suggestions would be greatly appreciated.

Victor,

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