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Date: | Mon, 11 Nov 2013 11:39:30 -0500 |
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While reading some papers on SnBi solder and SAC solder interaction, I
stumbled onto this set of statements in a 2010 paper Copyright ACI, The
Lead Free Electronics Manhattan Project - Phase II.
Intermetallic Fracture
. With Cu supplied by the solder, attaching to Ni pads can be problematic
. (Cu1-xNix)6Sn5 intermetallic IMC forms over a layer of Ni3Sn4 at the Ni
pad
. The Ni atoms are substituted on the Cu lattice
. Weak boundary between intermetallics
. Mechanical shock and handling risk
The statements were associated with a image "SnNi and SnNiCu intermetallic
compounds found when using SnAgCu solders," IPC/Soldertech Global 2nd
International Conference on Lead Free Electronics.
We don't do much Pb-free soldering. But all of our boards, or nearly all,
are gold over nickel. Is this a real concern? Wouldn't this kill ENIG as a
SAC compatible finish?
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