Brian,
 
I seem to remember hearing somewhere that lead-free solder joints, especially
ones that are fairly large solder joints, may show a higher amount of cracks
in the surface than SnPb joints of the same size. (I think the reasons had to
do with amount of thermal expansion and contraction, and cooling rates??)
 
I don't know if those types of surface cracks would be the same or look the
same as solder stress lines, but that could be part of the explanation.
 
I also know that many of the lead-free solders have a duller appearance than
SnPb solder and that has been an issue for QA people who are switching from
SnPb solder and are used to seeing smooth, bright and shiny solder joints. 
 
-Camille Good
Portland, Oregon
 
P.S. You may want to contact someone on the IPC committee that wrote
IPC-A-610D. They should have more information.

Brian O'Connell <oconne...@tamuracorp.com> wrote:

Good People,

I am performing a quality review on an unit based on IPC-A-610D.

Section 5.2.7 indicates that solder stress lines are acceptable for
lead-free solders, but not for leaded solders.

Does this make sense to anyone ? What great revelation am I missing ?

Thanks and luck,
Brian

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