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| From [log in to unmask] Wed Oct 23 16: |
55:34 1996 |
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Steve,
There would only be one potential benefit and that would depend on the
application of your assembly. Ag additions at the 2wt% level do give
improved creep performance. This could be important if your PCB is mounted
vertically with heavy, and hot devices. All the data I've seen so far
indicates that Sn62 has no better fatigue performance than Sn63.
The original intent of 2% Ag additions to solders was to minimize the
dissolution of Ag terminations of chip caps and resistors into the solder
joint by reducing the Ag concentration gradient and thus slowing down the Ag
diffusion rate. Now that most chip device manufactures offer Ni barriers in
their termination metallurgy, Sn62 seems redundant.
Don Foster
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