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Date: | Thu, 2 Nov 2006 17:23:12 -0500 |
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Werner-
How much do we "tip" the gold? 15% or 18%?
Wayne Thayer
>>> [log in to unmask] 11/2/2006 5:06:11 pm >>>
Hi Amol,
I you have imersion Au, Au-embrittlement is not a problem because there
is
not enough Au. Be careful, however, if your PCBs come from China; I
have seen
much thicker Au-layers than are possible with iAu.
Calculating the wt% of Au in a soldert joint is an exercise in
futility,
because you have to make the assumption--frequently not warranted--that
the
SnAu-IMCs are uniformally distributed.
In cases where you suspect thicker Au [and for the matter Ag; which is
equally as bad as Au in causing SJ-embrittlement] deposits, the safest
course of
action is to wash the Au (Ag) off by tipping.
Werner
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