Thanks, Werner.
I see many different profiles being used, for boards but also for specimens
used in mechanical testing (shear or tensile). It looks like different
experiments have different objectives when selecting such or such ageing or annealing
profile.

Now, the things you mentionned about fine vs. standard micro-structure, I
remember that being documented for standard SnPb (as per Roger Wild, for example,
as you mentionned).  Has there been similar investigations and hard data
produced for the new lead-free alloys?  I saw one study, although the conditions
were mild, where 1 hour at 100C did not affect the microstructure or the
strength properties for SnAg.
In the NIST/NEMI test procedures for solder mechanical testing (half-way down
the page at:
Solder Systems in Phase Diagrams & Computational Thermodynamics)

the recommendation is 16 hours annealing at 2/3 of the liquidus (in degree K)
to remove residual stresses in surface-machined cast specimens.  If I use
that for SAC with a melting point at about 217C, I get 16 hours at 54C.

Cheers,
Jean-Paul


_____________________________________
Jean-Paul Clech
EPSI Inc.
Home page URL: http://jpclech.com
P.O. Box 1522
Montclair, NJ 07042
USA
tel: 973-746-3796
fax: 973-655-0815

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