Hi gang! One additional consideration to keep in the radar scope is that
the annealing process and the solderability of a component finish don't get
along too well. You may eliminate/reduce the risk of tin whiskers but the
solderability may be damaged to a point of nonuse.

Dave Hillman
Rockwell Collins
[log in to unmask]




                      "Dehoyos, Ramon"
                      <ramon.dehoyos@NG        To:       [log in to unmask]
                      C.COM>                   cc:
                      Sent by: TechNet         Subject:  Re: [TN] Antw: [TN] Lead-free Component Finishes
                      <[log in to unmask]>


                      01/28/2004 07:57
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to
                      "Dehoyos, Ramon"






                 Annealing the plating can reduce the internal stress in
the
        plating and diminish whisker growth.
        Wrong?



        The annealing process could be the answer to the whisker problem.
Normally molecules of materials are in clumps and their north south pole
orientations of each    clump are pointing in every direction.  Their
molecule clump structure is very fragile which allows them to grow.. When a
material is annealed the molecules poles        of the whole, point in the
same direction. The molecules of the material are  attached to each other
form every side, thus a strong material.. The attachment will   prevent
them
from creating growths or whiskers. I am not a material expert, but have
annealed materials for a long time and know a little about the theory
behind it.. Perhaps some of the materials experts can correct my simple way
of explaining annealing and/or add from their expertise..
        Regards,
        Ramon

> -----Original Message-----
> From: Guenter Grossmann [SMTP:[log in to unmask]]
> Sent: Monday, January 26, 2004 11:39 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Antw: [TN] Lead-free Component Finishes
>
> Jim
>
> I was talking last week with a person from Motorola Germany and a
> someone from Collini. In the discussion both told me that by using a Ni-
> underplate and with the appropriate plating chemistry they don't' see
> problems with whiskers anymore. Earlier, in a conference from
> Electrosuisse, I had a discussion with a speaker talking about whisker
> growth as a function of grain size of the Sn plating which can be
> controlled with the appropriate chemistry and process parameters. What I
> learned in these discussion was that whiskers are a problem that can be
> controlled. In the worst case, in my understanding, it's a question of
> money. Annealing the plating can reduce the internal stress in the
> plating and diminish whisker growth.
> Wrong?
>
> Best regards
>
> Guenter
>
>
>
> EMPA
> Swiss Federal Laboratories  for Materials Testing and Research
> Centre for Reliability
> Guenter Grossmann,  Senior Engineer
>
> 8600 Duebendorf
> Switzerland
>
> Phone: xx41 1 823 4279
> Fax :     xx41 1 823 4054
> mail:     [log in to unmask]
>
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