Ramon,
you have a very good understanding of annealing and it really should remove
the tensions that tend to make whiskers grow.
But, how cost effective it is? Annealing is a very slow process, in
controlled atmosphere. Hence longer turnaround time and more energy needed.
Just an opinion...
Regards,
Ioan
> -----Original Message-----
> From: Dehoyos, Ramon [SMTP:[log in to unmask]]
> Sent: Wednesday, January 28, 2004 8:57 AM
> To: [log in to unmask]
> Subject: Re: [TN] Antw: [TN] Lead-free Component Finishes
>
> 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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