1.    White oxide forms a 100-1000 Angstrom copper/tin intermetallic during
pressing or upon aging.  Dendritic growth (whiskering) from such a thin
copper/tin intermetallic is impossible and has never been observed.

2.    There are now a bunch of us supporting the DuraBOND 'white oxide'.  And,
one of us, John Nash I believe, suggested we market a black version.  It was
reduced to practice and a patent applied but we have not gone to the field.
Internally we have debated if color is that important an issue.  Millions of ssf
of our white 'white oxide' end up in MLB's every month.  And, we've been a bit
obsessed with ultra thin packages, new prepregs and thermoplastics, and DfE
(Design for the Environment).

Would a conveyorized black 'white oxide' oxide alternative be useful to the
industry?  

Sincerely,

Craig Bishop





You wrote:
> I've been following this oxide alternative thread with some interest,
> and can add the following comments.
> A number of our board suppliers have either implemented these
> alternatives, or are considering it & seek our approval. We can't accept
> the light color of the Durabond or other tin process  for our
> applications, which effectively rules them out (for us anyway.) Another
> list subscriber mentioned dendritic growth, we didn't get that far but
> it could be a valid concern. As far as the peroxy-sulfuric type
> alternatives go there only seem to be 2 players right now, Alpha &
> MacDermid, with very similar looking products. Performance is similar,
> with the peel strength #'s being slightly higher on the Alpha Prep
> samples. As a general comment we find time to delamination is improved
> with these oxide alternatives. Alpha claims to have a greater installed
> base of customers, whch makes us as an end user feel slightly more
> comfortable when accepting product built with new technology.
> 
> Dr. Thomas Peters
> 
> 
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