Keith

Thanks for this comprehensive and interesting information. I'm coming
back to you on the lower dross formation. Do you ascribe the lower
weight to less metal in the mix (as you mention), the lower density of
the alloy or that a smaller number of atoms, at the wave surface, are
actually oxidising (or a combination)? Also, have you analysed the dross
to find out whether > eutectic proportions of copper are oxidising? If
this were the case, then it may be that the copper content would tend to
auto-stabilisation, promoting longer pot lifes.

Coming back to your earlier post, you mentioned using a flux with a
relatively high solids content by modern standards. In this post, and
others, you mention double-wave machines with higher preheat. Surely,
with this combination, the use of low-solids or even medium solids (~5 -
~8%) would be almost out of the question as there would be precious
little flux left to aid the peelback on exiting the smooth wave. Would
you agree?

Long time no hear from you!

Best regards,

Brian

> Vadali Mahadev wrote:
>
> Hello,
>
> I agree with all the people voting against splitting the group.  The
> reasons for switching to lead free is just important a discussion
> topic as the technical details.  In most instances they are dependent
> on each other.
>
> Also, I am looking for information on changes that are necessary in
> designing the boards to accommodate the lead free packages.  Are there
> any guidelines/information on what works good for the Sn-Ag-Cu and
> Matte Sn based solders?  for BGAs? for QFPs?
>
> Thanks
> Vadali Mahadev
>
> PS:  As always all information presented here are only mine and in no
> way connected to my employer.

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