Any comment on Steve's stratification theory?  A few years back I had SPC
charts at a HASL pot at a PC fab, with analysis every two weeks.  Cu
content stayed 0.21% to 0.24% over a period of 1+ years, even though all we
were doing was skimming stuff off the top.  Lou Hart

-----Original Message-----
From:   Stephen R. Gregory [SMTP:[log in to unmask]]
Sent:   Tuesday, August 14, 2001 10:04 PM
To:     [log in to unmask]
Subject:        Re: [TN] Solder analysis results

Dave,

Surely, not ALL 1700-lbs.? Wooo-doggies! I can only imagine what a task
that
would be!!! I've read some stuff that if you keep the pot static, and keep
it
at a stable temperature for a period (what this really is, I don't
know...there's varying opinions), the metals will seek their own level
(according to the different opinions, the copper will be towards the top),
then you scoop out out the top layer, and replenish what you've removed
with
fresh bars.

The question that I have though, how did the pot get so out of balance with
copper? I've never had a problem with copper content, even when waving OSP
boards...tin levels dropping, yes. But not excessive copper...somebody
throw
some pennies in the pot?

-Steve Gregory-


> RJ Klien Wassink suggests [bible p 169] pouring contaminated solder at
about
> 190°C through a 20 mesh stainless steel stariner to reduce copper content
to
> 0.25%.
>
> Dave Fish
>


 << File: ATT00002.htm >>

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