Alas I have given up my timing light and dwell meter!  I no longer directly
support a wave solder operation, but I direct the laboratory which determines
their tin and contaminant levels.  The Military Avionics group runs virtually
no solder paste across the wave, they solder exclusively older technology PTH
hardware.  Our commercial avionics group has recently switched to a nitrogen
air blanket plus has a PO for testing with their solder supplier so I am not
aware of their experiences.  The 3 years of data I have in my computer suggests
that a large portion of the gold goes out with the dross because it has never
been a problem, nor has copper.  Gordo
_______________________________________________________________________________
Gordy, you said:

>Also keep in mind that some of the gold is dragged out with the dross that is
>removed on a daily basis when using a "dry" wave solder pot.  I have
experience
>with oil covered wave solder pots and they do indeed exhibit a build up of
>gold, primariy because you are not forming dross and hence not removing some
>contaminants.  We typically dumped an oil covered pot every 3 months either
due
>to gold or copper contamination levels.  When we changed wave solder machines
>to a "dry" wave we found we could go years without dumping the solder pot even
>though what we soldered had not changed.
>
>Gordy Seppanen, Process Engineer
>Military Avionics
>Honeywell Inc.

Yes, I'm sure you are right. I used to have an old Dee Electric machine
with an oil blanket, and an old Hollis oil intermix (yeccch). Those pots
built up copper a lot faster. The dross formation definitely carries out
some metals in the form of oxides. Good point. Whether gold specifically
would stay in solution with the tin, I dunno.

However, these days I'm putting fewer bars in the Electrovert every month,
and I'm using more paste - how about you? Seems like all that experience of
wavesolder maintenance and operation is like knowing what to do with a
dwell tach and timing light...

cheers,

Jerry Cupples