In a message dated 1/19/99 2:07:29 PM Pacific Standard Time,
[log in to unmask] writes:
<< I will like to know is there is a way to calculate the amount of solder
bars that I will spent for example during a month. I am asking regarding
any calculation or formula and try to avoid buying them by guessing. I will
like to consider the amount of solder that will be used in all leads ( I
will totalize the leads) and due to metallurgical reaction the amount of
solder that will oxidize, and will transform to dross.
Thanks,
Ruben E. Irizarry-Guzman
I/O Product Engineer >>
Hi Rubin!
What I would do Rubin, is instead of trying to rack your brain figuring
out some math formula to predict how much solder you're going to use over a
month, is just set yourself up a MIN/MAX type of deal.
Say you'll start with a full pot and you make up a solder stash of 500
lbs a month. When your stash level gets down to 100 lbs., that's the trigger
to order more. After tracking things a while and building up a history, you'll
know how much you go through. Besides, you're supposed to track the solder you
use anyway, at least here in Sunnyvale I do, and I imagine over in Fremont
you'll need to also. You know, hazardous waste and all that...
About the only way to absolutely know for sure how much solder you use in
a month is to track and record it, along with weighing how much dross you pull
outta the pot. You should also keep a listing of the products you ran, and the
soldering parameters you used for each product to fully get a feel of how much
solder you're really going through. Trying to predict how much you'll use is
tough because there's so many variables that will affect how much you go
through. You can probably give a fair estimate, but is that really going to be
meaningful?
As you probably know, there are things one can do to reduce the amount of
dross generated (besides inerting your machines atmosphere, or keeping the
pumps off...GRIN) The higher the pot temperature, the more dross you make. The
more the solder is agitated (for instance using a chip wave), the more dross
you make. If you don't pre-heat the boards enough to dry the flux enough
before it hits the wave, the more dross you make. If you scrape the pot and
wave formers exessively with wire brushes and scrapers when cleaning the pot
you'll introduce iron into the pot, which causes?...You got it, more dross.
I use Kleenox, but only when I'm gonna clean the pot. I'll gather all the
dross up on one side of the pot, and then sprinkle the kleenox over the pile
and work it in a bit. Let it set there and smoke for a while (have a pepsi
break), then come back and start a' scoopin'...it really makes a diference!
You'll save a heck of a lot of solder when you use it, it keeps the solder and
dross separated really well and makes it so easy to throw ONLY the dross away.
-Steve Gregory-
P.S. When did you guys start waving things? When I was there, all that was
there was reflow...that's all we needed to build SIMM's, DIMM's, and the
PCMCIA stuff. So you guys getting into PTH now?
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