Hi Steve - as long as you don't exceed the various element limits in the 
solder pot per the IPC JSTD 001 specification, there is no reason you 
can't just leave that leadfree solder in the pot. Mike posted the 
calculations so it looks like you would be in good shape. One thought - I 
would expect that leadfree solder would be worth more to the recyclers due 
to the silver content so it might be worth the effort to drain that last 
200 lbs for recycling purposes.  Seems strange, never heard of someone 
leaving 200 lbs of solder in a pot.

Dave Hillman
Rockwell Collins 
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From:   Steve Gregory <[log in to unmask]>
To:     <[log in to unmask]>
Date:   03/13/2013 07:23 PM
Subject:        [TN] Extra Lead Free solder in wave solder pot...
Sent by:        TechNet <[log in to unmask]>



Hi all!

My new employer has purchased a used Vitronics-Soltec 6622 wave solder 
machine that supposedly still has 100-200 lbs. of lead free solder in the 
pot because they were told that it was difficult to remove. My new 
employer is intending for this wave to be run as a leaded machine.

So, what do you think about leaving that residual lead free solder in the 
pot and just filling it up with 63/37? I haven?t seen the machine yet 
(I?ve yet to get to Boise), and I?ve never seen the inside of a empty 
?6622 wave solder pot, so I don?t know why it would be difficult to empty 
the pot completely. I?ve always been able to get all of the solder out of 
all the pots that I have ever emptied. Does it have immersion heaters that 
are mounted in some sort of structure at the bottom of the pot that 
prevents all of the solder from being removed?

I?ve been told that a sample of the solder that was left in the pot has 
been sent to AIM solder for analysis, so we?ll know exactly what it is. I 
know that most lead free solders are mostly tin, so would it be just a 
matter of adding extra lead to the pot to bring everything into 
compliance? 

I definitely plan on getting the solder analyzed once the pot is filled 
and before any product is run, but I want to know if this is a bad idea? I 
don?t want to load up the pot with solder and learn later that the pot is 
contaminated and has to be drained. Sorry for all the questions but I have 
never taken a wave that has been run as a lead-free machine and then be 
converted to a leaded machine...plus I?m not yet as familiar with the pot 
and heater configuration of the Soltec?6622 machine as I would like to be. 


If it was the other way around (leaded ----> Lead-free) I wouldn?t even be 
thinking about it, NO WAY!

Steve

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