Bob Mesick offered to design and get built a solder pot into which 
     solder which had become laden with copper could be transferred so as 
     to allow the copper-tin IMC to rise to the surface so that it could be 
     scooped out.  If such a pot were to be built, then it seems to me that 
     it would be good to have something a little better than a ladle to 
     transfer the solder from pot 1 to pot 2 and back again.  How about 
     including a pump with heated transfer line?
     
     I am curious about the need for such a machine.  First, how many 
     operations are there that keep the wave solder machine running so 
     consistently that it can't be "shut down" (i.e., not operated, so that 
     the solder can be allowed to sit just above its liquidus temperature) 
     for a day every so often?
     
     Second, why does the copper have to be removed?  Apart from the fact 
     that J-STD-001 sets a limit on the copper in Table 5-1, the worst that 
     can be said for the presence of the copper in the solder is that it 
     makes it look kind of funny.  If ignored, the copper level in the 
     solder does not continue to rise but reaches a steady state, since 
     fresh solder must continue to be added to the pot.  Excess copper in 
     the solder is not a defect per Table 11-1, and in this standard, 
     "'must' and 'shall' are used to emphasize characteristics that must be 
     considered during the development of the process control program" 
     (Para. 1.5).  The way I read this sentence, if the process control 
     program has determined that copper in solder is not worth controlling, 
     it doesn't have to be.
     
     Gordon Davy

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