Hi Louis - yes, as a generalized answer, you will reach a constant value 
provided you are: (1) de-drossing on a regular basis and removing a 
consistent volume; (2) the quantities of assemblies and their surface 
finish is relatively constant; (3) the wave solder pot temperature and 
conveyor speed are relatively constant.  Reaching a constant level of any 
element in the solder pot is a balance of what goes thru the wave solder 
pot and what gets removed in the de-drossing step. We run very little OSP 
boards so the copper levels don't move around much on our solder pot. We 
do run a bunch of ENIG and ImAg boards which ends up coming out in the 
dross provided our volumes stay consistent. You can get some copper to 
come out in the dross but if you are running a heavy volume of OSP boards, 
you might have to take measures to balance copper content. The only time 
we have ever had an element compliance issue was with a mini-wave 
solderpot when we processed a serious volume of gold plated connectors 
which spiked to gold content of the solder pot out of compliance. I have 
been fortunate to never have to drain a solder pot due to a element 
compliance issue.

Dave



Louis Hart <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
03/11/2011 10:06 AM
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Re: [TN] Solder bath analysis. Sn63Pb37 alloy.






Dave et al, let me ask a question about solder pot maintenance about which 
I've been curious for a long time.

If the dross is skimmed off the top of a pot (that is being used for 
soldering or for HASL), will the copper concentration eventually reach 
some (within the limits of measurement error)constant value? My theory is 
that it will.

Louis Hart

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Friday, March 11, 2011 9:31 AM
To: [log in to unmask]
Subject: Re: [TN] Solder bath analysis. Sn63Pb37 alloy.

Hi folks! In the IPC-HDBK-001 Handbook, section 5.3.7, page 62 is the 
formula you can use for calculating how much tin you add to the wave 
solder pot for tin replenishment efforts.


Dave Hillman
Rockwell Collins
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