Tin oxidizes faster than lead. This means that dross has a higher tin 
     content than the solder in the pot.
     
     In a previous job, with a very high dross machine, we regularly added 
     tin to the bath.
     
     Have the dross production and dross composition from that machine 
     checked and compare it with that of the other machines. The tin is 
     probably coming from the dross.
     
     High antimony alloys were used to reduce this differential. I notice 
     that you are using an antimony free alloy.


______________________________ Reply Separator _________________________________
Subject: ASSY: Low Tin Level in Wave Solder
Author:  [log in to unmask] at internet
Date:    1/3/97 3:41 PM


Good Day Everyone!
     
     We just got our solder analysis back (it's from a lab that everyone uses)
for our wave solder pots, and we have one wave solder pot that's low in Tin... 
61.4% to be exact. The recommendation is to add 4.3 lbs. of pure Tin for each 
100 lbs. of solder to return it to the nominal 63%.
     
     My question is; just how in tarnation did we get one wave solder pot low on
Tin? It don't make sense...we use the same bar solder in all our machines, we 
wave solder basically the same kinds of products in all of our machines. By that
I mean we don't have one line waving only gold plated boards all the time, or 
only OSP coated PCB's all the time, etc.. so what gives?
     
     This is the very first time that I've ever had a solder analysis come back
and tell me to put pure Tin into the pot...this is weird. I've had nickel get a 
little high before, but that's about it. We've got three machines and all of the
analysis looks like this:
     
     
                Pot-1           Pot-2           Pot-3
     
Tin             62.4%           61.4%           62.7% 
Lead            Balance         Balance         Balance 
Antimony       <0.005%         <0.005%         <0.005% 
Copper          0.039%          0.048%          0.033% 
Gold            0.017%         <0.003%         <0.003% 
Silver         <0.001%         <0.001%          0.002% 
Aluminum       <0.001%         <0.001%         <0.001% 
Arsenic        <0.010%         <0.010%         <0.010% 
Bismuth         0.001%          0.001%         <0.001% 
Cadmium        <0.001%         <0.001%         <0.001% 
Indium         <0.005%         <0.005%         <0.005% 
Iron           <0.003%         <0.003%         <0.003% 
Nickel          0.006%          0.005%          0.004% 
Zinc           <0.001%         <0.001%         <0.001%
     
     
The analysis was conducted according to specifications in IPC-S-815B. As you can
see, Pot-2 is the "slacker" tin-wise. The only noticable difference that I can 
see between the other two is that the copper content is just a tad higher...does
that have anything to do with anything? Looking at the tin content on the other 
two pots, they're just barely above the limit which is 62.4%-63.6%...is my bar 
solder vendor starting to get tight with the Tin? Any light that anybody can 
shed on this would be 'preciated...
     
                   __\/__
               .  / ^  _ \  .
               |\| (o)(o) |/|
     #------.OOOo----oo----oOOO.-----#
     #          Steve Gregory        #
     #      SMT Process Engineer     #
     #  The SMT Centre Incorporated  #
     #   [log in to unmask]   #
     #________________Oooo.__________#
               .oooO  (   )
               (   )   ) /
                \ (   (_/
                 \_)
     
     
*************************************************************************** 
* TechNet mail list is provided as a service by IPC using SmartList v3.05 * 
*************************************************************************** 
* To unsubscribe from this list at any time, send a message to:           * 
* [log in to unmask] with <subject: unsubscribe> and no text.        * 
*************************************************************************** 
* If you are having a problem with the IPC TechNet forum please contact   * 
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      * 
***************************************************************************

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************