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August 1997

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Fri, 15 Aug 1997 17:04:33 -0600
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     Some additional comments: 
     
     You should also check to see that you are not over drying the flux.  With 
     newer machines come more preheat capability, and a tendency to over heat at 
     preheat.  
     You didn't say what type of flux you were using, but if it's a rosin based 
     flux, the PWB's should be entering the wave just slightly tacky (very 
     slight).  Test this with a glass plate (or even better an actual 
     assembly)with the wave shut off.
     
     I agree with the previous Technetters definition of the ideal wave:  
     Flowing toward the load end and static toward the unload end.  When the PWB 
     contacts the wave, it should just push the solder over the edge.  It helps 
     to try to match the flow over the dam with the PWB speed.
     
     Check everything (especially the basics: conveyor level, pot level, 
     conveyor angle, etc.).  I assume you are running some sort of M.O.L.E. or 
     other temperature logger?  Make sure you are attaining the proper preheat 
     schedule per the flux manufacturers specs.
     
     Has this assembly been run successfully on another machine?  If so, then 
     it's probably not design, lead spacing, etc.  I would look at design last 
     (unless it is an obviously poor design, but that never happens right?).
     
     Hope this helps!!
     
     Steve McBride
     Manufacturing Engineer
     Frontier Electronic Systems Corp.
     (405)-624-5281
     


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