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Reply To: | TechNet Mail Forum. |
Date: | 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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