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March 1999

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Date:
Sat, 13 Mar 1999 14:22:22 -0600
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Finished profiling this morning for a particularly obstinate board. Couldn't raise
the nozzle as many of you suggest (.050" to .100, or 1mm), and SRT promotes,
because of dense population around every associated rework part. The escaping
heat is too much. However, we did get good removes (TC'd and verified), raised
the place and reflow time/temp profile to 275/250/55/15 for top, bottom, reflow,
and additional reflow - respectively.

This profile worked for all but two parts on the board. The 183 times just
touched 100 seconds, 205 times at a little less than 45 seconds, and an overall
delta of about 10 degrees C. with TC's in all four corners on remove.

I now want to know how many of you have the new nozzles not requiring lifting
off the board surface. If you do, how do they work. I have ordered a sample for
test but will not receive it for another week. Any tips on the new 40mm,
especially, are appreciated.

Also, I have given up on worrying about the force settings without mechanical
feedback to the computer. If 0 = 35 grams, so be it. I'll do some other
modifications if lesser force is required - especially when pasting.

Thanks again and enjoy,

Earl Moon

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