We are reviewing our alternative cleaning process for application of SPC
methodologies.  The first system to be subjected to the microscope will be
an in-line water cleaner using a water miscible solvent in the wash.  During
the course of our evaluation we will attempt to determine the variation in
the temperature, spray pressure, bath concentration, bath loading, belt
speed, and incoming water quality.  We also intend to attempt to determine
the impact of the variation of each process element as well as determine any
significant interactions.  We have the following questions for comment:

1.  What would be considered a significant variation in the cleanliness level?
     a.  What variation should I see board to board of the same part number
coming off the same process?
     b.  What variation should I see board to board of different part
numbers, but using similiar parameters in the soldering process ?
     c.  Has anybody studied their flux and soldering parameters to
determine when they see large increases in residues due to adverse affects
on the cleanibility of the flux caused by excessive heat and dwell ???

2.  What test methodologies would be best used to determine cleanliness
level for this effort?

3.   Has anyone done a gage R & R on their test methods?

I would also appreciate hearing from anyone who has conducted such a study,
with information on the engineered limits you established.

Your responses are appreciated
Steve Mikell
SCI Systems, Huntsville, ALA
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Steve Mikell, Process Engineer, Soldering & cleaning processes
SCI Systems Plant 13
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