Kathie,
Interesting, I guess you have asked the first question, is
this feasible? What are you hoping to gain from this? Was there a certain event,
or group of events that had occurred for management to request this? If they are
simply wanting to establish an SPC program, there are a variety of other areas
where in my opinion it should begin in.
I can't think of too much variable data you would collect in
the cleaning processes, perhaps bath temperatures, pH, time parts are in
solution, bath life (i.e. how often it is dumped and replaced, or replenished),
do you check baume'? ohms? dissolved solids? you already mentioned ionic
testing.
If I were asked to do what they are asking you to do, I would
direct them to other more critical areas. I'm not saying cleaning is not
critical, but I'm sure there are other areas that would provide more useful
areas for improvement.
Franklin D Asbell
Network Circuits, Inc.
Irving, Texas
Hi folks,
I have 3 cleaning processes for
cleaning assembled printed circuit
assemblies - in-line semi-aqueous, batch
vapor degreasing, and good old hand
cleaning with various solvents.
My
management is requiring me to develop an SPC application for cleaning.
This
application should include the use of variable data (actual measurement
of a
parameter rather than pass/fail, good/bad). The measurement should
be
something the average assembler can measure and chart with a minimum of
fuss
and muss - in other words, keep it simple and inexpensive.
Right
now, the only measurement we can do fairly quickly, is an ionic
contamination
test (old Alpha Omegameter). I realize that this test is
really more
qualitative than quantitative even though it produces a number.
I have a
few questions of my esteemed colleagues out there in the
virtual
factory:
1. Do any of you have SPC
applications on your cleaning systems? If
so, what are you measuring
and how often?
2. Is this even
feasible?
Thank you for any help you can provide.
Kathie
Lambert
Process Development Engineer
Northrop Grumman
Baltimore,
MD
410-765-9746
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