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Frequently Asked Questions: Equipment
Optimization
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Q. Any recommendations to send me down the right path in a transition
to a new wave solder machine from the dog I have now?
A. Two return questions - are you transitioning to a nitrogen
based wave solder and is your present system nitrogen based?
If you are making the transition, and your present system is
not nitrogen based, then screening with your present machine
would be a waste of time. You could get the best performer in
air, but not nitrogen.
You might consider using a neutral site for development, if you
wish to transition to nitrogen.
If you are looking for low solids fluxes, Kester 951 should be
one of the ones you look at. The Alpha SLS-65 is another good
one. Mutlicore X33-04i is another. We don't think there is such
a thing as a good flux
or a bad flux, but you have to find the one that works best with
your mix of parts. You want a halide-free flux, qualified to
J-STD-004. We
would not recommend looking at a flux unless it is so qualified.
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Q. How do I choose the best flux or cleaning option for my application?
A.
Depends on the application. In general, you wish to minimize
the amounts of harmful residues present on the assembly. Harmful
materials are most
often the halides, such as chloride, so the fluxes chosen should
be halide free, or the cleaning chemistry should be effective
at reducing chloride
and bromide. While we are not in the business of selling cleaners,
if you don't know where to start looking at cleaners, start with
Envirosense Envirogold 816 or Kyzen Aquanox SSA. Both are excellent
cleaners and not harmful to assemblies. Another consideration is the tolerance,
or intolerance, of your components to cleaning. If you have parts
which are water intolerant,
then aqueous or semi-aqueous cleaning is a problem. Such water
intolerant parts can be added later. In these cases, some cleaners
can be rinsed
with isopropanol rather than water. The choice of cleaner also
depends on whether you are going to be doing high volume in-line
cleaning or low-volume
batch cleaning.
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Process Control
Q. What are the critical parameters of my new
manufacturing process?
A. Depends on the process. We have found that many
process problems can be traced back to a few critical areas:
bare board residue levels, solder mask type and cure levels,
flux deposition and
flux type, and the efficiency of a cleaning operation. What is
most critical is for the process engineer to view the big picture
of the process. Everything
is inter-related and every step has an effect on the end item.
Part of our utility as process consultants is that we do see
the big picture and
understand the interrelationships.
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