Richard
To answer your question fully would require a book as you do not specify
which aqueous process and which no-clean process or, for that matter,
which soldering process. To take the mainstream products, very briefly,
no-clean requires lowest capital investment and smallest production
floorspace footprint. Because its operating window is much narrower, you
can expect to require more inspection/retouching. Water-soluble
chemistry, OTOH, is much more forgiving in the soldering process,
improving reliability, but the cleaning process is critical, requires
the right equipment and may require effluent pollution control. There
may be problems applying conformal coatings with no-clean, but not with
correctly-processed aqueous. No-clean requires better incoming quality
control of bare boards and components. Experience with companies doing
both or having changed from one to other has shown that overall costs
(component purchase through to finished, tested product) vary from
aqueous process being anywhere from 5% cheaper to 50% more, not counting
component costs, the median being probably around 10% more.
End-product reliability is very product-dependent. One rule of thumb:
the easier the soldering process with a no-clean flux/paste, the lower
the reliability of the finished product. Reason: active flux materials
generally leave the most active residues, causing potential failure
mechanisms. Corollary: if you wish to use a no-clean technique AND to
have a good reliability under bad conditions, you require to choose your
products (including components) very carefully, indeed.
Obviously, this short summary is full of generalities which, no doubt,
will cause others to rise up in arms when taken out of context. If you
provide more exact details of your requirements, no doubt we can become
more specific.
Brian
PS When posting new threads, please put in a subject, because those
members who sort by threads have a hodgepodge of different subjects
within a single no-subject thread.
richard wiltron wrote:
>
> Dear Tech-Net Member,
>
> What are the big differences (quality, cost...)
> between an Aqueous Cleaning and No Clean SMT
> processes.
>
> Your help in this subject is greatly appreciated!!!
>
> Thanks,
>
> Richard
>
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