Brian & Juan,
There are a number of Foranes - some are Cholorfluorocarbons like 113 and
others are Hydrochlorofluorocarbons like 141b. HCFC 141b is still legal, at
least in Singapore, until the end of 2004. It is still readily available in
the form of Genesolv 2004 and others.
How poor a defluxing agent are these solvents? They used to be THE thing
for board cleaning until CFC's were banned and everyone then wailed about
how poor the replacements were. I dare say that by now the flux and
cleaning chmistries have been developed to work with each other, but do
todays flux chemistries (especially water soluble RMA's) now render solvent
cleaning ineffective?
I'm joining in this thread because we are trying to bring back on line a
small, aging Solvent Degreaser for very small and light jobs. The volume
does not really justify buying a DI aqueous wash system, but we were going
to buy a batch cleaner before we found the solvent cleaner still in good
working order. We intend to use Genesolv 2004 in it. By light jobs, I mean
for cleaning fewer than 300 boards over a five year period of fingerprint
oils from inadvertant poor handling, flux residues from repairs and mods,
and residues from stripping of Humiseal conformal coating in separate
tanks. Do you think we're wasting our time and should be investing in a
small DI water cleaner instead (in terms of chemistry, not international
protocol)?
Peter
Brian Ellis <[log in to unmask]> 18/11/2002 08:56 PM
Sent by: TechNet <[log in to unmask]>
Please respond to "TechNet E-Mail Forum."; Please respond to Brian Ellis
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cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
Subject: Re: [TN] Flux compatibility and conformal coating.
Juan
The answers to your question are largely treated in the thread 'To wash
or not to wash (again)' started by George Carroll on 16.11.02.
I don't know anything about ROLO or ORLO (for me ROLO is a chocolate
covered toffee :-) ) so I can't make specific comments. However mixing
flux types is NEVER a good idea. It just adds to the composition of the
porridge I talk about in the above thread.
What shocks me, though, is that you talk about cleaning in Forane
(CFC-113). This has not been manufactured since 1995 and is a controlled
substance under the Montreal Protocol. If you have pure CFC-113 from a
stockpile, which is legal if against the spirit of the Protocol, you may
get away with it, although it is a terribly poor defluxing solvent. If
you have a blended CFC solvent, made for defluxing, it is well past its
sell-by and best-before dates. It will certainly not be what you think
it is and will quite likely cause far more harm than good to your
assemblies. If you purchased it after 01.01.96, you have probably
committed an illegal act. I'm not sure, but I believe the USE of
ozone-depleting solvents may also be banned in the EU. I would seriously
suggest you contact immediately the Spanish ozone office and ask for
advice as to how to dispose of it legally. And **please** do not
contribute any more to ozone depletion.
Oh! and all fluxes used for electronics soldering are organic :-)
Brian
Juan T. Marug¨¢n wrote:
> Hi technetters !
>
> Although I¡¯ve read some messages about this matter, let me ask you some
> additional information.
>
> For our class 3 boards (avionics & military), we used rosin fluxes
(ROL0).
> Now, we are thinking about to subcontract the assembly of some type of
> boards. One of the possible subcontractors uses no-clean organic flux
> (ORL0) for wave soldering. No post-solder cleaning is performed.
>
> After this assembly, we have to solder some components/wires to these
> boards so we will use our rosin flux. And, at the end, boards will
> conformal coated with Humiseal (acrylic).
>
> My questions are:
>
> 1.- Can the use of an organic flux (residues) to produce some effect in
the
> solder joints performed later using rosin flux?
> 2.- What happen when these boards are cleaned with CFC solvents (Forane)?
> 3.- Have no-clean flux residues some effect in the quality (adherence,
...)
> of conformal coating?
>
> Thank you from Spain for your help.
>
>
> Juan T. Marug¨¢n L¨®pez
> Production Quality Assurance
>
> INDRA EWS, Sociedad An¨®nima
> C/ Joaqu¨ªn Rodrigo 11
> 28300 Aranjuez - Madrid (SPAIN)
> [log in to unmask]
> www.indra.es
>
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