Brian,
You have certainly opened the forum for the larger question of the "need" of
cleaning.
Our surface mount reflow and wave soldering operations use water soluble
fluxes and obviously there is a definite need to clean when using these
aggressive fluxes.
However, for secondary operations (Hand soldering, soldering stranded wire,
etc.) we use Rosin cored solder and RMA fluxes for these operations. Most
programs that we work with require ionic contamination testing so, cleaning
is necessary. In addition, it is good practice to have clean assemblies when
conformal coating needs to be applied.
Since Freon and similar products have been banned, IPA has become the
solvent of choice for these applications even though the IPA only "smears"
the material around. It does allow us to "get by".
I have used Flux-off CZ in limited applications. It removes flux residues
nicely but its drawback is the high cost.
So, there is a definite need for cleaning. Use of no-cleans requires
pristine parts, boards and has a tight process window. For me it's not a
practical choice. It can't be used everywhere just as water solubles can't
be used everywhere. So IPA has become a popular choice only because there is
nothing else when dealing with rosin fluxes even though it's marginally
effective.
Any suggestions for an alternative would be welcomed.
Bill Kasprzak
Moog Inc., Systems Group, Process Engineer
-----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: Friday, July 02, 2004 6:40 AM
To: [log in to unmask]
Subject: Re: [TN] cleaning solvent
Despite popular belief, IPA and other light alcohols are not good
solvents for removing flux residues. However, I cannot answer your
question without knowing a lot more about your products and the
flux/paste used, quantities, equipment etc. However, my first question
is: Are you sure you **need** to clean? Would not a "no-clean" process
be more suitable for your products? Please give your technically
justified reasons for cleaning.
Brian
Murulidhara wrote:
> Dear Technetters,
>
> I want to know what are the better solvents to clean PCB assemblies better
than IPA.
> Also give the sources.
>
> Thanks in advence.
>
>
>
>
>
>
>
>
>
>
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