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November 1999

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Subject:
From:
"Collins, Graham" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 30 Nov 1999 13:03:35 -0400
Content-Type:
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text/plain (173 lines)
Alberto
That's a question that will take more than a few emails to properly cover.
The choice of a flux should involve many other inputs, such as:
 - customer requirements (mine dictate flux type)
 - customer perception - will they mind a flux residue?
 - equipment available - some wave machines won't to well with low residue
 - end use of the product (space, office, toy?)
 - other chemicals used (potting, conformal coating, etc.)
 - solderability of your parts
 - incoming cleanliness of your parts
I'm sure others could add to this list.

As with most things in life, there are tradeoffs in cost, ease of assembly,
environmental impact...

Low residue is great in that you may be able to eliminate your cleaning
process - an obvious savings!  But make sure your homework is done first,
it's not a "drop in" change and the pitfalls can be hidden and expensive.

regards,

Graham Collins
Process Engineer,
Litton Systems Canada, Atlantic Facility
(902) 873-2000 ext 6215

-----Original Message-----
From: Alberto Callo [mailto:[log in to unmask]]
Sent: Tuesday, November 30, 1999 12:34 PM
To: [log in to unmask]
Subject: Re: [TN] Wave Soldering


So what process is better?  No-clean, water soluble, etc?

Brian Ellis wrote:
>
> Dave
>
> As a pedant, I may go along with you on this, at least partially. I have
used the
> term "no-clean" (always in inverted commas) for both material and process.
"Low
> residue" is not necessarily the same, though. Many people use RMA with 25%
or more
> solids as a "no-clean" and certainly the DIN F-SW32 fluxes, generally
15-30% solids,
>
> must be "no-clean" because you cannot clean them for love nor money. And
no solder
> paste can be classed as low solids, as 50% or thereabouts of the stuff (by
volume)
> is low-volatility chemistry. OK, the residues may be neatly transparent
and matt, so
>
> you have difficulty seeing the residues but they are there.
>
> My personal definition of a "no-clean" flux/paste is one where the
residues do not
> have to be removed for selected and qualified applications. A "no-clean"
process is
> one where the post-soldering residues are not removed.
>
> Again, as a pedant, I think your message has revealed a requirement for a
new
> terminology but, where there is already a firmly entrenched one, neither
you nor I
> will ever budge it.
>
> Best regards
>
> Brian
>
> [log in to unmask] wrote:
>
> > Hi TechNet! Just to add a bit of wordsmithing to Brian's internet
references.
> > The electronics community has created itself a technical "cultural" bias
which
> > is going to take some time to undo. We have interchangeably used "no
clean" to
> > describe both the material and process aspects of a product (e.g. flux).
We
> > should be using the term "low residue" to describe the material
characteristics
> > of a flux - how much flux residue is left on a printed assembly after
soldering
> > processing. We should be using the term "no clean" to describe the
process
> > characteristics of a flux - is it removable  or non-removeable after
solder
> > processing. The use of the term "no clean" for both the material and
process
> > aspects is very confusing to the folks on the factory floor because they
can
> > unintentionally misinterpret the product labeling as permission to no
longer
> > clean an assembly which may not be the case. I also know very few
process
> > engineers who are keen on having someone unfamiliar with their soldering
process
> > to suggest that a "no clean" flux is ok.  The description of "using a
low
> > residue flux in a no clean process mode" leaves little room for
> > misinterpretation. Ok, enough soapboxing.
> >
> > Dave Hillman
> > Rockwell Collins
> > [log in to unmask]
> >
> > Brian Ellis <[log in to unmask]> on 11/27/99 02:21:23 AM
> >
> > Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please
respond to
> >       Brian Ellis <[log in to unmask]>
> >
> > To:   [log in to unmask]
> > cc:
> >
> > Subject:  Re: [TN] Wave Soldering
> >
> > The United Nations Environment Programme Solvents Technical Options
> > Committee gives an excellent explanation, with the advantages and
> > disadvantages of each, in Chapter 2 of their 1998 Report to the Parties
to
> > the Montreal Protocol. This 200 + page report can be downloaded (free)
in
> > PDF format from the non-commercial committee site at
> > http://www.protonique.com/unepstoc
> > or you may purchase the printed document from
> > http://www.unep.org/ozone
> >
> > Brian
> >
> > Alberto Callo wrote:
> >
> > > Hi,
> > >
> > > I wonder if anyone can explain the difference between NO CLEAN and
Water
> > > Soluble wave solder methods.
> > >
>
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