In a message dated 02/10/2000 2:24:29 PM US Eastern Standard Time,
[log in to unmask] writes:

>
>  I have a question for the "guru's" of PWB cleaning, and obviously it
relates
> to the new legislation (Montreal Protocol)

??New???

>  which now bans the use of Ozone
>  depleting substances containing CFC based materials.  So, with that in
>  mind...."What are the best "cleaning solutions" (chemicals) to use which
are
>  most effective for removing the flux residuals from PWB's that also has
>  compatibility with a wide variety of different chemicals and materials
such
> as adhesives, connectors, sleeving, wire, inks, epoxies and etc.?"

That depends.  Define compatibility.

> In essence, we all know that establishing a suitable substitute is no small
task, and
>  involves many trade-offs as well.   However, I would appreciate anyone
> sharing  their experience with regard to this endeavor.

Wow, I haven't had an ODS alternative question for three years or so.
Figured it was a dead issue.  When the Montreal Protocol was put into effect
in the late 1980s, and Congress nailed the coffin shut with the Clean Air Act
of 95 (?), most manufacturers saw the writing on the wall and started working
towards alternatives.  In my experience, most military contractors went the
route of staying with high solids rosin fluxes, but changed to alternative
cleaning.  This was driven primarily by the MIL-STD-2000A contracts, which
only got painful if you went to a "non-rosin" flux, like a water soluble or
no clean.  Some tried to go the route of HCFCs, using products such as
Genesolv 2004, but it was not long before the EPA put HCFCs in the same bad
class as CFCs.  Most contractors then transitioned to semi-aqueous cleaning,
such as Axarel or Bioact.

The IPC had a program in place to evaluate alternative cleaning materials and
processes.  The benchmarking of Freon TMS was written up in IPC-TR-580.  A
brilliantly written document (guess who). In Phase 2 of the program, the
benchmark test was repeated for many different cleaning materials and
technologies.  Somewhere in my archives I have the final listing of all of
the products which passed that testing protocol.  EMPF, while still in
Indianapolis, did most of the testing.  You might get copies of those reports
from either EMPF (now in Philly) or from Petroferm in Fernandina Beach,
Florida, who now sells most of the materials on that list.  The Test
Monitoring and Validation Team (TMVT), which I chaired, was disbanded some 4
or 5 years ago due to lack of further testing to monitor.  The IPC also had
several Phase 3 efforts, looking at water soluble flux, low solids flux in
air, and low solids flux in nitrogen, and how they compared to the Phase 1
Benchmark.

While the move from ODS materials was painful for most, I think it produced
better hardware in the end.  Freon was not really a very good cleaner, but it
had a good blend of properties.  I see much better cleanliness levels now
from saponified cleaning than I ever saw from Freon or Trike.  The change
forced most manufacturers to REALLY look at their process and understand the
materials and materials compatibility issues involved.

Bottom line:  if you asked me today what one method would I invest in as an
ODS cleaning alternative, I would choose aqueous cleaning with deionized
water (140F min) with the addition of a good saponifier.  Contact me off line
if you are interested in my saponifier of choice.

Doug Pauls
Technical Director
CSL

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