Well, I don't really have knowledge of the first part of the question, but
that's never stopped me in the past (no comments from the peanut gallery).

I suspect it may have some relation to  MIL-I-46058, the military
specification (inactive for new designs) for conformal coating.  In the
spec, it references the following items:
FED-STD-141:  Paint Varnish Lacquer and Related Materials, Methods of
Inspection, Sampling and Testing
FED-STD406:  Plastics, Methods of Testing
MIL-STD-202: Test Methods for Electronic and Electrical Components
(contains a fungus resistance test)
ASTM-G-21:  Recommended Practice for Determining Resistance of Synthetic
Polymeric Materials to Fungi.

I suspect the ASTM method would have the most information.

FR-4, to the best of my knowledge is non-nutrient, as are many polymeric
materials for electronic assemblies.  We consider FR-4 to be fungus
resistant.
If the assembly is conformally coated with a non-nutrient conformal coating
(such as those 46058 or CC-830 qualified), then the assembly should be
non-nutrient as well.   We have used a solvent based acrylic for many years
and as long as components which are not specifically non-nutrient are
covered with the coating, then there is no fungus concern.  It helps that
the coating has a high level of toluene, which kills fungus spoors on
contact.  If you are using some other form of solvent carrier where fungus
spoors might not be killed, it might be a different matter.

Doug Pauls
Rockwell Collins.

A mushroom walks into a bar and orders a beer.  The bartender says "We
don't serve your kind here". The mushroom exclaims "Why not? I'm a fun gi".
(Couldn't resist).




                      Edwin Louis
                      <Edwin.Louis@L-3C        To:       [log in to unmask]
                      OM.COM>                  cc:
                      Sent by: TechNet         Subject:  [TN] Materials Inert to Fungus and Fungus Nutrients
                      <[log in to unmask]>


                      09/03/2003 10:11
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to
                      Edwin.Louis






I had a copy of some spec. that listed at the beginning suspected Fungus
Nutrients, known non-nutrients and known nutrients. It gave class of
compounds and suggestions
as to what catalytsts were suspected of producing nutrient polymers. Does
anyone know what this spec. is that has this info? Also, is FR4 a fungus
nutrient or
non-nutrient? Does a non-nutrient conformal coating protect a non-nutrient
material it is coating from fungus growth?

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