Steve: The generic name for the chem-film is a conversion coating, and in the old days, (3 months ago, maybe) pre-ROHS, they were chromate conversion coatings, and carried such trade names as Alodine, and Iridite. However, me thinks people is running from true chromate conversion coatings, to subtituted versions, which, and I am sure this surprises you, are generally not as good!
(We used those nasty old chemicals for a good reason, they worked well!)
Unclear what happened on the part pictured, but I would ask if there has been a change in the manufacturing process to a non-chromated conversion coating.
And incidentally, the conversion coatings (Chromated, or not) are not very good protection from either acid or alkaline solutions, the treated parts beat bare aluminum, but that is easy to do, as bare aluminum is attacked by hot water.
I would predict that most aqueous, and some semi-aqueous cleaners would give you this sort of problem. Do you know the pH of your cleaner? If it is 11+, you have a potential problem.
Good luck,
Rudy Sedlak
RD Chemical Company
Stephen Gregory <[log in to unmask]> wrote: Hi All!
We have a series of boards that we build here, that we've been building
for years and years.
These boards use a 320-pin right-angle male connector that has an aluminum
chem-filmed body.
After building the last batch of boards, we have 5-assemblies that have the
worst looking chem-film coating on the connectors I have ever seen. Check out:
http://stevezeva.homestead.com/files/Chem_Film_Gone_Bad.jpg
I'm not a chem-film guru by any means, but I have a hard time believing that
anything in my process caused this appearance. Chem-film conversion coatings
are permanent aren't they? I mean the only way to remove them is mechanically,
or etch them, right?
These boards were wave soldered with a RMA flux and cleaned in Kyzen Aquanox
4512P.
Anybody seen this before and know what might cause this?
Stephen Gregory
Senior Process Engineer
LaBarge Incorporated
Tulsa, OK 74146
(918) 459-2285
(918) 459-2350 FAX
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