hi,

high pH solutions will easily strip chem film.  i don't know if that is
what happened here, but you are right; it is ugly.  maybe one of your
custodians used these to stir a floor cleaning solution.

phil 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stephen Gregory
Sent: Wednesday, December 14, 2005 12:59 PM
To: [log in to unmask]
Subject: [TN] Really Terrible Looking Chem Film...

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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