In a message dated 96-10-21 14:09:10 EDT, you write:

> This
>indicated that the chromate conversion coating on the copper cladding had
>embedded in the laminate and was not removed by alkaline etchant. 

Not necessarily!  The Chromium in the conversion coating is present in the
hexavalent state (+6 charge), and is, unless reacted with a metal, pretty
water soluble.  When it gets reduced, as it does in some cleaners, it changes
to the trivalent (+3 charge) where it can react with acid functionalities,
like those that would be found in an epoxy substrate which had hydrolyzed,
instead of crosslinking, which is what you might easily expect in the surface
of an epoxy.  This Chromium would likely form some REAL insoluble compounds,
which would leach slowly into water, making them difficult as hell to remove,
and yet a serious bother, and enough to cause failure in SIR type testing.

There likely is an answer.  The answer, IMHO, would be to use a REAL strongly
chelated alkaline cleaner, perhaps with a kiss of glycol ether, to open
pores, on the panels as a final clean....

 Product
>which passed SIR had this pattern of chrome broken up sufficiently.
>SIR testing measures surface conductivity and detected this metallic
pattern.
> Chrome would not be detected by ionic testing because this test removes
>conductive material from the surface, then measures the conductivity of the
>solution.

Chromium might just leach slowly, on a real low term test..

Rudy Sedlak
RD Chemical
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