In a message dated 00-03-31 03:03:48 EST, you write:

<< It seems that the 'oxide alternatives' all have a problem
 processing rolled copper (RA), as e.g. used fore some flex
 constructions. Due to the different structure, there is hardly
 any coloring, and the surface structure must also be quite different. >>

The reason for the different "look" is that oxide alternatives, unlike oxide,
attack the copper at grain boundaries. Oxide alternatives do very well with
the columnar grains of ED & HTE foils, and with the equiaxial acid copper
deposits seen with buried via layers.  The coating on RA foil varies, as
different RA foils have different final grain
structures.  It is seen that the amount of annealing is significant in
this respect.  With many RA foils, the oxide alternative coating is
irregular, paler than
usual.

But it bonds!!!  Some flex and flex-rigid customers who run the
process,  are happy with it.  Some customers have received Military
approval for flex which is bonded with oxide alternative.  So, flex and
flex-rigid
users are NOT stuck with oxide after all, which is good because they suffer
more from the limited material compatibilities (sensitive to hot alkali) of
oxide than most
fabricators.  If cosmetic issues become important, shopping around for RA's
which will coat more uniformly should resolve the problem.

Denny Fritz
MacDermid

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