Message
Prasad,
I have been following this topic with interest.
However, I was not able to see the photo.
Can
you share that photo with me at my address as an attachment.
Victor,
Could this be
an example of the 'phase separation' problem with the flame retarded resin
formula?
Hello
Prasad,
Thanks for the off line photo. It was the "thousand words".
Based on the etch profile of layer two, the construction appears to
be a "cap foil" construction, thus prepreg was used in the construction of
the outer layers which fits with my first thoughts. I cannot see any
evidence of the effect in the small area or core material that is in view.
If the effect is an intrinsic artifact of the material, I would expect to
find it everywhere and not just in the prepreg zone.
I confess that
I have not seen anything exactly like it before but I am still leaning
towards my earlier thoughts regarding contamination of some sort in and
between prepreg layers (perhaps it is simply moisture in the prepreg as
polyimide is quite hygroscopic).
I am not an expert is resin
formulations and thus would defer to Brian's comments which make sense to me
but I believe that EDX elemental mapping analysis would find bromine if it
is in fact present and dominant in the voided areas. You might send your
photo to Steve Zeva to have him post on his website and let others take a
look and share their thoughts.
Best of luck in finding cause and
resolution.
Joe ---------------------------------------------------
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