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From [log in to unmask] Sat Apr 27 15: |
20:02 1996 |
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We have recently experienced an unusual occurence in four lots of
hardware. We have seen lifted pads, cracked internal foil (n-1) and
plating separations. The boards have ranged from eight to twelve
layers and run approximately 0.066 to 0.074 inch thick. These are not
unusual or complex designs just standard plated-through hole
technology. We are using difunctional 0.055 and 0.012 laminate
predominantly one ounce, one board two ounce.
We procure our laminate with HTE on all internals and standard ED for
externals. We had made this change approximately 6-7 years ago and
have not seen a crack since on internals. We tried everything under
the sun and couldn't get the HTE to crack. As most of you know we are
experiencing a labor dispute and our production has been limited. We
have seen this on small number of lots but if we were in full
production we could have a major disaster.
During microsectioning we have also seen some grain structure variance
in the appearance of the HTE copper. The laminate and foils have been
verified to be HTE according to the vendors.
We have performed Tg testing (133 to 141), plating ranges from 0.016
to 0.023 in the hole, elongation from 16.0 to 20.0%, tensile strength,
temperature exposure and we can find no concrete defect cause.
The vendor has reported a phenomenon "Stress Grain Boundary Condition"
which they are looking for the report.
Does anyone have a input on the causes, identification or corrective
action for this "condition"???? I really could use some input and
assistance.
Please respond ASAP!!!
Boeing Defense and Space Group
Roxanne Tovey
(206) 773-7336
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