Where is it stated that the conductive pattern can not have any exposed
copper on the vertical surfaces? Is that any empirical data that supports a
failure mode if there is exposed copper on the vertical surfaces of a
conductive pattern? I have searched MIL-STD-2000, NASA-STD-8739-2 and
NASA-STD-8739-3 but can only find that it is allowed. Where I work those
with PhD's worry about exposed copper on the vertical edges of the
conductive patterns and are scared to allow to move forward because of
possible failure modes with a deep space launch. For my limited knowledge of
metallurgy: after copper is exposed to moisture and oxygen, corrosion takes
place only on the surface and does not migrate any further. I do have access
to NHB5300 to see if exposed copper was not allowed.
Gary Bremer
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