Sorry about the delay in my response, but I've been on the road all week
and just saw your posting.

The design as you describe it will have up to 27% Strain in the Copper.
This may be sufficient to start a crack in even one bend cycle. It will
cause some necking (reduced cross section) of the traces that may also
be an electrical problem for sensitive applications.

You can quickly analyze your options with my flex analysis software
located at:
http://www.geocities.com/CapeCanaveral/Launchpad/9641/program/program.html

Andy Magee
Flex Guru - Consulting
[log in to unmask]
(937) 435-3629



Eric wrote,
We're currently working on a design which entails a leap into the
unknown for
us. I'd like to know if anyone's been here before and what they found.

I've got a very small Flex which needs folded up in order to fit it into
a
tube, Once the flex is inside the tube everything is potted and so the
flex
never moves again. In order to get it into the smallest diameter tube we
need
to put a sharp, permanent bend into the flex. Has anyone done this
before and
did it cause cracking in the tracks - the bend will always be
perpendicular to
the tracks.

The spec for the flex is:

double sided
1/2 oz copper
0.002" pyrolux (polyimide) substrate
0.25mm inner bend radius.
Epoxy coverlay top and bottom.




Eric Christison

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