I see quite a significant practical difference in crack initiation for
the roll direction vs. transverse.  I'm sure specifications are
available which support that.  So the metal will withstand bends on
either axis, but more severe bends for those with the axis of the bend
at right angles to the roll direction.

An additional element you need to be aware of is that you don't want
any plated metal to get onto the flex in the vicinity of the bend:
Doing so just about completely destroys the malleability of the
conductors.  Fortunately, most rigid/flex designs don't have plating
added to the flex layers since its uncommon for vias to terminate
there.

Wayne Thayer

>>> [log in to unmask] 6/1/2006 9:43 am >>>
For rigid-flex boards fabricated, is it recommended that the copper
conductors be aligned with
the copper grain direction for bend-to-install applications?   Would
the copper foil grain direction have an impact on tear strength on
bend-to-install applications.

Any experience with this issue?

Thanks

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