They learnt how it was to be brushed against the grains by Wayne
Inge

On 28 January 2013 14:09, Wayne Thayer <[log in to unmask]> wrote:

> I don't have help for you in finding sources for design guides, but after
> designing/procuring highly stressed (in terms of bend radius) flex designs
> over the past 10 years, I can tell you that it would be a very rare
> fabricator who knows how to tell the grain direction of the RA foil:  Out
> of 18 orders of flex, 9 have come in with the grain in the wrong direction!
>  After I educated those fabricators, they MAY now be able to identify it,
> but I never trust them.  If you need to push things at or beyond standard
> limits, count on learning to read the grain and on the extra time required
> to have a fabricator remake boards.  One fabricator I used last year made
> the initial delivery in May.  By the time they agreed the grain was wrong
> and they re-made the boards, it was October!  They had purchased the
> material from DuPont.  DuPont also did not know how to read grain.  DuPont
> then went to their foil supplier.  I have my doubts on whether any of the
> "education" stuck!
>
> Wayne Thayer
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Coburn
> Sent: Monday, January 28, 2013 7:45 AM
> To: [log in to unmask]
> Subject: [TN] Flex design guidelines / assembly guidelines
>
> T-netter's;
> Can anyone provide direction regarding design and assembly guidelines for
> flexible PCB's / PCA's?
> Thanks in advance for your responses.
> Rob Coburn
>
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