Wayne,

   You make a statement of "GRAIN DIRRECTION and how critical it is to functionl assembly but you don't explain how to accomplish that task".   Are you at liberty to share your valued experience?

Victor,


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Wayne Thayer
Sent: Monday, January 28, 2013 7:09 AM
To: [log in to unmask]
Subject: Re: [TN] Flex design guidelines / assembly guidelines

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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