I have read it. It's a good book. I would still recommend anyone who is
getting into Flex for the first time get a copy of IPC-2223B. This is a
great site
http://www.flex007.com/
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
James, Ron CAR
Sent: Tuesday, July 21, 2009 6:18 AM
To: [log in to unmask]
Subject: Re: [DC] Flex circuit and UL94V-0 requirement
Thanks for the link to the Teledyne design guide. We have not
used flex circuits yet, but I like to know where to get info.
Just in case some one ambushes me with a question, like they
did to Jeffrey. ;-)
What is your opinion of Flexible Circuit Technology, 3rd ed?
http://www.flexiblecircuittechnology.com/third.php
Ron James, CID
-----Original Message-----
From: John Foster [mailto:[log in to unmask]]
Sent: Monday, July 20, 2009 1:52 PM
Subject: Re: Flex circuit and UL94V-0 requirement
There is a plethora of design guides on the web. I have never seen a
class on LAYOUT lots of classes on material, construction etc from the
IPC. Like this event in Crane Indiana.
The one danger I have found with the design guides is when it comes to
dynamic flex
If you have something that is going to move a lot you need to take great
care. I would
Pick up a copy of IPC-2223B and read it from cover to cover.
http://www.tetpct.com/resource.aspx
This is one of the better design guides on the web. But it even calls
out the classic
10X, 6X bend radius. We have found through painful experience that this
does not apply to dynamic flex situations. There are a few rules which
should be followed depending on what you are doing. Pure flex, rigid
flex, book binding etc. All of these rules are covered in IPC-2223B.
But you can get very creative with this stuff.
My fabricator told me a long time ago that putting the Ul callout was
not valid for flex. I have sent him an email for a reminder as to why.
However a LOT of people use the pyralux material from Dupont and they
have a section about Ul. It's the laminate supplier who gets the UL
rating yes. So now I am curious as well as to a proper callout.
http://www2.dupont.com/Pyralux/en_US/tech_info/index.html
But with all of the acrylic adhesive they use I would imagine that its
very flammable.
Flex is polyimide, glue, copper, glue, polyimide, repeat. After I hear
from my fabricator I will let you know what he said.
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
[log in to unmask]
Sent: Monday, July 20, 2009 9:36 AM
To: [log in to unmask]
Subject: [DC] Flex circuit and UL94V-0 requirement
Good Morning,
I have a question that was presented by one of our engineers in regards
to requiring UL94V-0 rating on flex circuits that I hope somebody with
experience doing flex circuits may be able to better answer as I have
only done Rigid boards.
Their question stems from a vendor response to Rigid-flex board design
which was done by an out of house designer, who added a requirement for
UL94V-0. The vendor responded that they don't get UL94V-0 ratings on
Flex circuits because the cost of obtaining the certification was too
substantial.
I typically always call it out on Rigid boards, but as I said, I haven't
done Rigid-flex and my only recourse thus far has been to comb through
other peoples flex board designs, and none have stated the UL
requirement. But that isn't to say it may not be buried in one of the
spec's called out.
Does anyone out there typically call out UL94V-0 ratings on their flex
circuits? Along with this, are there any facilities or courses in
design for flex circuits?
Thanks in Advance!!
-Jeffrey
________________________________
JEFFREY A. JENKINS
SR. PCB/CAD Designer CID+
L-3 COMMUNICATIONS LINKABIT DIVSION
3033 Science Park Rd.
San Diego, CA 92121
Tel: (858) 552-9832
Fax: (858) 552-9487
[log in to unmask]
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