[PCB_FORUM] Re: Routing PCI Express on Flexi
- From: <george.h.patrick@xxxxxxxxxxxxxx>
- To: <icu-pcb-forum@xxxxxxxxxxxxx>
- Date: Mon, 3 Apr 2006 16:50:38 -0700
How tight do the bends have to be? We commonly run impedance controlled
diff pairs on flex, but a real tight bend radius can delaminate the
layers and play games with the impedance. We usually keep a very loose
bend radius and have less problems. We usually use embedded microstrip
(two copper layers (ground plane and signals), with 3 dielectric layers,
but higher layer counts and stripline configurations might keep the
trace widths more manageable in your application....
--
George Patrick
Tektronix, Inc.
Central Engineering, Engineering Design Services
P.O. Box 500, M/S 39-512
Beaverton, OR 97077-0001
* 503-627-5272 (voice) * 503-627-5587 (fax)
<http://www.tektronix.com/>
http://www.tektronix.com <http://www.pcb-designer.com/>
http://www.pcb-designer.com
"Off-Grid and Proud of it!"
-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of richard moffat
Sent: Monday, April 03, 2006 16:03
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Routing PCI Express on Flexi
Hi
It will be static and it will have bends.
Signal frequency of 1.25 GHz, rise time of sub 100ps, maybe around
(gulp) 50ps.
Probably just around the garden variety 50 ohms. However, I'm a bit
cautious about the skin effect loss.
>>> peterp@xxxxxxxxxxxxx 4/04/2006 10:45 a.m. >>>
Will it be a dynamic or static FPC? Does it need to have any bends in
it?
Peter
_____
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of richard moffat
Sent: Monday, April 03, 2006 3:38 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Routing PCI Express on Flexi (I am still here too!)
Hi all
As this list has a many high-flying people, I thought I'd ask a
high-flying question.
I've been asked to look at routing PCI Express on flexi. I believe that
this would be extremely difficult, due to impedance control. The
flexiwould have to be quite thick, and thin traces would be too lossy.
Has anyone done this at all??
Cheers,
Richard
__________________________
Richard Moffat
PCB CAD Manager
Allied Telesis Labs
ph. +64 (3) 3393000
richard.moffat@xxxxxxxxxxxxxxxxxxx
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