The file is now posted on Steve Gregory's site. Go to
[log in to unmask] <http:[log in to unmask]> and
click on Flexdata.pdf
Actual impedance is 50.4.
We cannot use a stripline because then the part will not flex properly.
We are looking into the x-hatch. This may be the issue.
The pads are directly connected to a mating board by solder reflow but
the testing is done before assy.
Pad plate or selective plate means the copper is plated up only around
the holes/vias - not on the tracks - so the tracks are consistently
.0007 thick.
Regards Steve Kelly
PFC Flexible Circuits Limited
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of JaMi Smith
Sent: Friday, January 24, 2003 3:27 PM
To: [log in to unmask]
Subject: Re: [TN] FW: HI - SPEED NOISE PROBLEM
Steve,
Just what exactly do you mean by the Subject "HI - SPEED NOISE PROBLEM",
and the statement "I have a question about noise levels at high speed
on a flex circuit." ?
Just exactly what kind of "noise problems" or "questions" are you
talking about: Crosstalk; Interference; Radiation / EMI?
So far it seems that you all you have described is some pretty normal
"attenuation" (loss), and possibly an issue of some "resonance" with the
length of some of the conductors.
You state that your impedance is "approximately 50 ohms", what does your
network analyzer say that it really is.
How good a ground plane do you really have under the traces. Maybe that
could be better phrased as asking how large are your openings in your
cross-hatched ground plane.
I assume that you do realize that since you are using microstrip (one
ground plane)instead of stripline (two ground planes with signal in
between) that your are going to "radiate" your signal to some extent no
matter what you do, and that your signal is also susceptible to
interference from other sources.
Are you using the flex as some form of interconnect?
What are the "pads" for that are selectively plated? Are these some kind
of contact for a connector, or are they for mounting parts?
Has Steve Gregory been able to post your pdf, and if so, what is the
link.
JaMi Smith
----- Original Message -----
From: Steve kelly <mailto:[log in to unmask]>
To: [log in to unmask]
Sent: Friday, January 24, 2003 11:07 AM
Subject: [TN] FW: HI - SPEED NOISE PROBLEM
PFC Flexible Circuits Limited
-----Original Message-----
From: Steve Kelly [mailto:[log in to unmask]]
Sent: Friday, January 24, 2003 12:09 PM
To: IPC ([log in to unmask])
Subject: HI - SPEED NOISE PROBLEM
Dear Technetters:
I have a question about noise levels at high speed on a flex circuit.
The circuit is:
1) surface microstrip design (.004 tracks on one side - x- hatched
ground plane on other)
2) impedance is approx. 50 ohms
3) construction is: .0005 kapton
.0005 adhesive
.0007 RA copper )
.002 kapton ) DuPONT AP
.0007 RA copper )
.0005 adhesive
.0005 kapton
4) part is pad plated/selective plated
5) finish is immersion gold over electroless nickel
6) circuit is less than .5 inches long
When we measure the S parameters of the 50 ohm trace, the bandwidth
starts dropping at 6 GHZ , peaks at 13 GHZ and then drops - I have a
pdf. file which I can send off-line or post it to somewhere?
Any thoughts?
Thanks
Steve Kelly
PFC Flexible Circuits Limited
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text
in the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for
additional information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------