[SI-LIST] Re: Core or prepreg between signal and plane layers
- From: "Rose, Michael" <mrose@xxxxxxxxxxxxxxxxx>
- To: "johan.lans@xxxxxxxxxxxxxxx" <johan.lans@xxxxxxxxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Fri, 19 Oct 2012 17:04:10 +0000
Johan, This is the common foil arrangement with B-stage on top and bottom.
Holding impedance tolerance is affected when referencing to plane separated by
prepreg. Lee Ritchey has been beating the drum on this for ages. The fab can
control etchback to center the error within the likely variation in prepreg
thickness determined when qual'ing the material. In my experience, holding
+/-10 is not generally not a problem - maybe +/- 5% is another story?
Mike
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Johan Lans
Sent: Friday, October 19, 2012 12:53 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Core or prepreg between signal and plane layers
Hi
I'm working on a 16 layer board for video processing. There will be 100 Ohm
differential pairs for 3Gbit digital video signals. Stackup is signal on top
layer, 2nd layer power, 3rd gnd, 4th signal, 5th signal, 6th power, 7th gnd and
so on.
The manufacturer of the board wants to put prepreg between lyr 1 and 2, 3 and 4
etc and core between 2 and 3, 4 and 5 etc. A collegue of mine claims that this
stackup will give a less uniform impedance of the diff pairs, since the
distance from signal to plane layer will vary more due to the initial softness
of the prepreg. The manufacturer will produce a board with core between signal
and plane for a higher price, since layers registration will be more difficult.
Does anyone know how much this effect matters, and if it's worth the money to
get the more difficult to produce board?
/Johan
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
_______________________________________________________________________
This e-mail and any files transmitted with it are proprietary and intended
solely for the use of the individual or entity to whom they are addressed. If
you have reason to believe that you have received this e-mail in error, please
notify the sender and destroy this email and any attached files. Please note
that any views or opinions presented in this e-mail are solely those of the
author and do not necessarily represent those of the Curtiss-Wright Corporation
or any of its subsidiaries. Documents attached hereto may contain technology
subject to government export regulations. Recipient is solely responsible for
ensuring that any re-export, transfer or disclosure of this information is in
accordance with applicable government export regulations. The recipient should
check this e-mail and any attachments for the presence of viruses.
Curtiss-Wright Corporation and its subsidiaries accept no liability for any
damage caused by any virus transmitted by this e-mail.
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
