[SI-LIST] Re: 8 Layer stack up
- From: "Best, Frederick K" <frederick.k.best@xxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Thu, 10 Jul 2003 15:54:35 -0400
Youssef,
You are correct about the lack of good plane capacitance. But with
the 2 plane and 4 signal layers constraint that Nagaraj's 8 layer board
has,
it is more important to have tight coupling between the signal layers
and the current return planes than to have good plane capacitance.
Some form of distributed decoupling capacitance is needed to make up
for the loss of plane capacitance.
As near as I can tell, there are no top and bottom signal layers
in Nagaraj's board. The top and bottom layers must be mounting pads
only. All four of the suggested signal layers (2,4,5,7) have a close
reference plane and the adjacent signal layers are orthogonal to each
other,
both of which reduces crosstalk.
Fred Best
> -----Original Message-----
> From: Youssef Khalife [mailto:youssefk@xxxxxxxxxx]
> Sent: Thursday, July 10, 2003 1:27 PM
> To: Best, Frederick K
> Subject: [SI-LIST] Re: 8 Layer stack up
>
>
> Fred
> Your stack up does not have good plane capacitance for EMI
> and noise margin and also the top and bottom signal layers do
> not have a close reference plane to reduce the cross talk.
> You may need to simulate your stack up using hyperlynx or
> other tools to determine the trace seperation between two
> signal traces on each signal layer.
> Youssef K
>
> >>> "Best, Frederick K" <frederick.k.best@xxxxxxxx> 07/09/03
> 12:24PM >>>
> Nagaraj,
>
> I am not a Guru, but I have a list of stack-ups that have
> collected from published experts and have used them over
> the years.
>
> Is there a reason why your Top and Bottom layers can
> not also be GND planes?
>
> I would not use the stack-up that you show. You should have all
> signal layers adjacent and tightly coupled to a plane. The
> listed second and ninth signal layers violate that.
>
> I recommend the following with your 2 plane and 4 signal
> layers constraint.
>
> Top
> Signal (H1)
> GND
> Signal (V1)
> Signal (H2)
> Power
> Signal (V2)
> Bottom
>
> If possible make the top and bottom layers into GND layers.
>
> Fred Best
> Staff Engineer
> Lockheed Martin
>
> =======================================================
> Hi Gurus,
> What will be the Best Layer Stack up for 8 Layer Board,
> Constraint is we can have only 2 Planes,
>
> Top
> Signal
> Signal
> Power
> GND
> Signal
> Signal
> Bottom
>
> Board Construction with Through Hole Vias
>
> Please Comment on this.
>
>
>
>
> Nagaraj
> Research Engineer
> nagaraj@xxxxxxxxxxxxxxxxxxxx
>
> Embedded Wireless Labs Sdn Bhd
> www.embeddedwireless.com
>
> ------------------------------------------------------------------
> 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 archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
------------------------------------------------------------------
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 archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
