[SI-LIST] Re: Layer Stackup
- From: "Brown, Mike (Austin, TX)" <mibrown@xxxxxx>
- To: <Aubrey_Sparkman@xxxxxxxx>, <mkhusid@xxxxxxxxxx>,<david.kaushansky@xxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Wed, 7 Jan 2004 09:44:58 -0600
My thoughts when I saw the stackup was that 2 more P/G layers closely =
coupled to the planes under signal 1 and 12 would be a good thing. As =
in:
Sig 1
P/G
thin dielectric
G/P
Sig 2
.
.
.
Sig 11
P/G
thin dielectric
G/P
Sig 12
This will minimize the distribution impedance to components mounted on =
either side of the board. Even if the board is single-sided, the second =
PG pair is needed to maintain symmetry in the stackup.
Mike
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of
Aubrey_Sparkman@xxxxxxxx
Sent: Wednesday, January 07, 2004 9:22 AM
To: mkhusid@xxxxxxxxxx; david.kaushansky@xxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Layer Stackup
David,
With this stackup my biggest concern would be the impedance your power
distribution systems.
If you make the dielectric thickness between signal layers > 3X the
dielectric thickness between a signal layer and its reference plane, you
will have less need to use orthogonal routing.
Aubrey Sparkman=20
Enterprise Engineering Signal Integrity Team=20
Dell, Inc.=20
Aubrey_Sparkman@xxxxxxxx=20
(512) 723-3592
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Michael Khusid
> Sent: Wednesday, January 07, 2004 8:56 AM
> To: 'david.kaushansky@xxxxxxxxxxxx '; 'si-list@xxxxxxxxxxxxx '
> Subject: [SI-LIST] Re: Layer Stackup
>=20
>=20
> David,
>=20
> As long as you route orthogonally on adjacent signal layers,=20
> you should not
> have a crosstalk problem at 100MHz. Also, make sure you=20
> decouple the power
> and ground planes well so return currents can move from one=20
> plane layer to
> another without major discontinuities.
>=20
> Michael=20
>=20
> -----Original Message-----
> From: david.kaushansky@xxxxxxxxxxxx
> To: si-list@xxxxxxxxxxxxx
> Sent: 1/7/04 9:40 AM
> Subject: [SI-LIST] Layer Stackup
>=20
> The design I am working has a fairly dense placement. To try=20
> minimize my
>=20
> time in artwork, I would like to add as many routing layers=20
> as possible
> to=20
> my layer stackup. I was thinking of using an 18 layer board of Nelco=20
> 4000-13, with the following stackup:
> Signal1
> GND
> Signal2
> Signal3
> PWR
> Signal4
> Signal5
> GND
> Signal6
> Signal7
> GND
> Signal8
> Signal9
> PWR
> Signal10
> Signal11
> GND
> Signal12
>=20
> The skinniest dielectric thickness is 4 mils, all signal=20
> layers are 0.5
> Oz=20
> copper and plane layers are 1 Oz copper. The fastest signals=20
> are 100MHz,
>=20
> with rise times in 500ps range.=20
> My primary concern is the ratio of 6:12 of plane layers to signal
> layers.=20
> I usually try to design for a ratio of about 8:10 or 9:9. I=20
> know I will
>=20
> have to be very careful about crosstalk on adjacent layers, but other
> than=20
> that, what else should I be concerned about?
>=20
> Thanks
> Dave
>=20
>=20
>=20
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