[SI-LIST] Re: PCB STACKUP

  • From: "Elliott, Martin (UK)" <martin.elliott@xxxxxxxxxxxxxx>
  • To: si-list@xxxxxxxxxxxxx
  • Date: Thu, 22 Jan 2004 17:15:43 +0000

I note that the 2.5 Gb/s differential signals are between 2 planes in this=
 stack.  We are just discussing whether to route on the bottom outside=
 layer to avoid via impedances and stubs on the press fit connectors at the=
 board edge, or to bury them as in this design.=20

Does anyone have any thoughts?

Thanks

Martin

-----Original Message-----
From: Perry Qu [mailto:perry.qu@xxxxxxxxxxx]
Sent: 22 January 2004 15:40
To: mkhusid@xxxxxxxxxx
Cc: 'Nosovitski, Alexander (Contr) '; 'si-list@xxxxxxxxxxxxx '
Subject: [SI-LIST] Re: PCB STACKUP


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Can someone comment on the impact of assymetrical stackup on PCB yield ?

Thanks

Perry

Michael Khusid wrote:

> Alexander,
>
> Unless I miscounted, I can see 27 layers in your stackup. An odd number=
 of
> layers will get you an assymetrical stackup and will cause PCB warpage.
>
> Michael
>
> -----Original Message-----
> From: Nosovitski, Alexander (Contr)
> To: si-list@xxxxxxxxxxxxx
> Sent: 1/21/04 4:02 PM
> Subject: [SI-LIST] PCB STACKUP
>
> Hello si-list,
>
> The design I am working on has a dense placement.
>
> The proposed stack up looks as follow:
>
> TOP
> POWER_ANALOG
> DIFF_SIGNAL (Gb/s signals)
> AGND
>
> GND
> POWER
> S
> S
> GND
> POWER
> S
> S
> GND
> SPLIT_POWER
> GND
> S
> S
> POWER
> GND
> S
> S
> GND
>
> AGND
> DIFF_SIGNAL_ANALOG (Gb/s signals)
> POWER ANALOG
>
> BOTTOM
>
> All signal layers are 0.5 Oz copper and
>
> All planes are solid ( except one in the middle) with  0.5 Oz copper.
>
> The diff. signals are running at 2.5Gb/s.
>
> There are different opinions about analog plane location.
>
> Could the arrangement above cause a problem?
>
> What else should I be concern about?
>
> Any help or suggestion is appreciated!
>
> Regards,
>
> Alexander Nosovitski
>
>
>
>
>
> -----Original Message-----
> From: Salkow, Steven [mailto:steven.salkow@xxxxxxxx]
> Sent: Wednesday, January 21, 2004 1:57 PM
> To: weirsp@xxxxxxxxxx; fred@xxxxxxxxxxxxx; kar_thik_v1@xxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Looking for thin dielectric tape
>
> 4 mil prepreg (pcb laminate) is generally available from anyone doing
> multilayer PCB. You may also get samples from laminate vendors (dupont,
> Norplex) (sprayed with Scotch 444 adhesive for cold adhesion to copper
> foils)
> 3M (tape division) have exactly what your looking for up to 36" wide
> slit to any width but they have minimum qtys
>
> see
> http://products3.3m.com/catalog/us/en001/utilities_telecom/oem_electrica
> l/node_R5MTBSFVGPbe/root_GST1T4S9TCgv/vroot_GSHBRQT7DVge/gvel_BBGZX3B1QG
> gl/theme_us_oemeletrical_3_0/command_AbcPageHandler/output_html
>
> Catalog on the above page for download
>
> Steve Salkow
> Lockheed Martin
> 3200 Zanker Road
> San Jose, CA 95134
> (408) 473-4058 (san Jose)
> (408) 742-4162 (Sunnyvale)
> steven.salkow@xxxxxxxx
> salkow@xxxxxxxxxxxx
> (925) 462-1075 Home
> (925-) 487-5946 Cell
> (408) 468-7271 Numeric Pager
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of steve weir
> Sent: Tuesday, January 20, 2004 11:17 PM
> To: fred@xxxxxxxxxxxxx; kar_thik_v1@xxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Looking for thin dielectric tape
>
> If you want to lay out a board, onesy, twosy, Express PCB is not a bad
> way
> to go.  www.expresspcb.com It sure beats the Bishop Graphics adhesive
> backed Cu tape, or a bathroom full of ferric chloride.
>
> Steve.
> At 01:44 PM 1/20/2004 -0800, Fred Townsend wrote:
> >The last time I check you could still get mylar sheeting at most
> >drafting and staionary stores. You would to apply your own adhesive.
> >Comes in 4 and 7 mil thicknesses. You can also get polyester sheeting
> >frosted one side and adhesive on the other for making labels.  Failing
> >that how about 3M's double sticky magic tape?
> >
> >Fred Townsend
> >
> >Karthik V wrote:
> >
> > >Hello,
> > >
> > >         I am a student at the State University of New York. I am
> > looking for a double sided sticky dielectric tape (more like a sheet )
> of
> > thickness about 4mils (0.1mm) and with a dielectric constant of
> > around  4, to use between copper sheets - to make a "temporary board".
> I
> > tried things like epoxy, but it's almost impossible to get it so thin
> and
> > still provide infinite DC resistance.
> > >
> > >          Could anyone point me to places where I could look for this
>
> > kind of stuff. Is there anything else I could try to get the
> dielectric
> > (with Dk around 4) so thin ( apart from elaborate processes )   .
> > >
> > >thanks in advance,
> > >Karthik,
> > >
> > >---------------------------------
> > >Do you Yahoo!?
> > >Yahoo! Hotjobs: Enter the "Signing Bonus" Sweepstakes
> > >
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--
Perry Qu

Design & Qualification       |      600 March Road
Alcatel Canada               |      Ottawa, ON K2K 2E6, Canada

DID: (613) 7846720           |      FAX: (613) 5993642


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