[SI-LIST] Re: Ground Pour in Signal Layers
- From: "Gerry Gagnon" <mrgagman@xxxxxxxxxxx>
- To: CurtM@xxxxxxxxxxx, rsefton@xxxxxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Tue, 28 Feb 2006 23:52:25 +0000
I'll reply to Curt but I meant to reply to all.
Let me be specific what I was referring to with regard to my postback to
Rob.
I used the term, autotheiving, which was/is NOT copper pouring! It refers to
"post route" automation tools we used, which placed small copper squares on
alternating grid points on all signal layers everywhere there was room to do
so, subject to SI constraints on spacing in the X, Y, (and Z axes for
non-striplines). There were spaces between the squares, not continuous
copper as in a pour.
This methodology worked much better than copper pouring (which we tried) and
did not perturb signals electrically.
The only pain in the neck was the length of time to do all the spacing
checks......
Gerry
----Original Message Follows----
From: "Curt McNamara" <CurtM@xxxxxxxxxxx>
Reply-To: CurtM@xxxxxxxxxxx
To: <rsefton@xxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
Subject: [SI-LIST] Re: Ground Pour in Signal Layers
Date: Tue, 28 Feb 2006 14:47:00 -0600
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FILETIME=[D25B1B40:01C63CAE]
So the signal integrity aspect:
Either do it yourself so you know where it is.=20
Or --
Place a requirement on the fab drawing that requires approval of the
engineer. This is risky because sometimes the fab vendor will call your
layout department and the answer might not be what you would have said!
There is another perspective as well: thieving can destroy a clearance
and result in losing a safety approval. So it really is best to have
your layout team do it.
Overall it makes sense -- if you don't have to etch that copper away
then process times should decrease, yields should go up and life should
be better :-) None of this is huge, but all of our little efforts add
up!
Curt
Curt McNamara. P.E.=20
Senior Electrical Engineer=20
Logic Product Development=20
411 Washington Ave. N Suite 101=20
Minneapolis, MN 55401=20
Tel 612-436-5178=20
Fax 612-672-0443=20
curtm@xxxxxxxxxxx=20
www.logicpd.com=20
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Robert Sefton
Sent: Tuesday, February 28, 2006 1:02 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Ground Pour in Signal Layers
Search the TechNet archives. Thieving comes up quite a bit. I'd say the
consensus is that thieving on inner layers is important to help bonding.
Some also claim it can help reduce warpage. On outer layers it's to
achieve more uniform plating.
http://listserv.ipc.org/archives/technet.html
Bob S.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Lee Ritchey
Sent: Tuesday, February 28, 2006 10:08 AM
To: Charles Grasso; Gerry Gagnon; rhaller@xxxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Ground Pour in Signal Layers
Might want to check with the process engineers at Merix or TTM on this
one.
> [Original Message]
> From: Grasso, Charles <Charles.Grasso@xxxxxxxxxxxx>
> To: <leeritchey@xxxxxxxxxxxxx>; Gerry Gagnon <mrgagman@xxxxxxxxxxx>;
<rhaller@xxxxxxxxxxxxx>
> Cc: <si-list@xxxxxxxxxxxxx>
> Date: 2/28/2006 9:34:58 AM
> Subject: RE: [SI-LIST] Re: Ground Pour in Signal Layers
>
> How interesting! I have not had to deal with thieving on inner layers
> so I popped down to our layout group and asked our folks there. The=20
> consensus was - YES - Thieving on inner layers can be necessary and=20
> should be used for unbalanced layouts. Indeed one former employee of=20
> DDI indicated that DDI had a program that automatically added thieving
> based on the design. The reason for adding the thieving is to avoid=20
> warpage.
>
>
> Best Regards
> Charles Grasso
> Senior Compliance Engineer
> Echostar Communications Corp.
> Tel: 303-706-5467
> Fax: 303-799-6222
> Cell: 303-204-2974
> Pager/Short Message: 3032042974@xxxxxxxx
> Email: charles.grasso@xxxxxxxxxxxx;
> Email Alternate: chasgrasso@xxxxxxxx
>
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