[SI-LIST] Re: matching within 1 mil
- From: "Gisin, Franz" <franz.gisin@xxxxxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Fri, 1 Jun 2007 11:50:32 -0700
It=20is=20worth=20noting=20that=20the=20anistropic=20nature=20of=20most=20=
glass-weave
reinforced=20dielectrics=20usually=20creates=20a=20lot=20more=20uncontroll=
ed=20skew
variation=20than=20what=20you=20will=20ever=20see=20from=20a=201=20mil=20v=
ariation=20in=20actual
routing=20length.
It=20is=20also=20worth=20noting=20that=20in=20most=20PCBs,=20via=20lengths=
=20-=20and=20variations
in=20via=20lengths,=20especially=20in=20thick=20PCBs=20and=20mid/back=20pl=
anes=20-=20can=20also
be=20much=20greater=20than=201=20mil.
Franz=20Gisin
Director
=20Backplane=20Design=20Technology
=20Signal=20Integrity=20Design
Sanmina-SCI
2121=20O'Toole=20Avenue
San=20Jose,=20CA=2095131
franz.gisin@xxxxxxxxxxxxxxx=20
-----Original=20Message-----
From:=20si-list-bounce@xxxxxxxxxxxxx=20[mailto:si-list-bounce@xxxxxxxxxxxx=
g]
On=20Behalf=20Of=20Loyer,=20Jeff
Sent:=20Friday,=20June=2001,=202007=207:41=20AM
To:=20si-list@xxxxxxxxxxxxx
Subject:=20[SI-LIST]=20matching=20within=201=20mil
I=20think=20folks=20are=20missing=20Bill's=20point.=20=20I=20don't=20think=
=20he's=20saying=20that
the=20design=20is=20going=20to=20break=20at=202=20mils=20routing=20differe=
nce,=20only=20that=20he
can=20easily=20attain=20a=20maximum=201=20mil=20delta,=20so=20he=20uses=20=
that=20as=20his
constraint.=20=20If=20his=20CAD=20folks=20balked=20at=20that=20number,=20h=
e'd=20probably
adjust=20accordingly=20and,=20if=20it=20got=20close=20to=20having=20signif=
icant=20impact,
would=20do=20a=20more=20detailed=20analysis.
This=20is=20very=20similar=20to=20what=20we've=20done=20for=20common-clock=
=20FSB=20signals:
tell=20our=20CAD=20folks=20to=20match=20them=20within=2010=20mils=20(or=20=
some=20number),=20even
though=20we=20know=20we=20can=20absorb=20more.=20=20But,=2010=20mils=20is=20=
easily=20attainable,
and=20guarantees=20essentially=20no=20skew=20due=20to=20length=20differenc=
es.=20=20Granted,
it's=20a=20little=20more=20work=20on=20CAD's=20part,=20but=20the=20tradeof=
f=20is=20I=20don't=20have
to=20do=20a=20grand=20analysis=20to=20figure=20out=20exactly=20how=20close=
=20they=20HAVE=20to=20be
matched,=20and=20then=20worry=20about=20whether=20my=20analysis=20was=20co=
rrect=20(and
require=20subsequent=20validation=20in=20the=20lab,=20etc.).=3D20
This=20is=20about=20compromises,=20and=20where=20you=20put=20your=20energy=
=20into=20in-depth
analysis.=20=20If=20you=20can=20easily=20do=201=20mil=20spacing,=20no=20pr=
oblem.=20=20It's=20a
little=20tighter=20than=20I'd=20generally=20specify,=20but=20it's=20not=20=
absurd,=20either.
If=20you're=20using=20an=20auto-router=20(that's=20surprising=20to=20me,=20=
I=20didn't=20think
leading-edge=20designs=20could=20use=20them),=20you=20probably=20have=20di=
fferent
constraints.
Jeff=20Loyer
------------------------------------------------------------------
To=20unsubscribe=20from=20si-list:
si-list-request@xxxxxxxxxxxxx=20with=20'unsubscribe'=20in=20the=20Subject=20=
field
or=20to=20administer=20your=20membership=20from=20a=20web=20page,=20go=20t=
o:
//www.freelists.org/webpage/si-list
For=20help:
si-list-request@xxxxxxxxxxxxx=20with=20'help'=20in=20the=20Subject=20field=
List=20technical=20documents=20are=20available=20at:
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20http://www.si-list.net
List=20archives=20are=20viewable=20at:=20=20=20=20=20
=09=09//www.freelists.org/archives/si-list
or=20at=20our=20remote=20archives:
=09=09http://groups.yahoo.com/group/si-list/messages
Old=20(prior=20to=20June=206,=202001)=20list=20archives=20are=20viewable=20=
at:
=20=09=09http://www.qsl.net/wb6tpu
=20=20
CONFIDENTIALITY
This=20e-mail=20message=20and=20any=20attachments=20thereto,=20is=20intend=
ed=20only=20for=20use=20by=20the=20addressee(s)=20named=20herein=20and=20m=
ay=20contain=20legally=20privileged=20and/or=20confidential=20information.=
=20If=20you=20are=20not=20the=20intended=20recipient=20of=20this=20e-mail=20=
message,=20you=20are=20hereby=20notified=20that=20any=20dissemination,=20d=
istribution=20or=20copying=20of=20this=20e-mail=20message,=20and=20any=20a=
ttachments=20thereto,=20is=20strictly=20prohibited.=20=20If=20you=20have=20=
received=20this=20e-mail=20message=20in=20error,=20please=20immediately=20=
notify=20the=20sender=20and=20permanently=20delete=20the=20original=20and=20=
any=20copies=20of=20this=20email=20and=20any=20prints=20thereof.
ABSENT=20AN=20EXPRESS=20STATEMENT=20TO=20THE=20CONTRARY=20HEREINABOVE,=20T=
HIS=20E-MAIL=20IS=20NOT=20INTENDED=20AS=20A=20SUBSTITUTE=20FOR=20A=20WRITI=
NG.=20=20Notwithstanding=20the=20Uniform=20Electronic=20Transactions=20Act=
=20or=20the=20applicability=20of=20any=20other=20law=20of=20similar=20subs=
tance=20and=20effect,=20absent=20an=20express=20statement=20to=20the=20con=
trary=20hereinabove,=20this=20e-mail=20message=20its=20contents,=20and=20a=
ny=20attachments=20hereto=20are=20not=20intended=20to=20represent=20an=20o=
ffer=20or=20acceptance=20to=20enter=20into=20a=20contract=20and=20are=20no=
t=20otherwise=20intended=20to=20bind=20the=20sender,=20Sanmina-SCI=20Corpo=
ration=20(or=20any=20of=20its=20subsidiaries),=20or=20any=20other=20person=
=20or=20entity.
__________________________________________________________________________=
___
Scanned=20by=20Sanmina-SCI=20eShield=20=20________________________________=
_____________________________________________
------------------------------------------------------------------
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 technical documents are available at:
http://www.si-list.net
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:
