[SI-LIST] Re: [!! SPAM] Re: 6 layers stackup
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: "Tom Biggs" <tbiggs@xxxxxxxxxxxxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Wed, 27 Feb 2008 08:35:59 -0800
Tom,
Well put!
> [Original Message]
> From: Tom Biggs <tbiggs@xxxxxxxxxxxxxxxxxxxxx>
> To: <si-list@xxxxxxxxxxxxx>
> Date: 2/26/2008 6:16:04 PM
> Subject: [SI-LIST] Re: [!! SPAM] Re: 6 layers stackup
>
> You can take the bulldozer analogy two ways. It depends on whether you
> care about the weight of the bulldozer with passengers, or just the
> weight of the passengers.
>
> Steve's test fixture was geared toward 'weighing the passengers'. Lee's
> was toward 'weighing the bulldozer'. So they each served their purpose.
> His whole point was that the vias going down 50 mils on a board are
> going to swamp out the advantages of low inductance caps. His test
> fixture, by design, had vias that go down 50mils. I'm sure he'd agree
> that this would be a bad fixture for measuring the cap itself, which was
> not his goal.
>
> The appropriate land pattern to use for the low-inductance caps is a
> separate issue. I'd be curious to see Lee's board with Steve's land
> pattern.
>
> -tom
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Muranyi, Arpad
> Sent: Tuesday, February 26, 2008 1:31 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: [!! SPAM] Re: 6 layers stackup
>
> Can't resist to illustrate this with an example:
>
> If you want to compare the weight of an ant and a cricket and you put
> them on top of the same bulldozer, you will not see much difference in
> their weight...
>
> Arpad
> ------------------------------------------------------------------------
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Lee Ritchey
> Sent: Tuesday, February 26, 2008 11:16 AM
> To: Charles Grasso; Scott McMorrow
> Cc: Steve Weir; QU Perry; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: [!! SPAM] Re: 6 layers stackup
>
> What does the test vehicle have to do with it? Both capacitors are
> seeing
> the same stackup. It's apples and apples. Why 26 layers? Lots of
> PCBs
> have 26 layers, pretty much all of them in terabit routers. This PCB
> was used to test may things besides these two capacitors.
>
> What is being presented is the difference between the two capacitors
> under the same set of test conditions and it is not much.
>
> There are two sets of tests. One with the capacitors connected to the
> first two planes inside the PCB, which is the lowest added inductance
> and the other is with the capacitors attached to two planes further down
> in the PCB.
> ------------------------------------------------------------------
> 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: =20
> //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
> =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
>
------------------------------------------------------------------
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:
