Lenght of the stub can be really critical, drill too deep and your circuit
is toast, don't drill deep enough and your circuit is not optimized.
I did a lot of work on absolute z axis drill depth to ensure drill stop at
target layer every time, and it was not an easy concept, since you cannot
"measure things" and the position of the target player changes slightly from
board to board.
John
------------------------------------
Avanex
John Burke
Senior Manager RoHS Compliance
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------------------------------------
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Dave Seymour
Sent: Wednesday, June 08, 2005 7:26 AM
To: [log in to unmask]
Subject: Re: [TN] stubbing in circuit design?
Ken,
When designing a PCB, the engineers talk about "Stubs" as a "T" in the
signal route.
o------------o------------o This is daisy chain.
o------------o-----------o
|
|
|
o This is a "Stub" or "T".
Depending on the frequency ( rising edge) of the signal, reflections could
create false triggering of the circuit.
Stubs are impossible to design out 100%, think about pin escapes, or
wire bonds
on the IC itself. However, the length of the stub is can be critical.
Do some google searches on signal integrity or high speed design.
Hope this helps,
Dave
Dave Simonik wrote:
>Could this be referencing the plated hole wall remaining above the Must Not
>Cut (MNC) layer after Back Drilling on back planes? This is normally
>referred to as the 'Stub'.
>
>Dave Simonik
>Sanmina SCI
>Owego NY Division
>
>-----Original Message-----
>From: Kanaiyalal Patel [mailto:[log in to unmask]]
>Sent: Wednesday, June 08, 2005 9:54 AM
>To: [log in to unmask]
>Subject: stubbing in circuit design?
>
>
>All,
>What is stubbing in PCB circuit design? Can some one
>send me a picture or link to visulize it?
>
>Re,
>Ken Patel
>
>
>
--
Dave Seymour, CID+
Catapult Communications Inc.
800 Perimeter Park Dr, Suite A
Morrisville, NC 27560
Direct: (919)653-4249
Main: (919)653-4180
Fax: (919)653-4297
[log in to unmask]
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