I think the larger problem is the too much variation in track width which
will affect not only "regular" bulk resistance, but also high frequency
resistance of the track. The latter effect is known as skin effect.

Mike Khusid


> -----Original Message-----
> From: Phil Nutting [mailto:[log in to unmask]]
> Sent: Friday, April 12, 2002 12:31 PM
> To: [log in to unmask]
> Subject: Re: [TN] Interesting question
>
>
> They may be concerned that the copper track does not add
> sufficient resistance to change the circuit function.
>
> -----Original Message-----
> From: Don Vischulis [mailto:[log in to unmask]]
> Sent: Friday, April 12, 2002 11:49 AM
> To: [log in to unmask]
> Subject: [TN] Interesting question
>
>
> Techies:
>
> I received the following email today, and it aroused my
> curiosity.  What
> reasons exist for specifying dc track resistance when minimum
> resistance is
> governed by a combination of copper weight and design width, and track
> length?  Is this a case of over zealous specification or is
> there a purpose
> behind adding another test requirement to a product with extensive
> specifications?
>
> Don Vischulis
>
> Original message:
> You may be able to help me, as I would
> like to know why - in addition to specifying
> impedance - an increasing number of PCB designers
> and PCB fabricators are also specifying DC resistance
> of PCB tracks?
>
> I have had an increasing number of clients ask
> me about series resistance being specified on
> PCB tracks, but no one seems to know why..
>
> If you are able to help with some of the reasons
> why, I would very much appreciate hearing from you.
>
>
> Kind regards
> Martyn Gaudion
> www.polarinstruments.com
>
> --------------------------------------------------------------
> -------------------
> Technet Mail List provided as a free service by IPC using
> LISTSERV 1.8d
> To unsubscribe, send a message to [log in to unmask] with
> following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt delivery of Technet send e-mail to
> [log in to unmask]: SET Technet NOMAIL
> To receive ONE mailing per day of all the posts: send e-mail
> to [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----

----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------