Jim

This is a message received awhile back.

Norm

Andy Burkhardt wrote:
>
> At 10:10 15/08/97 -0400, you wrote:
> >Does anyone have a formula for calculating the distributed
> >capacitance of copper planes? I Know I have seen this before
> >in PCD magazine but I seem to have *lost* the issue.
> >
> >Thanks in advance for your assistance.
> >
> >Jeffrey McGlaughlin
> >BFGoodrich Avionics Systems Inc.
> >1105 Schrock Road
> >Suite 800
> >Columbus Ohio 43229
> >(614)825-2232 (voice)
> >(614)825-2037 (fax)
> >[log in to unmask]
> >
>
> Jeff,
>
> Not sure if this is what you're after:
>
> Capacitance of a parallel plate capacitor (or parallel copper planes)
> is given as:
>
>       C = Eo x Er x A
>           -----------
>                D
>
> Where:
>        C  = capacitance in Farads      (F)
>        Eo = permittivity of free space (8.854 x 10exp-12) (F/m)
>        Er = relative permittivity  (typically FR-4 is 4.6 at 1 MHz) (no units)
>        A  = area of the plates (or planes) (m x m)
>        D  = distance between plates (or planes) (m)
>
> This equation neglects fringing effects.
>
> Best regards
>
> Andy Burkhardt <[log in to unmask]>
> Tel: + 44 1481 53081
> Fax: + 44 1481 52476
> http://www.polar.co.uk
> ----------------------------------------------------------------------
> World leaders in PCB faultfinding and controlled impedance measurement
> ----------------------------------------------------------------------

--
> From IPC.ORG!owner-designercouncil Wed Feb 10 16:38:37 1999
> MIME-Version: 1.0
> Date:         Wed, 10 Feb 1999 17:40:17 -0500
> From: Jimmy Blier <[log in to unmask]>
> Subject:      [DC] printed capacitance
> To: [log in to unmask]
>
> Hi everyone,
>
> I need to know where I could find information on how to do and calculate a
> printed capacitor on a PCB.
> What IPC books should I be looking for, or maybe if something could be found
> on the WEB on the subject.
>
> I saw something about it a long time ago, but I forgot all about it.  Any
> help would be appreciated.
>
> Cheers,
>
> Jimmy Blier
> CAD Department. (Manager)
> P A R A D O X
> S E C U R I T Y        S Y S T E M S
> Email: [log in to unmask] <mailto:[log in to unmask]>
>
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