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Steve,
I understand much work was done, as I should caution there are a
number of patents for this process out there. It is a good idea, it
does work, but please notify your intellectual properties department
and / or your polymer supplier prior to implementation. Some suppliers
are working on or have completed licensing agreements.
Regards,
Allen Hertz
Racal-Datacom
(945) 846-5829
______________________________ Reply Separator _________________________________
Subject: Re: Internal and external ground planes
Author: [log in to unmask] at ftl03
Date: 10/23/96 3:55 PM
Is anyone out there investigating or using a conductive Polymer Thick
Film layer on the outside of the board to reduce EMI. Using this PTF
allows you to possibly go from a 4 layer board with internal ground
planes to a 2 layer board. CHEAPER!!!!!!!!
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: Re: Internal and external ground planes
Author: Non-HP-dwalker ([log in to unmask]) at HP-Vancouver,shargw2
Date: 10/23/96 8:38 AM
I believe you should tie the external ground plane at one point only.
The return current path often completes a loop antenna - a highly directional
radiation source - and if, by connecting the components to the outer shield,
you make the outer plane a part of the current return path you have turned
your shield into a radiation source.
Don Walker
[log in to unmask]
> We design high speed line scan cameras and use internal and
> external ground planes (external for shielding) on our PCB's.
> My question is this-
>
> Should the internal and external planes be tied throughout the board (at
> vias, etc.) or should the external planes be tied back only at a single
> soure (power connector) and leave the internal plane(s) for all component
> connections? I am wondering if there are advantages of one over the other.
>
> VIP Lab
> University of Arkansas
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