You should question their reasons! If you have lots of things (IC's &
connectors) which connect to all 3 planes (shorting them together with a
via), you have effectively made one plane. Although the ground currents do
not share (among the 3 planes) equally, the sharing will be hard to
predict. And there will certainly be some 'filter current' on each of the
2 outer planes.
Or, have I misunderstood what you do?
At 04:45 PM 6/15/2001 Friday, you wrote:
>Mike,
>
>Based on customer requirements I need 3 ground planes.
>
>They all share the same net name however (as they must):
>
>The IC's and connectors, etc. hit all three planes
>Filter Caps only connect to the inner most ground plane
>and any signal that must pass through the "core power/ground" pair
>must have a return ground via that only connects to the 2 outer most
>ground planes.
>
>By Manipulating the plane clearences by say a mil I get a separate Dcode
>for the desired pads and can modify the gerbers to thermals where
>required.
>
>I have been meeting these requirements for many years and their boards
>always work so who am I to question their reasons.
>
>Regards,
>
>Jim McGrath
>CAD Connections, Inc.
>
>
>Michael Reagan wrote:
>
> > > > I recall you once emailing me with some details of a PCB that you had
> > > > designed, in which you wanted various pads to connect to different
> Power
> > > > Plane layers in different ways (Direct Connect, Thermal Relief
> > > Connect, or
> > > > No Connect). Although I didn't respond to you soon afterwards, I did
> > > > eventually send you a response in which I suggested that you
> > > could specify
> > > > the pads concerned to Direct Connect to the Power Plane layers,
> > > and then add
> > > > primitives (arcs or single layer pads) to each Power Plane layer as
> > > > appropriate to effectively change each connection between each
> > > pad and each
> > > > Power Plane layer to whatever you required (i.e. Thermal Relief
> > > Connect or
> > > > No Connect).
> >
> > Jim
> > Why would you want to do this? if I may ask
> >
> > Mike Reagan
> > EDSI
> > Frederick Md
> >
Cheesecote Mountain CAMAC
24 Halley Drive; Pomona, NY 10970
845 364 0211, www.cmcamac.com
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/subscrib.html
* - or email -
* mailto:[EMAIL PROTECTED]?body=leave%20proteledaforum
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Browse or Search previous postings:
* http://www.mail-archive.com/[email protected]
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
