[SI-LIST] Re: copper thickness of a ref plane
- From: "Ken Cantrell" <Ken.Cantrell@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Tue, 4 Sep 2001 09:21:23 -0600
Jim,
Just back from vacation, so my mind isn't back in gear yet (still golfing).
I assume you are talking about edge coupled ustrip and strip lines. What
formulas are you using (in addition to simulation software)? I'm not
getting the connection between plane thickness and crosstalk as a dominant
coupling capacitance. For edge coupled ustrips there are three mutual
capacitances to account for in odd mode:
1. Cs - the mutual coupling capacitance considering the effect of er only.
2. Cso - the mutual coupling capacitance considering the effect of eo only
3. Ct - the mutual coupling capacitance due to strip thickness, considering
the effect of eo only.
Although Ct is linear with increasing thickness, the dominant capacitance,
Cso, is an order of magnitude greater than Ct. Cso is independent of trace
thickness.
For even mode, the mutual fringing capacitance is independent of thickness.
All of the above is relevant to traces, not planes.
So you can see my confusion. Can you clarify?
Thanks,
Ken
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Peterson, James F
(FL51)
Sent: Thursday, June 21, 2001 6:18 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: copper thickness of a ref plane
Michael,
the driver for moving to 1/2 oz. copper is clearance through the pin fields
of the connectors. i have to stay 12 mils away from the pads of a pci
connector on a ground plane if the plane is 1 oz. - if it's 1/2 oz., then i
only have to stay 8 mils away. this allows more copper through the pin
fields on my ref planes.
regards,
Jim
-----Original Message-----
From: Greim, Michael [mailto:mgreim@xxxxxxxxxxxx]
Sent: Wednesday, June 20, 2001 4:59 PM
To: 'si-list@xxxxxxxxxxxxx'
Subject: [SI-LIST] Re: copper thickness of a ref plane
Make sure that the ampacity of a half ounce plane
is adequate for your needs. What is driving your
decision to head in this direction? There may be
a better alternative.
Best Regards,
Michael C. Greim Sonus Networks
mgreim@xxxxxxxxxxxx 978-589-8336
Making the world safe for digital signals everywhere
And all this science I don't understand
It's just my job six days a week
The time is gone. The email's over
Thought I'd something more to say......
-----Original Message-----
From: Peterson, James F (FL51) [mailto:james.f.peterson@xxxxxxxxxxxxx]
Sent: Wednesday, June 20, 2001 4:31 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] copper thickness of a ref plane
Because of physical limitations, I am considering reducing all of the ref
planes on a design to 1/2 oz. copper (was 1 oz. copper). The board level
logic is 3.3V CMOS. Does anybody see any problems with doing this?
thanks,
Jim
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