[SI-LIST] Re: Broadside coupled line vertical registration
From: "Dunbar, Tony" <tony_dunbar@xxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Date: Thu, 5 May 2005 11:24:24 -0500
In the past, if memory serves me right, Scott McMorrow has contributed
valuable information on this topic and it should be locatable in the
archives, along with other folk's inputs on the thread. Scott may also
have a paper on this, but I'm less sure of that.
Regards,
Tony
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Bill Wurst
Sent: Thursday, May 05, 2005 10:07 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Broadside coupled line vertical registration
Mark,
While you are evaluating the effects of copper registration, don't
forget to also include the effect of manufacturing variations in the
thickness of the three dielectrics: top plane-to-trace, trace-to-trace,
and bottom plane-to-trace. Each one will have an impact, the degree of
which is dependent upon the relative spacing and the amount of variation
relative to the nominal thickness, as well as the width of the traces.
Regards,
-Bill
/************************************
/ billw@xxxxxxxxxxx /
/ /
/ Advanced Electronic Concepts, LLC /
/ www.aec-lab.com /
************************************
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Ed Sayre III wrote:
> Mark,
> Try using a free ware field solver for this. It is a simple=20
> experiment and you will surprised by the results.
> We have done some substantial investigations into this and found=20
> that the broadside registration is not as sensitive to variations as=20
> edge coupled spacing and dielectric thicknesses. Of course the issue=20
> is the level of coupling for the lines. The tighter the mutual=20
> coupling the more critical the registration. Thus try your stack and
see.
>=20
> Regards
> -Ed
>=20
>=20
>=20
>=20
> At 02:37 PM 5/5/2005 +0100, Mark Burford wrote:
>=20
>>I have an interesting query, I would like to know what you guru's=20
>>think about the effect of the vertical alignment of a broadside=20
>>coupled trace and the error it could potentially introduce to 2D field
>>solvers and the traditional transmission line approximation formulas=20
>>for calculating Z0, C and L. To clarify: a perfect alignment I am=20
>>classing as both lines exactly stacked one above the other with with=20
>>core material in the centre an no over hang, worst case would be one=20
>>line being offset to the left or right by 50 percent.
>>
>>Could the potential error introduced be described to a first order by=20
>>decreasing the capacitance by at worst case 0.5? What would be the=20
>>2nd order effects?
>>
>>Your thoughts I am sure will be as diverse as they are interesting.
>>
>>Thanks guys
>>
>>Mark Burford=3D20
>>EngD Research Engineer
>>
>>------------------------------------------------------------------
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