From: Muhammad S. Sagarwala ([email protected])
Date: Wed Nov 01 2000 - 08:30:34 PST
No the via size did not change at all...
As for your second question...I checked all the power and ground connections
on the caps and they seem to be O.K.
I also looked at the gerbers to see if anything is different but nothing
stood up...
Muhammad
-----Original Message-----
From: Bill Owsley <[email protected]>
To: Muhammad S. Sagarwala <[email protected]>; Zabinski, Patrick
J. <[email protected]>; [email protected]
<[email protected]>
Date: Wednesday, November 01, 2000 7:52 AM
Subject: Re: [SI-LIST] : effect of trace width on the performance
>copper on the power planes and the current (power) level seems like a good
>start.
>ps. did the via size change ? did you track the power/ground into the pins
>from vias attached to caps ?
>
>At 07:04 PM 10/31/2000 -0800, Muhammad S. Sagarwala wrote:
>>Patrick,
>>
>>The lines are single ended but the spacing betweent them is 2x, 3x or
>>4x.(2x or greater) so
>>I do not think cross talk is an issue.
>>
>>The edge rates on the boards are exactly the same.
>>
>>
>>
>>The problem I feel is because of "ground bounce"...I was wondering if the
>>trace width and copper on power planes play a major
>>part ?????
>>
>>Muhammad
>>-----Original Message-----
>>From: Zabinski, Patrick J. <[email protected]>
>>To: [email protected] <[email protected]>;
>>[email protected] <[email protected]>
>>Date: Tuesday, October 31, 2000 6:54 PM
>>Subject: RE: [SI-LIST] : effect of trace width on the performance
>>
>>
>> >Muhammad,
>> >
>> >This alone would make me think the 7.5 mil wide trace board would
>> >work better than the 9 mil wide trace board due to the lower crosstalk.
>> >This assumes single-ended lines, but the opposite would be true
>> >for differential lines. Are the lines differential or single ended?
>> >
>> >If this isn't it, my next best guess is the attenuation of the lines.
>> >With cyanate ester, the loss tangent is quite low (around 0.001 if I
>> >recall??), so I don't think you'll be running into much dielectric
>> >loss at 400 MHz. However, the wider/thicker traces will have much
>> >less loss at both DC and higher freqs than the narrower/thinner
>> >traces (at least a factor of two better).
>> >
>> >Have you looked at the signal degradation differences between the
>> >two boards? Are the edge rates on the two board different?
>> >
>> >If this isn't it, then I'm clueless.
>> >
>> >Pat
>> >
>> >>
>> >> Exactly the same...
>> >>
>> >>
>> >> >How about center-to-center pitch on routing tracks?
>> >> >
>> >> >>
>> >> >>
>> >> >> I am sorry Patrick,
>> >> >>
>> >> >> I forgot to mention ... the thickness of the boards is
>> >> >> different. The one
>> >> >> with 9 mil wide traces is thicker than the one
>> >> >> with 7.5 mil wide traces.
>> >> >>
>> >> >> As regards other possibilities, the boards use the same
>> >> >> dielectric material
>> >> >> (Cynate Ester), the power planes on them
>> >> >> are exactly the same, and the stackup is the same too and the
>> >> >> placement of
>> >> >> the decoupling caps is pretty much the same too
>> >> >> (both the physical location and quantity)..
>> >> >>
>> >> >> Muhammad
>> >>
>> >
>>
>>
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>
>----------------------------
>Bill Owsley, [email protected]
>919) 392-8341
>
>TMBU Compliance
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>
>
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