[SI-LIST] Re: DesignCon presentations posted

  • From: Istvan Novak <istvan.novak@xxxxxxx>
  • To: Bill Dempsey <cadcocat@xxxxxxxxx>
  • Date: Wed, 17 Feb 2010 00:58:36 -0500


Valid questions, but I am afraid at this point I have to stay vague. I 
think it is fair
to say that these questions pose significant challenges to many of us in 
this industry.


Bill Dempsey wrote:
> Istvan,
> Ok, still absorbing a lot of great papers here... and
> while doing so I seemed to have missed this one:
> http://www.simberian.com/AppNotes/DesignCon2010_Paper2807.pdf 
> which elaborates a method "similar" to what I proposed.  I use the word 
> "similar" very loosely here. :)
> In
> that paper, the authors state "Conductor resistivity and RMS
> measurements of roughness and roughness factor make it possible to
> separate all metal losses with high confidence – it is impossible to
> identify the dielectric properties without such separation in the
> model"Â  You seem to indicate that this might be an issue (re:
> cross-correlation).
> So what do you (read:Sun) do with regards to
> Dk/Df frequency dependence?    What about everyone else out there? 
> What's next?  Seems like Simbeor is addressing this in their tools --
> anyone else?
> ...thinking...
> Bill
> --- On Tue, 2/16/10, Istvan Novak <istvan.novak@xxxxxxx> wrote:
> From: Istvan Novak <istvan.novak@xxxxxxx>
> Subject: Re: [SI-LIST] Re: DesignCon presentations posted
> To: "Bill Dempsey" <cadcocat@xxxxxxxxx>
> Cc: si-list@xxxxxxxxxxxxx, Istvan.Novak@xxxxxxx
> Date: Tuesday, February 16, 2010, 10:02 PM
> Hi Bill,
> Yes, all those things you mention are doable, but the challenge is that 
> eventually we need a trusted model to fit to, because beyond a few hundred 
> MHz there is no direct way to measure the contributing factors separately. 
> AND the more cross-correlation we do (for instance different line trace 
> length, different line widths, etc) the more we rely on the elusive 
> assumption that everything else stays the same except the single
>  parameter we intend to change.
> Regards,
> Istvan Novak
> Oracle-SUN
> Bill Dempsey wrote:
>> <second posting...apologies>
>> Hi Istvan,
>> I just read the DesignCon paper on the loss tangent measurement and had a 
>> question with regards to other possible techniques to measure Df (and 
>> similarly Dk).
>> Previously you built a stripline test board for measuring glass weave 
>> effect.  The cool thing about this board was that you launched from 
>> "inside" the board and minimized the effects of the launch structure.   
>> Couldn't you build a similar test board with various copper line widths and 
>> measure insertion loss on a VNA?  Once you have the insertion loss, 
>> couldn't you then subtract out the Rdc+Rac component from the overall 
>> insertion loss to give you a loss curve from which you could derive Df?  
>> Use the various line widths to minimize any weave effect.
>> Using this same
>  board, can you not look at group delay to also measure the Dk over frequency?
>> I know your paper talks about cured and uncured resin variations but in the 
>> end, isn't it just the cured value we need?  Most tools don't address a 
>> frequency dependent Df/Dk at this time so what do we do once we get a 
>> frequency dependent Dk/Df anyway? I'm curious to see how others are 
>> addressing this issue and how much their lab measurements have been off from 
>> simulations.
>> And I'd like to see some posts from tool vendors who are addressing the 
>> frequency dependence of these values.
>> Regards,
>> Bill
>> From: istvan Novak <Istvan.Novak@xxxxxxx>
>> To: SI-List
>> Â  <si-list@xxxxxxxxxxxxx>
>> Sent: Mon,
>  February 15, 2010 10:52:42 PM
>> Subject: [SI-LIST] DesignCon presentations posted
>> FYI:
>> For those of you who could not make it to DesignCon, the Oracle-SUN 
>> presentations are posted at http://www.electrical-integrity.com/
>> For the three Best Paper Award winner presentations, both the written 
>> materials and the slides are posted:
>> “Introduction and Comparison of an Alternate Methodology for Measuring 
>> Loss Tangent of PCB Laminates�
>> “Additional Trace Losses due to Glass-Weave Periodic Loading�
>> “Accuracy Improvements of PDN Impedance Measurements in the Low to 
>> Middle Frequency Range�
>> Also posted are the slides for the panel discussion "Making Sense out of 
>> Dielectric Loss Numbers, Specifications and Test Methods"
>> Regards,
>> Istvan Novak
>> Oracle-SUN
>> Â Â Â 

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