For some reason, this seems to be a good compromise between pcb house
capabilities and final design requirements...
Oh but wait.... which geometry should be specified...??? I believe
the specified geometry depends on the application. For instance... if
are creating a pcb that will be used as an edge card... it may be best
specify the height between the outer signal to ground height...
I know this isn't perfect... but rather a comprimise... However, as we
know many options will work... but some are more important than others
Just another reference point...
> -----Original Message-----
> From: email@example.com
> [mailto:firstname.lastname@example.org]On Behalf Of Abe Riazi
> Sent: Monday, August 16, 1999 12:43 PM
> To: 'email@example.com'
> Subject: RE: [SI-LIST] : Stackup Extraction
> Thanks for your response.
> I always pay a close attention to effects of manufacturing tolerance
> variations. SI simulations are carried out for three corners (i.e.
> fast, typ and slow), and numerous model and PCB parameters are allowed
> to vary according to tolerance requirements. For instance, the value of
> substrate dielectric constant may be 4.2 for fast, 4.4 for typical and
> 4.6 for slow corners. Similarly, substrate thickness for fast, typical
> and slow corners can be 5.2 mils, 4.5 mils, and 3.8 mils respectively.
> This is considered necessary to verify the design under all conditions.
> Experience has proven to me that "stackup extraction", which I had
> attempted to explain clearly in my communication, is important. It can
> serve to eliminate numerous SI simulation problems and enhance
> simulation accuracy.
> Best Regards,
> >From: Patrick Riffault[SMTP:firstname.lastname@example.org]
> >Sent: Monday, August 16, 1999 4:46 AM
> >To: email@example.com; 'firstname.lastname@example.org'
> >Cc: Ken Hempen; Walt Otto
> >Subject: Re: [SI-LIST] : Stackup Extraction
> >At 08:10 AM 8/15/99 -0700, Abe Riazi wrote:
> >Although obtaining an accurate representation of a stackup is
> >necessary when doing simulations I would not rely on the
> >extracted information to determine if a board passes SI.
> >I would use the ranges that were specified when the PCB
> >was designed to ensure that everything will work over all manufacturing
> >ranges (example dielectric of 4.1 to 4.7, trace width of
> >4.8 to 5.2 mils). The extracted information is only one of many
> >combinations permitted by the design.
> ><SNIPPED to save BW>
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