[SI-LIST] Re: Dust and humidity impact on the signal
- From: Scott McMorrow <scott@xxxxxxxxxxxxx>
- To: Fabrizio.Zanella@xxxxxxx
- Date: Wed, 17 Jan 2007 12:38:37 -0500
To follow up, accommodation of the impact of humidity on Er and loss
tangent should be fairly easy, although I've not tried it.
1) Dry out your target material in an autoclave
2) Weigh it.
3) Place the material in a humidity chamber
4) Weigh it.
5) Compute the percentage water by weight.
6) Compute the average increase in Er and loss tangent by using the
ratios of dielectric and absorbed water.
Once you know these, it should be possible to create a lossy dielectric
model that is a pretty close match for 2D or 3D solvers. For extra
credit, actual material measurements could be made using one of the many
methods know for Er and TanD extraction, at multiple frequency points,
to create a more precise frequency dependent model. However, I think if
you perform steps 1 to 6 above you'll be closer than you might imagine
(assuming that you know your original material properties well.
I wouldn't worry much about dust, except for microstrip. In that case,
I guess one could make some TDR measurements with and without dust and
see what happens. (It's not like it's hard to create some good dust ...
just get yourself a good circular saw, create some fine dust, and
sprinkle it over the trace.
Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax
http://www.teraspeed.com
Teraspeed® is the registered service mark of
Teraspeed Consulting Group LLC
Fabrizio.Zanella@xxxxxxx wrote:
> Dorin, there's a good paper from DesignCon 2004 which has information on
> measurements on serial links including the effect of temperature and
> humidity=2E
> 'The Impact of Environmental Conditions on Channel Performance', by Greg
> Sheets, Agere and John D'Ambrosia, Tyco=2E You can take the dk
> information and apply it as a variable in a 3D simulator, and then use a
> parametric sweep=2E
>
> I can send you this paper if you're interested=2E
>
> Regards,
>
> Fabrizio Zanella
>
>
> -----Original Message-----
> From: Dorin=2EOprea@alcatel-lucent=2Ecom
> [mailto:Dorin=2EOprea@alcatel-lucent=2Ecom]
> Sent: Wednesday, January 17, 2007 10:59 AM
> To: si-list@freelists=2Eorg
> Subject: [SI-LIST] Dust and humidity impact on the signal
>
> Hi,
>
> I try to simulate the dust and humidity impact on 10G differential
> signal routed as micro strip on the board=2E I know that the dust
> thickness and humidity can vary significantly, but I wonder what would
> be a good approach, for start, to build the corresponding model in a 3D
> simulation tool (suggestions on dk, df)=2E
>
> Thanks,
> Dorin
>
>
>
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