[SI-LIST] Re: fiber-weave effect alive and well?

  • From: "Aditya Chandra" <aditya@xxxxxxxxxxxxxxx>
  • To: <m_p_sen@xxxxxxxxx>, <hreidmarkailen@xxxxxxxxx>, "si-list" <si-list@xxxxxxxxxxxxx>
  • Date: Thu, 30 Aug 2007 10:42:21 +0530

Hello

One reason I can think of is when two traces are running in paralled then 
lets say as an example at the point of 90 degrees angle or 45 degrees angle 
the distance between the tracks changes which has an effect on impedance.

They can also become acid traps.

regards
aditya
----- Original Message ----- 
From: "sengottuvel m.p." <m_p_sen@xxxxxxxxx>
To: <hreidmarkailen@xxxxxxxxx>; "si-list" <si-list@xxxxxxxxxxxxx>
Sent: Thursday, August 30, 2007 10:36 AM
Subject: [SI-LIST] Re: fiber-weave effect alive and well?


Hi all,

 Normally, we are advised to have horizontal, vertical and diagonal traces 
in PCB not any angle. Even grater than 135 degree corners in traces are 
asked to avoid. Is this due to trace boundary line smoothness issue in 
manufacturing (say aperture control) or something else?

Thanks,
Sengo



----- Original Message ----
From: agathon <hreidmarkailen@xxxxxxxxx>
To: si-list <si-list@xxxxxxxxxxxxx>
Sent: Thursday, August 30, 2007 5:30:25 AM
Subject: [SI-LIST] fiber-weave effect alive and well?


* I've reviewed DesignCon 05,07 material on fiber-weave effect.
* A 10G (802.3ap) PHY vendor claims their demo setup used FR408 (Dk/Df =
3.77/0.012) for backplane sections and a total channel of 1meter.
* FR408, as far as I know, still has the basic weave/resin construction,
though perhaps less Dk delta.


Q:
1. Huh?  What happened?  Did the PHY vendor call in the wizard kids from
Hogworts?  What is the current reality?
2. Any knowledge of Rogers4350?  Ie: a different construction?  Weave
effect?
3. Up to date publications on this?  (Besides references in the above DCon
material.)

Also, I see no mention of the weave effect on authoritative things from
802.3ap people on commsdesign or elsewhere, from 2004 on.

---


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