[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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