[SI-LIST] Re: Let's talk laminate induced skew

Bill,

This is traceable to the kind of weave in the glass.  Some styles are much
better than others.  The most popular choices have been 106 glass and 1080
glass, both of which have this problem.  There is at least 1 weave style
that has very little of this problem.  We documented this in my next book
which is due out in March of this year.

Lee Ritchey


> [Original Message]
> From: Loyer, Jeff <jeff.loyer@xxxxxxxxx>
> To: <bdempsey85@xxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
> Date: 1/19/2007 7:21:53 AM
> Subject: [SI-LIST] Re: Let's talk laminate induced skew
>
> Shameless plug - I'll be presenting a paper on this at DesignCon.
>
> 6-TA2: Fiber Weave Effect: Practical Impact Analysis and Mitigation
> Strategies
>
> Jeff Loyer
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Bill Dempsey
> Sent: Thursday, January 18, 2007 4:48 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Let's talk laminate induced skew
>
> Hi All,
> =20
> I've been reading a couple of these papers published on laminate induced
> skew of trace pairs.  I know that several contributors to this forum are
> the
> authors of those papers and I would like to dig into this problem a
> little
> bit more.
> I am getting ready to build a backplane for a customer that has 40" of
> trace
> and mulitple pairs running between two connectors.  They would like to
> reach
> 6.5Gbps on these traces but when I look at some of these published
> figures
> for just p-to-n skew I am worried about being able to have a reasonable
> eye
> opening at the receiver (without EQ or pre-emphasis).
> =20
> Can I take a poll from the community and ask who else has measured data
> for
> laminate skew? What did you see?
> How many people out there are running 40" or more at greater than 3.125
> Gbps
> using FR4 (or similar material) with success?  Did you compensate for
> laminate skew?
>
> Lastly, how much does a Rogers 4350 dielectric exhibit this tendency?
> =20
> Thanks,
> Bill
>
>
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