[PCB_FORUM] Re: high speed board material.
- From: "Ooi, Ching Leong" <ching.leong.ooi@xxxxxxxxx>
- To: <icu-pcb-forum@xxxxxxxxxxxxx>
- Date: Mon, 21 Feb 2005 16:54:21 +0800
FR4 should be still ok, but if you are really worry about lossy and skin
depth problem on critical traces, (on external layer only) try Gold
plate it and leave the soldermask exposed on traces in question. Pls
don't ask me why, I was adviced by someone some place I worked before,
because I was asked to create a selective Au Plate layer , and special
mask opening for the traces and same advice also, "don't ask why" ,yeah,
make sure the Au not on your solder pad, makes the joint brittle, but if
you are really into RF stuff, try check out Rogers or Nelco, but $$$ can
be more..
will be really thankful if any expert out there can help answer the
"don't ask why"
..cheers
own opinion , not Intel,,
CL,Ooi
-----Original Message-----
From: Jonathan Friedman [mailto:jf@xxxxxxxxxxx]
Sent: Monday, February 21, 2005 8:25 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: high speed board material.
> (Sorry this isn't really Cadence related - does anybody mind?)
I wouldn't think so. It's interesting and useful. That is to say, that
*I*
don't mind <grin>. I can't speak for the group.
Cheers!
-Jonathan
Jonathan Friedman, GSR
Networked Embedded Systems Laboratory (NESL)
University of California, Los Angeles (UCLA)
-----Original Message-----
From: richard moffat [mailto:richard.moffat@xxxxxxxxxxxxxxxxxxx]
Sent: Sunday, February 20, 2005 12:03 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: high speed board material.
PS - we still use FR4, but I don't see this as much use above 5GHz. OK,
maybe 5 at a stretch, but certainly not 10!
Another thing we are starting to look at is the weave in FR4. This can
really mess with the impedance for fine lines.
Richard
>>> richard.moffat@xxxxxxxxxxxxxxxxxxx 21/02/2005 8:52:42 a.m. >>>
Hi
Yeah, similar - we run up to 3.125GHz at the moment. The biggest
thing
we have to worry about is loss and skin effect.
Are you sure the edge rate is 9ns? That's huge. For PCI it probably
should be ~ 200-300 ps or so, at a guess, depending on the chip
technology.
Cadence put out GHz simulation tools, but they are expensive.
Cheers,
Richard
>>> austin@xxxxxxxxxxxx 19/02/2005 11:49:32 a.m. >>>
Hi,
FR-4 is fine for your specs below. I have FR-4 boards that run
Infiniband
4x (2.5GHz x 4 signal lanes), and no problem. That's the highest I've
gone
on FR-4. I do suggest you do simulation though, and you pay careful
attention to routing rules.
BTW, 1GHz better have better than a 9ns edge rate, or you won't get
any
signal ;-)
Austin
> -----Original Message-----
> From: sjcharles@xxxxxxx [mailto:sjcharles@xxxxxxx]
> Sent: Friday, February 18, 2005 11:37 AM
> To: icu-pcb-forum@xxxxxxxxxxxxx
> Subject: [PCB_FORUM] Re: high speed board material.
>
>
> speed 1 ghz, 8 ly, 1/2 oz, rate edge approx 9n, 5/5 width and
> spacing maybe 4
> for necking. two or threes pair controlled Z. If Fr4 will do the
> job then i that
> would be fine.
>
> thanks
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