Scott listed my preferred weave styles in another reply. And, yes we do very
well when we control the weave type. Better than any of the other methods that
have been proposed.
Just had a PCB with 200+ 10 Gb/S paths with the worst skew being 2 pSEC.
-----Original Message-----
From: Istvan Nagy [mailto:buenoshun@xxxxxxxxx]
Sent: Wednesday, December 30, 2015 1:35 PM
To: SI <si-list@xxxxxxxxxxxxx>; bbakshan@xxxxxxxxx; Lee Ritchey
<leeritchey@xxxxxxxxxxxxx>
Subject: RE: [SI-LIST] Re: Glass Weave effects and Cross sectioning
Lee,
What is on your list of good enough weaves? Are those provide much better
results than 2116? The nicer weaves are not as available as 2116, i am talking
about series production of networking and computing boards, not test boards.
Do you expect the skew problem to be resolved mainly by glass style selection?
Regards, Istvan, mobile
*** Sent from my BLU smartphone device *** On Dec 30, 2015 9:07 AM, Lee Ritchey
<leeritchey@xxxxxxxxxxxxx> wrote:
I have had severe skew problems with 2116 at 10 Gb/S. It is not on
my list of good weaves.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Istvan Nagy
Sent: Monday, December 28, 2015 10:53 PM
To: bbakshan@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Glass Weave effects and Cross sectioning
Hello,
First getting on this topic of spread glass, everyone is looking for
the miracle spread that has no skew issues.
You can choose the glass style as a number, or to take it further and
choose a material manufacturer who promises mechanical spread or
square wave or other features too.
In reality the traditional glass styles (106, 1080) were kind of
"bad", newer more denser weaves (2116, 1501) are "better", but there
is no "excellent" fabric.
I just try to use 2116 for layers with 2Gig+ signals. So you specify
glass style, and material name, that's mainly what you can do about
it, before building the stackup for design and manufacturing.
You need to have the detailed datasheets listing all available glass
styles of your chosen material. Get glass fabric photos from your
material vendor (like Bill from NanYa), so you can see how much
difference those different fabrics (numbers) have in covered/uncovered
areas. The board area consists of "no glass", "1-layer glass",
"2-layer glass" parts. If you imagine a simple cloth fabric, you would
know what I mean. The best material has the smallest percentage of "no
glass" area and the largest percentage of "2-layer glass" area, that would be
the most uniform (logically thinking).
"If not, how can I guarantee that the right type of weave was indeed
selected when building my board?"
- instead of "they" building your stackup and board, you have to
determine the stackup before they manufacture it. If you just let fabs
and who knows who manufacture whatever for your board designs, then
many things can go wrong.
Regards,
Istvan Nagy
-----Original Message-----
From: Boris Bakshan
Sent: Sunday, December 27, 2015 10:16 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Glass Weave effects and Cross sectioning
Hi experts,
I've been reading much on glass weave effects and its contribution on skew.
If I encounter a skew problem, can I say anything on weave type ,whether it
is mechanically spread or not by doing a cross section of my traces?
If not, how can I guarantee that the right type of weave was indeed selected
when building my board?
Thank you all!
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