OOPS.... you are rigth for PCB traces where the lines are wide.. the
over-etching should not be a problem..... BUT From a module perspective,
where the line width can be at 20um wide, the a 90 degree bend may reduce
the substrate yield because you may neck down the line width into the
corner and consequently does not meet the design spec. Also from a
reliability point of view, this neck down will be a weak point.
Jean Audet
Electrical Analysis
World Wide Packaging & Test
IBM Burlington
Tel: 802-769-0835, tie line: 446-0835
Tel: 450-534-6317, tie line: 552-6317
E-mail: jaudet@xxxxxxxxxx
"Lee Ritchey"
<leeritchey@earth To: "Andrew Ingraham"
<a.ingraham@xxxxxxxx>, si-list@xxxxxxxxxxxxx
link.net> cc:
Sent by: Subject: [SI-LIST] Re: 90
degree bend
si-list-bounce@fr
eelists.org
08/30/2004 12:40
PM
Please respond to
leeritchey
This is another of those statements that are not true and should not be
repeated. Where did this one start?
I use right angle bends in every signal, or rather, I allow them, even 2.4
GB/S.
How long will it take to get the misinformation purged from our profession?
Lee W. Ritchey
Speeding Edge
P. O. Box 2194
Glen Ellen, CA 95442
Phone- 707-568-3983
FAX- 707-568-3504
I just used the energy it took to be angry to write some blues.
Count Basie
> [Original Message]
> From: Andrew Ingraham <a.ingraham@xxxxxxxx>
> To: <si-list@xxxxxxxxxxxxx>
> Date: 8/30/2004 9:13:51 AM
> Subject: [SI-LIST] Re: 90 degree bend
>
> The other problem is that right-angle bends tend to concentrate etchant
and
> may result in over-etching the trace a bit in the corner. Presumably it
can
> lead to a break in the trace.
>
> For most of us, that's the reason why we don't use right-angle corners.
The
> electrical effects become noticeable if you're doing multi-GHz boards.
>
> Regards,
> Andy
>
>
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