Re: [SI-LIST] : MECL System Design Handbook

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From: Ritchey Lee (leeritchey@earthlink.net)
Date: Tue May 15 2001 - 05:21:10 PDT


ROy,

First, right anlge bends don't represent a yield problem at PCB fabrication and
haven't since we stopped imaging with silk screen etch resists.

The real issue is that design departments often spend extra time making right
angle bends go away by "smoothing" the routed results. This extra time should
have an offsetting benefit. It doesn't.

Even worse, many companies have discarded cad systems because they cannot be
prevented from putting right angle bends in artwork. That is a real big cost
without an offsetting benefit.

Lee

Roy_Leventhal@3com.com wrote:

> Yes,
>
> Right angle bends are:
>
> A very high frequency, essentially microwave, effect. Provided you have low
> voltages. Part of the concern is a legacy of higher voltages associated with
> discrete BJTs, and before that, vacume tube RF circuits.
>
> But, I understand chamfered or radius bends give better fab yields. So, what's
> the real issue other than refining a rule of thumb?
>
> Regards,
>
> Roy
>
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