Who's using autorouters for their designs?

I'm wondering how many people are using autorouters for their board layouts and in what percentage (i.e. what percentage is being routed by the autorouter)? I've had some bad experience using autorouters and hardly use them anymore. OTOH, Electra claims that autorouters do a very decent job with digital circuits and that even though the layout doesn't look as 'artistic' as one done by a human, they are ussually better.

When I look at board layouts on most digital products (e.g. motherboards) it seems to me that they've been done manually (i.e. most signal busses are perfectly routed next to each other, something an autorouter won't ussually do).

What do you guys think?

Reply to
Henk Boonsma
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What sort of boards are you interested in?

For really simple boards, an autorouter is fine since the routing is generally obvious, at least if you put the components in sensible places.

For really complicated boards, you don't have enough time to do it all by hand. For some sections, the routing is simple if you get the components placed right. For other sections, you have to check carefully to make sure the autorouter did something sensible, perhaps tweaking the rules and letting it try again.

For almost easy boards, I've had reasonable luck with guiding Eagle's autorouter. Run it and see what I don't like. Fix that, usually by moving a component a bit. Sometimes by ripping up a few tangled signals and letting it try again. Sometimes with a bit of manual help, say by pushing a wire or via around.

I often clean things up by hand, but I'm not sure that really matters. It just looks "better" to my eye.

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Reply to
Hal Murray

There are lots of factors involved. Someone I was talking to about this who designs high-spec. boards for many large UK companies told me that they wouldn't accept them if they had been autorouted. Motherboards are made in such vast quantities that the additional costs for manual routing are insignificant. Although I have Electra (supplied with the PCB package I use) I very rarely use it, although it does work better than any other autorouter I've tried.

Leon

Reply to
Leon Heller

Hello Henk,

If the design is noise critical such as most analog circuitry or fast digital areas I don't allow auto routing. I don't do layouts myself but sit with the layouter for critical areas.

It may be ok to autoroute parts of a circuit but most everything I ever designed had sections where it certainly would not be appropriate.

Regards, Joerg

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Reply to
Joerg

I used to work for a well-known large company that designed single board computers (using the high-end Mentor Graphics tools) for telecom applications. We did not use an autorouter at all.

However, a friend of mine tells me that people who really know how to use autorouters can get good results. He used to work with one of these guys. The guy now works (on a contract basis) for a large, US-based PC company and sets up the autorouter to do their motherboards for them. I don't know what tools they use.

I guess the trick is finding the right balance so that you meet skew and signal integrity guidelines, but don't over-constrain the board.

--Mac

Reply to
Mac

or is that layer-outer? 8-)

Do you post from more than 1 computer? Sometimes your posts line-break normally and sometimes they run way past the page edge on the Google archive.

Reply to
JeffM

Hi Jeff,

In some areas they might pronounce it that way ;-)

No, all from one PC. I am using Mozilla. For reasons beyond my understanding it messes up or forgets the line breaks once in a while. With Netscape it was much worse, that sometimes posted blank pages. I have pretty much given up hope that the simple task of line breaks will ever be handled consistently by web software. I have set it to 65 characters but sometimes the software seems to ignore it. Oh well, at least it's right about 95% of the time.

What I also don't understand is why posts with too long lines or missing line breaks aren't formatted to fit the screen at the receiving end.

Regards, Joerg

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Reply to
Joerg

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