Author Topic: About 90 degree routing  (Read 2165 times)

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Offline danielks

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About 90 degree routing
« on: October 20, 2011, 09:23:18 PM »
I have heard many people saying that 90degree routing is not good.

Can anyone explain why is it so ? =D

Offline Psi

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Re: About 90 degree routing
« Reply #1 on: October 20, 2011, 09:53:50 PM »
I've heard its bad for RF design, but i dunno if that's true.

Another issue is a track is more likely to lift up at the corner when it's a hard 90+ angle, although it's not so much of a problem with modern boards as the tracks are stuck on the pcb much better than they used to be.

Mainly it's considered bad practice and looks unprofessional.

45deg is what pretty much everyone does.
« Last Edit: October 20, 2011, 10:01:58 PM by Psi »
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Offline jahonen

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Re: About 90 degree routing
« Reply #2 on: October 20, 2011, 09:59:21 PM »

Offline Psi

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alm

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Re: About 90 degree routing
« Reply #4 on: October 21, 2011, 02:26:44 AM »
It can give problems with etching (acid trap), although this is mainly an issue for people etching their own boards. I would expect the professional processes to be sufficiently refined that they won't have these issues.

From signal integrity point of view I agree with people with much more experience like Howard Johnson, from my research it doesn't appear to be an issue until at least the multi-GHz frequencies.

Offline shadewind

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Re: About 90 degree routing
« Reply #5 on: October 21, 2011, 02:45:52 AM »
My main reason for avoiding it is because it looks ugly.

Offline Rufus

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Re: About 90 degree routing
« Reply #6 on: October 21, 2011, 02:52:08 AM »
45deg is what pretty much everyone does.

\ is shorter than L.

The shorter the tracks the more tracks you can fit in a given area.




alm

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Re: About 90 degree routing
« Reply #7 on: October 21, 2011, 03:12:20 AM »
Unless you have a rectangular component or slot in the way.

Offline Neilm

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Re: About 90 degree routing
« Reply #8 on: October 21, 2011, 04:50:21 AM »
I've heard its bad for RF design

I always thought it was because the electrons would hit the sharp corner and some would spray out over the PCB making a mess.  ;D

Neil
Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe. - Albert Einstein

Offline Psi

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Re: About 90 degree routing
« Reply #9 on: October 21, 2011, 11:24:22 AM »
Sometimes you see pcbs where all the tracks are curves.
It looks really odd.
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Offline EEVblog

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Re: About 90 degree routing
« Reply #10 on: October 21, 2011, 01:41:51 PM »
Mainly it's considered bad practice and looks unprofessional.

Bingo!

Dave.

Offline gregariz

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Re: About 90 degree routing
« Reply #11 on: October 21, 2011, 02:34:50 PM »
I've heard its bad for RF design, but i dunno if that's true.


There's an impedance discontinuity at a right angle (cap of track changes at that point), but it won't be a problem generally under a GHz. I routinely work at several GHz and will either bevel the edge or lay a round corner of a decent radius. I tend to avoid these bends more for reasons of coupling than anything else ie its most likely to be kept to a min if the signal path is a straight line. As always depends on the exact circuit - you often get away with things and these are just rules of thumb to maximize your chances of coming out the other end alive.

Offline Armin_Balija

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Re: About 90 degree routing
« Reply #12 on: October 21, 2011, 03:22:47 PM »
I've noticed the PCB designs I've done look a lot nicer with 45 degree tracks instead of the hard and sharp 90 degree ones. I just tend to stay away from them now because I feel like they are actually harder to work with when placing tracks.

I also love the look of a board when all the tracks are 45 degree bends. Looks nice and electronicy  :P

Offline JuKu

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Re: About 90 degree routing
« Reply #13 on: October 21, 2011, 06:51:01 PM »
As noted, you can make tighter layouts with 45 degrees routing, and that's why it is the norm. Doing 90 routing is against the norm and therefore looks unprofessional, so it is very bad, mostly in the eyes of your boss and co-workers.

(Btw, the electrons in the PCB tracks move typically a fraction of mm per hour.)

Offline Mechatrommer

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Re: About 90 degree routing
« Reply #14 on: October 21, 2011, 09:30:45 PM »
Doing 90 routing is against the norm and therefore looks unprofessional, so it is very bad, mostly in the eyes of your boss and co-workers.
professionals reason with facts, not eye. so, the professional writing linked by jahonen, stated there's not much problem there unless if you'r working with multi GHz circuit, and of course as you said. looks bad to the eye of clueless boss. most big names in history are "against the norm".


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