About 90 degree routing - Page 1
Forum section: electronics / projects

author: danielks
author_rank: Contributor
timestamp: October 20, 2011, 10:23:18 am
content: I have heard many people saying that 90degree routing is not good.Can anyone explain why is it so ? =D

author: Psi
author_rank: Super Contributor
timestamp: October 20, 2011, 10:53:50 am
content: 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.

author: jahonen
author_rank: Super Contributor
timestamp: October 20, 2011, 10:59:21 am
content: Who's Afraid of the Big Bad Bend?Regards,Janne

author: Psi
author_rank: Super Contributor
timestamp: October 20, 2011, 11:05:42 am
content: also,http://www.alternatezone.com/electronics/files/PCBDesignTutorialRevA.pdf

author: Unknown
author_rank: Unknown
timestamp: October 20, 2011, 03:26:44 pm
content: 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.

author: shadewind
author_rank: Frequent Contributor
timestamp: October 20, 2011, 03:45:52 pm
content: My main reason for avoiding it is because it looks ugly.

author: Rufus
author_rank: Super Contributor
timestamp: October 20, 2011, 03:52:08 pm
content: Quote from: Psi on October 20, 2011, 10:53:50 am\ is shorter than L.The shorter the tracks the more tracks you can fit in a given area.

author: Unknown
author_rank: Unknown
timestamp: October 20, 2011, 04:12:20 pm
content: Unless you have a rectangular component or slot in the way.

author: Neilm
author_rank: Super Contributor
timestamp: October 20, 2011, 05:50:21 pm
content: Quote from: Psi on October 20, 2011, 10:53:50 amI always thought it was because the electrons would hit the sharp corner and some would spray out over the PCB making a mess.Neil

author: Psi
author_rank: Super Contributor
timestamp: October 21, 2011, 12:24:22 am
content: Sometimes you see pcbs where all the tracks are curves.It looks really odd.

author: EEVblog
author_rank: Unknown
timestamp: October 21, 2011, 02:41:51 am
content: Quote from: Psi on October 20, 2011, 10:53:50 amBingo!Dave.

author: gregariz
author_rank: Frequent Contributor
timestamp: October 21, 2011, 03:34:50 am
content: Quote from: Psi on October 20, 2011, 10:53:50 amThere'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.

author: Armin_Balija
author_rank: Regular Contributor
timestamp: October 21, 2011, 04:22:47 am
content: 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

author: JuKu
author_rank: Frequent Contributor
timestamp: October 21, 2011, 07:51:01 am
content: 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.)

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 21, 2011, 10:30:45 am
content: Quote from: JuKu on October 21, 2011, 07:51:01 amprofessionals 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".

author: shadewind
author_rank: Frequent Contributor
timestamp: October 21, 2011, 11:29:11 am
content: But 90 degree turns are ugly (scientifically proven by the International Ugliness Standard Organization). So by using 90 degree turns, your board will be ugly and you don't want that, do you? DO YOU?

author: RayJones
author_rank: Frequent Contributor
timestamp: October 21, 2011, 10:22:05 pm
content: 90 degrees looks ugly and reveals slap happy laziness.

author: Zero999
author_rank: Super Contributor
timestamp: October 23, 2011, 05:38:37 pm
content: I always avoid it due to fear of acid traps, even though I've never had a problem before. I was always told to avoid it during my apprenticeship for this very reason. It's the kind of thing which is often nor covered in a typical collage or univrsity course.

author: gregariz
author_rank: Frequent Contributor
timestamp: October 23, 2011, 10:08:18 pm
content: There are no rules for this stuff.PCB vendors these days as a general rule have their etch processes under control so either/or is acceptable. And with a silk screen on quite frankly nobody cares.In my reality I couldn't use only 45 degree or only 90 degree routing even if I wanted to due to compression of designs. All my designs of recent times have both simply because that is all that will fit.