Regarding circuit path on a PCB - Page 1
Forum section: electronics / beginners

author: Gunhed
author_rank: Newbie
timestamp: February 25, 2020, 10:27:11 pm
content: Hi,Could someone give me a brief explanation, why it's considered bad practice to have a 90° angle of a printed circuit on a PCB please?Thanks in Advance,Matthias

author: greenpossum
author_rank: Frequent Contributor
timestamp: February 25, 2020, 11:01:38 pm
content: First hit on search:https://resources.altium.com/pcb-design-blog/pcb-routing-angle-myths-45-degree-angle-versus-90-degree-angleTL;DR: Not electrical, more to do with old etching precautions.

author: digsys
author_rank: Unknown
timestamp: February 25, 2020, 11:09:24 pm
content: Quote from: greenpossumA very well written article .. couldn't have done any better. Covers all 3 main "arguments" factually.

author: james_s
author_rank: Super Contributor
timestamp: February 26, 2020, 02:40:47 am
content: For me it's largely a matter of appearance. It's one of those telltale signs that allow one to instantly identify a board laid out by an amateur.

author: Nerull
author_rank: Frequent Contributor
timestamp: February 26, 2020, 08:02:11 am
content: Like the amateurs who designed HP Spectrum Analyzers:For me nothing says "amateur" more than adhering to some method of doing things simply because you've heard about it but without understanding why you're doing it. That's design by imitation, not knowledge.

author: Rerouter
author_rank: Super Contributor
timestamp: February 26, 2020, 08:35:30 am
content: If your pushing the limits of the pcb trace width / spacing your using, they can still suffer from acid-trap type effects, they are also more likely to curl if a fault current cooks a traces, where a curved trace will usually stay put.At the end of the day if your requirements are simple, then as long as it makes a connection your fine, If your requirements are high end level madness, the trace shape is forced a certain way by too many other things.

author: Gunhed
author_rank: Newbie
timestamp: February 26, 2020, 09:08:32 am
content: Thank you for the article!

author: james_s
author_rank: Super Contributor
timestamp: February 26, 2020, 11:18:44 pm
content: Quote from: Nerull on February 26, 2020, 08:02:11 amCoincidentally I was in one of those recently to replace the battery, the CPU board at least has right angles on the edges of the copper pours but I recall seeing a lot of 45 degree bends in the traces themselves, few of which are visible on the top layer. .It's far more nuanced than the rigid adherence to some wives tale you suggest. In practice I view it as a case of "neatness counts". I mean it would not really harm the function of your home if all the sockets and light switches were mounted crookedly and at slightly different heights or if the internal framing was sloppy but those are all signs of amateur construction and I'd wonder what other surprises lurk. The area I tend to focus on is electrical and I can always tell when someone wasn't taught proper technique when I see cables with just the last inch or two of outer sheath stripped off rather than removing it back to within an inch of the box entry as code requires. It works just fine really but it looks sloppy. Same with PCBs, a messy layout may work but it just looks sloppy, it's a sign of poor workmanship and a lack of attention to detail. That doesn't mean you can't ever have a 90 degree bend but in most cases they look sloppy and are best avoided.

author: angrybird
author_rank: Regular Contributor
timestamp: February 26, 2020, 11:41:50 pm
content: So basically some electrons are old and slow and some are young and super fast. And if you make your circuit trace turns too sharp, basically the fast ones can't navigate the turn and they end up going off the road and off into space, which causes EMI. This is the same concept when considering bend radius in coax. If your bend radius is too tight, the centrifical force flings the fast guys right off of the center conductor and they bounce around in the jacket, and sometimes not even quad shield braid is enough to keep them from flinging through the shielding and out into space.Don't listen to anything I just said.