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How PCBs are routed

Craft & Design Technology

One hour of PCB routing with EAGLE, compressed to seven minutes, over at adafruit.

10 thoughts on “How PCBs are routed

  1. Andrew says:

    Even at an hour, that’s quick work. Whoever did this clearly isn’t as much of a perfectionist as me, though. I learned Eagle a few weeks ago, and spent a silly amount of time polishing my first substantial layout- making traces parallel, evenly spaced, and at perfect 45 degree angles, minimizing pour orphans, minimizing vias..

  2. Kai says:

    What Andrew said. To get this result you might as well use the autorouter.

    Another important part of routing is component placement. It can make the difference between a big mess of wires crossing all over the place and a neat, clean design.

    1. ladyada says:

      this is a way better handroute than using an autorouter. have you ever used the Eagle autorouter? it makes a ridiculous mess of power/gnd lines because it wont lay down planes for you. i dont know a single electrical/CAD engineer who uses any kind of autorouter, and none of their friends do either. :)

      if you watch the video, you will note:
      there are TWO vias on the board
      the signal lines lengths are minimized (did you see the parts of the video where pins were swapped?)
      signal lines have 45 degree angles (not that it matters at Arduino-speed, of course, but some people think its a big deal)
      there’s a ground plane (autorouters dont put those in for you)
      the components are placed optimally before the video
      finally, its a nice clean design that works great and most importantly was done in 1 hour in time for tacking onto an existing run

      but since you’re saying your routing is better, can you post an example / video?

      1. Anonymous says:

        90 degree angles has nothing to do with signals (well it does at high speeds) but with the actual etching

  3. Bob D says:

    Eagle most definitely will autoroute planes (ground, power, or any other net you want). I use Eagle for RF amplifier design work and I bounce between many iterations of hand placement and autorouting. I tend to work to get parts where they make the most sense, then do a final autoroute and then tweak that by hand since Eagle has no idea what I’m actually doing with my circuit. It won’t know that routing an output of a current mode amplifier or MMIC in parallel with the input is bad mojo. That’s my job. Tweaking the autorouter settings is an absolute must, and I’ll do that several times during a project, as well as several times during the autorouting (I’ll route sections of a board with one set of settings, then make changes, route another section, etc). 0 cost vias for decoupling caps for instance (this takes you right down to the ground plane in most cases, but even this sometimes needs a hand to get right).

    Try routing a 6 layer board with 500+ components and multiple ground planes (analog and digital), 100% surface mount, by hand, in under a day. Using the autorouter effectively allowed me to do it in half a day and the board worked exactly as planned the first time. There have been zero modifications/revisions to this board since because none were needed thanks to a little help from Eagle. No autorouter can do this by itself, and I doubt there are many humans that can do it without an autorouter in this time frame.

    God help ya if you think you can layout something like a PC motherboard by hand in under a few years without an autorouter. God hep ya if you think it’ll work without understanding what you’re doing while using the autorouter.

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Becky Stern is a Content Creator at Autodesk/Instructables, and part time faculty at New York’s School of Visual Arts Products of Design grad program. Making and sharing are her two biggest passions, and she's created hundreds of free online DIY tutorials and videos, mostly about technology and its intersection with crafts. Find her @bekathwia on YouTube/Twitter/Instagram.

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