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28 DESIGN007 MAGAZINE I JUNE 2025 Feature Article by Stephen V. Chavez SIEMENS EDA Here is a common misconception held by those who don't fully understand the PCB lay- out process or how to wield today's high-level EDA tools: "All I need to do is push the auto- router button, let the computer route all the signal traces, and get the layout 100% routed. It's a no-brainer. Anyone can do it. It should take less than a few hours." Well, sure, if you're in a hurry to check the box indicating you're finished with the layout. But your results will look like a plate of spa- ghetti and most likely not function correctly, if at all, while not passing SI/EMC testing. Good luck with that mindset and methodology. As you can see, there's a lot of confusion about autorouting. I will discuss routing and autorouting in general terms, my initial dis- trust of routers, and the aha moment that changed my mind. en, for specific auto- routing techniques, I will focus primarily on the Siemens autorouter. Routing vs. Autorouting Let's start by setting the baseline for "rout- ing" regarding signal traces. Traditional rout- ing is done by manually connecting (routing) all signal traces from point to point, mouse click by mouse click. en, we manually make any trace constraint modifications/adjust- ments as necessary to meet the design require- ments. Once 100% routing is achieved, a design rule check (DRC) is performed, and all flagged errors must be addressed—aer the fact. is legacy methodology is very labor-intensive and time-consuming, to say the least. e form of routing most utilized today is "manual interactive routing," with only a few higher-end tools possessing automation- assisted interactive routing capabilities. is manual interactive routing is a combination of human effort, along with soware tool utiliza- tion, and some limited automation. e key here is that the user is manually performing Why I Finally Embraced Autorouting