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Elementary Mr. Watson: Chasing Checkmarks, Not Signal Integrity

For the September 2025 issue of Design007 Magazine on signal integrity, I explored how the PCB is similar to a military obstacle course: walls that sap energy like impedance mismatches, barbed wire that cuts like crosstalk, and mud pits that drag a signal down like attenuation. The takeaway was clear that a PCB is not a flat drawing; it's an electromagnetic ecosystem filled with hazards that test every signal that dares to cross it. The real danger lies not in the obstacles themselves, but in the fact that many designers never see them.

There is a disconnect between reality and what our everyday ECAD software shows, but why? Why is a tool capable of modeling countless layers, stacking 3D bodies, and spitting out a dozen manufacturing formats unable to show us the good, the bad, and the ugly truth of how signals suffer as they run through the PCB?

There are software packages that do this: full-blown signal integrity simulators, field solvers, and electromagnetic analysis tools that reveal the true path a signal takes, warts and all. However, these tools are often outside the core PCB workflow, hidden behind additional licenses, specialized expertise, or steep learning curves. In practice, most designers’ daily CAD tool shows them only geometry, not physics. They are tidy connections instead of the messy, obstacle-course reality.

The first part of the answer is that ECAD tools were never meant to reflect reality; they were intended to manage representation. The trace looks flawless on-screen because the software only cares that it connects two pins without crossing another net. It's a drafting exercise at heart: lines, widths, and layers that satisfy a connectivity checklist. To the designer staring at the monitor, it feels finished. However, that's equivalent to looking at a marathon route map that shows only the streets, without any indication of the terrain. On paper, it appears to be a straightforward run to the finish line, but the actual run is grueling. Some hills burn energy, headwinds slow momentum, and potholes wait to trip you mid-stride. 

The second part of the answer is historical. Early CAD systems weren't born as physics engines or electromagnetic solvers but as digital drafting tables with a simple mission to replace tape and mylar with something faster, cleaner, and easier to update. Engineers who once pulled tape across mylar or drew pencil lines across vellum could now drop digital traces on a grid. Precision was the focus: exact coordinates, crisp lines, error-free connectivity. Success was in producing a clean digital drawing that matched the schematic and could be handed to manufacturing without ambiguity. That DNA still lingers in today's tools.

Unfortunately, the drafting legacy still shapes how CAD works. It rewards neatness over truth. Even though modern platforms now bolt on signal integrity simulators, power integrity analysis, and 3D field solvers, they are still optional extras—tools you run after the routing is "done," not part of every mouse click. The core workflow still celebrates completion: the rats’ nest disappears, the DRCs clear, and the layout looks pristine. What it doesn’t tell you is whether the signal just tripped over an impedance mismatch, lost half its strength to dielectric loss, or collided with crosstalk. CAD celebrates completion—green checkmarks and tidy nets—not comprehension. That is a significant reason why many designs excel in the lab but stumble in the field.

The deeper reason, and one I've made a personal mission to call out, is cultural. For decades, PCB education and workplace habits have conditioned designers to think like draftsmen, not ecosystem architects. From the classroom onward, the emphasis is on producing boards that look correct rather than behaving correctly. Conventional training often reduces "success" to little more than a clean schematic-to-layout handoff, a cleared rats’ nest, and satisfied DRCs. Students learn to chase green checkmarks instead of developing the instinct to ask, “What will the signal experience when it actually runs this course?”

The grading of academic assignments and reviews also reinforces this mindset. Many programs assess the deliverable based on its compilation, correct connection routing, and user error-free fabrication. Few people ask about impedance control, return paths, or crosstalk. In short, the cultural message is: "Get it to work on paper, and let the lab figure out the rest."

The industry echoes this conditioning. On the job, we tell new designers to move fast, keep costs down, and make the design "fit" within the constraints of manufacturing schedules. Managers often measure success by output volume and deadlines met, not by long-term field reliability.

As a result, managers reward entire teams for being efficient drafters rather than thoughtful engineers who see the PCB as an electromagnetic environment. Over time, this creates a cycle where designers are trained, mentored, and promoted for the wrong behaviors, and the hidden physics of signal integrity becomes an afterthought, rather than a core design principle.

The workplace reinforces this mindset. Deadlines demand speed, budgets demand efficiency, and managers often see a PCB as a deliverable package rather than a living electromagnetic environment. In that world, they define success as hitting the deadline, often set by someone who doesn't grasp what it takes to design a robust board, not ensuring that the signals will perform reliably in the field. The reward structure celebrates visible progress—tidy traces, cleared rules, clean BOMs—while the invisible realities of signal integrity remain unexamined.

When you add it all up, a designer's mental model ends up too clean compared to reality. On their screen, the signal glides effortlessly along a pristine highway, free of hazards or surprises. In truth, it's grinding through a military obstacle course. The designer never sees that struggle because their "window" into the PCB is limited to the flat, idealized CAD layout.

Here’s some advice for new PCB designers: Speak to a veteran PCB designer or a signal integrity engineer, and you'll hear a different language. They talk about the path and the environment—the whole journey, not just the route sketched in copper. Until designers learn to see the board in the same way, they'll continue to underestimate how many blows their signals are taking along the way.

John Watson is a professor at Palomar College, San Marcos, California.