Issue link: https://iconnect007.uberflip.com/i/1539283
22 DESIGN007 MAGAZINE I SEPTEMBER 2025 E L E M E N TA RY, M R . WATS O N crisp color. But look closer, and your PCB is a patchwork of uneven terrain, changing widths, inconsistent dielectric properties, and electro- magnetic crossfire—its own military-grade obsta- cle course complete with levels of difficulty that would make even the most brutal drill sergeant raise an eyebrow. I'd even say the PCB is an electromagnetic eco- system. Some ask, "Isn't a PCB just a flat sheet of fiberglass with some copper glued on it?" No. Fiberglass is not flat. Every part—traces, vias, planes, components, solder mask, and the spaces between the different layers and materials—plays a role in shaping the environment your signals have to survive in. Additionally, nothing exists in isola- tion. A tiny change in one area can ripple through the entire system. When you look at the PCB like signal integrity does, you stop seeing pretty copper traces and the terrain the signal has to survive. From the moment a signal launches, it's all good—sharp edges, per- fect timing, full of energy, and practically whistling as it leaves the source. It's the PCB equivalent of a fresh-faced recruit jogging to the starting line thinking, "This won't be so bad." Like an obstacle course, the signal launches off the starting line, running down that first trace. It hits the first obstacle—the high wall—of what will become many impedance mismatches at full speed, only to realize it can't pass cleanly through. Instead, it has to scramble, clawing at the surface, burning precious energy. While it's struggling, a whole chunk of energy doesn't make it. That por- tion bounces back the way it came, ricocheting toward the source as a reflection, ready to cause trouble for the next recruit on the starting line. From the signal's perspective, this isn't just tiring; it's destabilizing. The smooth, consistent rhythm from the starting line is now disrupted. It's breath- ing harder, its edges are less crisp, and it knows there are more obstacles ahead. The wall might be behind it now, but the loss here will echo (literally) through the rest of the run. No time to wallow in self-pity; the next obstacle awaits: low crawl under barbed wire. Now, the sig- nal drops to the ground, forced into a tight crawl. The barbed wire of crosstalk—the electromagnetic mutterings—hangs overhead with sharp jabs from nearby traces. Every inch forward brings a risk: lift its head too high and the barbs bite; stray too far sideways and it's clipped by the chatter of an aggressive neighbor net. The air is thick with interference. Parallel "run- ners" on adjacent lanes shove at its sides, sending jolts of unwanted energy into its path and distort- ing its form, pulling it further from its clean, confi- dent starting shape. Let's say the skin effect kicks in—the signal is stuck hugging the surface, wish-