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MARCH 2026 I I-CONNECT007 MAGAZINE 37 T H E C H E M I CA L C O N N ECT I O N Step 3: Developing This is the simplest, most foolproof step in the pro- cess. If the exposure has been done properly, then the working window is extremely wide. Almost anything that doesn't leave resist in the traces or lift the resist off the panel is okay. For good results, you just need a simple pH monitor. Money spent on planned developer improvements might be bet- ter spent on improving the exposure process. Step 4: The Etch Process We get to the etch process just as we are running out of column space, but that would take a book to write about, and I have no plans for a book at the moment. I find doing a monthly 1,200-word max column quite enough of a challenge. However, here's a tip, gained from long experience, that will save you some time: Simply changing spray nozzles in the etcher or changing etch chemistry will not improve your etch tolerances. You may get a faster etch rate or better etch factors, but the etched line width tolerances will not be improved. There is no process step I know of that improves total variation. As the computer boys say, "garbage in, garbage out." I-CONNECT007 Don Ball is a process engi- neer at Chemcut. To read past columns or contact Ball, click here. Beyond the Board: How Advanced PCB Design Is Reshaping Mil/Aero Electronics As mil/aero electronics evolve toward higher data rates, greater processing density, and tighter mechanical envelopes, integration is no longer occurring primarily at the box level, but rather deep within the electronic architecture it- self, often beginning at the printed circuit board. While software-defined capabilities, advanced sensors, and cutting-edge platforms tend to dom- inate public discussion, the physical layers that enable these technologies are quietly absorbing unprecedented technical demands. The PCB is no longer just an interconnect plat- form. In many modern defense systems, it has become a performance driver. Electronic Density Is Climbing Fast Shrinking form factors and rising functionality are pushing board designs toward higher layer counts, finer geometries, and more complex stackups. It is no longer unusual to see construc- BY J ES S E VAU G H A N , S U M M I T I N T E RC O N N ECT tions supporting dense BGAs, high-speed serializ- ers/de-serializers, RF sections, and power-dense components on the same board. This convergence creates competing require- ments. Signal integrity must coexist with power integrity. Thermal performance must be managed without sacrificing routing efficiency. Controlled impedance structures must remain stable across increasingly sophisticated lamination cycles. At higher frequencies, even small variations in di- electric thickness, resin content, or copper profile begin to matter. Margins narrow quickly. Design teams understand this. What is changing is how early those constraints must be acknowl- edged. Boards that appear electrically sound in layout can become far more sensitive once fabri- cation tolerances, material behavior, and sequen- tial lamination realities enter the equation. Continue reading here.