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AUGUST 2026 I I-CONNECT007 MAGAZINE 35 argument here is that earlier collaboration changes the process from error correction to much more cost-effective error prevention. Some Thoughts on RF and HDI RF and HDI designs are often treated as special- ized classes within the larger PCB discipline. That classification is useful, but it can also create artifi- cial boundaries. We have learned through hard lessons that RF performance depends not simply on trace geom- etry, but also on laminate properties, base copper roughness (top and bottom), plating thickness and uniformity, connector selection, fabrication toler- ances, and assembly consistency, along with other more arcane concerns. The RF designer, PCB designer, material supplier, fabricator, and test engi- neer must therefore participate in a shared and interactive design process. HDI (and now more frequently UHDI) presents a similar challenge. Microvias, sequential lamina- tions, few-micron lines, few-micron-thick dielectrics, microvia-in-pad structures, and stacked and/or stag- gered interconnects collectively expand routing capability, but they also affect cost, yield, reliability, and perhaps most importantly, supplier availability. There are simply not that many suppliers for such a product, especially in North America. An HDI architecture cannot be responsibly selected solely because it makes routing easier. Nor should it be rejected solely because it appears more expensive on a per-panel basis. The architec- ture must be evaluated, again in terms mentioned earlier, in the context of total product size, layer count, assembly methods, yield, electrical perfor- mance, testing, reliability expectations, and produc- tion volume. This same principle applies to almost every advanced PCB technology. Its value cannot be understood from the perspective of a single disci- pline; thus, manufacturing must become a true design participant, not an observer. Conclusion Manufacturing is frequently positioned at the end of the design chain, where its role is to determine whether the completed design can be built. This is the traditional home of DFM. Sadly, the fabrica- tor is only asked to approve or reject a finished design and is being used as an inspector rather than as an engineering resource. They can offer so much more. Experienced, top-tier fabricators are invalu- able resources, possessing detailed knowledge of material behavior(s), registration capabilities, drilling and plating limits, imaging processes and their limitations, material movement during lami- nation, copper distribution concerns and recom- mendations, impedance control, and myriad other potential defect mechanisms. In addition, and not yet covered but very important, assembly special- ists understand stencil design, solderability, package behavior, component warpage, thermal profiles, cleaning constraints, rework risks, and inspection limitations. That combined knowl- edge (manufacturing and assembly) provides its greatest value before the design architecture is fixed, which nicely sums up the purpose of this (hopefully) brief commentary. At the end of the day, unless we collectively understand the limitations of DFM and the poten- tial of DWM, we will continue to miss the target. DFM asks whether a design can be manufactured. DWM teaches how a product can be jointly opti- mized for performance, manufacturing, assembly, reliability, inspection, cost, supply resilience, and lifecycle support. In short. DFM rules are applied to the design, and DWM, or co-design, shapes the design to get it right the first time. The distinction is fundamental. I-CONNECT007 Joe Fjelstad is founder and CEO of Verdant Electronics and an international authority and innovator in the field of electronic interconnec- tion and packaging tech- nologies with more than 185 patents issued or pending. To read past columns or contact Fjelstad, click here. Download Flexible Circuit Technology, 4th Edition, and watch Fjelstad's in-depth workshop series "Flexible Circuit Technology." FLEX007 | F L E X I B L E T H I N K I N G F L E X I B L E T H I N K I N G