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18 DESIGN007 MAGAZINE I JUNE 2023 Feature Q&A by Andy Shaughnessy I-CONNECT007 If you're a fabricator, chances are you have a few things to say about at least a few of the PCB designs that make their way through your shop. I guarantee that you have several well-worn stories about designs that made you scratch your head and think, "Hmmmm." So, in this section, we asked PCB fabrica- tion experts to share their thoughts about chal- lenges that PCB designers need to more thor- oughly understand. Do you see yourself on either side of these issues? Dana Korf Korf Consultancy LLC What is your main concern for PCB designers? Impedance and signal loss variability. In recent years the signal integrity that RF designers were very concerned about is now becoming a requirement in standard digital and analog designs. Simulation tools are used to char- acterize the design nominally and against high and low tolerances of the key specifica- tions. en a quick prototype is fabricated and tested. Several iterations may be built and assembled until the proper answer is achieved. e signal performance can be affected by the drilled/lased hole's inner diameter, plated diameter, material dielectric thickness and electrical properties, solder mask, Dk and thickness, trace-width tolerance, and to a lesser extent its thickness. Yet, the fabricator is rarely required to provide this information to the designer. So, the designer doesn't know if the PCB was built at the high-end, low-end, or middle of the tolerance range. Designers oen complain that a new revision or build didn't perform like the last version. Of course, it may not. e reason is most likely due to fabrica- tion tolerances. When the design has tight impedance or loss requirements the designer should require more information about the received PCB crit- Dana Korf DESIGN CHALLENGES: From the Fabricator's Viewpoint