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50 DESIGN007 MAGAZINE I OCTOBER 2024 However, since only partial layers are HDI, these issues are localized to those layers, potentially reducing overall manufacturing complexity compared to full HDI boards. Shaughnessy: Is there anything you would like to add? When considering a partial HDI approach, it's essential to work closely with your PCB manu- facturer to understand their specific capabili- ties, as not all fabrication houses are equally skilled with HDI technology. I cannot stress this point enough. Additionally: • Material selection is crucial, as some materials handle the thermal and mechanical stresses of HDI processes better than others • Signal integrity considerations may need special attention, especially if the HDI layers are used for high-speed signals. Simulation and analysis are key here. Impedance control and careful trace routing are important in partial HDI designs as well • ermal management should be analyzed since HDI layers may affect the overall heat dissipation depending on how the board is layered Ultimately, partial HDI provides a balanced approach, enabling designers to achieve higher densities and performance while managing costs and manufacturing complexity. Shaughnessy: Thanks, Steph. DESIGN007 Introduction One of the biggest challenges facing printed cir- cuit board designers is properly understanding the cost drivers in the PCB manufacturing process, par- ticularly the manufacturing of advanced technology PCBs. Design for Manufacturing (DFM) is defined as the practice of designing printed circuit boards that meet not only the capabilities of the customer's assembly manufacturing process, but also the capa- bilities of the board fabrication process to provide the highest reliability at the lowest possible cost. The guidelines offered in this book are based on both ASC recommendations and IPC standards and apply to standard to advanced technology PCBs. UHDI technology may require violating many of the guidelines included within. It is also understood that some of these guidelines may require adjustment based on the material set, fabricator processes, and other design constraints. While not a substitute for early design engage- ment with the PCB fabricator, in this book the reader will learn about these cost drivers (from the PCB manufacturer's perspective) and the design decisions that will impact product reliability and help companies "design for success." NEW: Visit the I-Connect007 library to continue reading The Printed Circuit Designer's Guide to DFM Essentials. BOOK EXCERPT The Printed Circuit Designer's Guide to... DFM Essentials