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24 DESIGN007 MAGAZINE I OCTOBER 2024 tion requires multiple sequential laminations. So, reducing the circuit layer stackup on each side of the board has a very positive impact on unit cost. New Guidance Standards for HDI and UHDI Circuit Boards IPC-2226 defines HDI as a printed circuit board with a higher wiring density per unit area than conventional PCBs. ey have finer lines and spaces (≤100 µm/0.10 mm), smaller vias (<150 µm) and capture pads (<400 µm/0.40 mm), and higher connection pad density (>20 pads/cm 2 ) than employed in conventional PCB technology. Ultra HDI PCBs are defined as products with conductor widths, isolation distances, and dielectric thicknesses under 50 µm, microvia diameters of less than 75 µm, and characteristics that exceed the existing IPC- 2226 standard. NCAB Group's Jan Pedersen notes that his company "receives inquiries daily concerning printed circuit boards where the requirements for conductor widths and isolation distances are smaller than currently furnished on stan- dard HDI boards." Pedersen initially served as chair of IPC's medical committee, where they discussed the issue of newer requirements and parameters needed for future generations of semicon- ductor components that will require a much higher-density circuit board. e problem was that factories couldn't build a printed circuit board when their customers didn't have the ground rules for designing the circuit board. For the factories to be able to build their capac- ity, they would first need to base their manu- facturing on standard compliance. Discussions gradually evolved and eventu- ally led to the approval of the IPC Techni- cal Activity Executive Committee to form a technical working group of member compa- nies to begin their work. Aer three years of planning by the group, two new documents, IPC-2229 and IPC-6019 for UHDI circuits, have evolved. ese standards documents serve as a guide for printed circuit design engineers and manufacturers fabricating cur- rent and future high-density circuit boards. eir goal is to publish these documents near the end of 2025. DESIGN007 Vern Solberg is an independent technical consultant, specializ- ing in SMT and microelectronics design and manufacturing tech- nology. To read past columns, click here.