Issue link: https://iconnect007.uberflip.com/i/1524164
86 PCB007 MAGAZINE I JULY 2024 Ultra HDI has become the focus for many fabricators, especially as the follow-on for the 40-year-old conventional HDI. But there is more to UHDI than just finer traces and spaces. Novel architectures have been devel- oped that complement the new dense lithog- Novel Ultra HDI Architectures raphy. Figure 1 shows four of them: 1. Swing blind microvias 1 2. Vertical conductive structures (VeCS) 2 3. Integrated mesh power systems 3 4. Power mesh 4 Happy's Tech Talk #31 by Happy Holden, I-CONNECT007 Figure 1: 1) When using microvias for BGA breakout, the smaller size allows the vias to be "swung" to create larger channels on the inner layers for routings, as seen in A–C; 2) VeCS is a 3D architecture for connections to any inner layer without sequential lamination or plating; 3) IMPS uses the finer traces/spaces and micro- vias to reduce the total layers to only two coplanar layers; 4) Power mesh is similar to IMPS but GND is kept as a return reference layer and the inner layers route signal and power.