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JUNE 2026 I I-CONNECT007 MAGAZINE 15 conventional multilayer architecture can sometimes be achieved with ELIC in 12 to 14 layers, because every layer is genuinely usable for routing. That is a meaningful reduction as it affects board thick- ness, material cost, lamination cycle count, and the mechanical profile of the final assembly. The most important perspective shift for ELIC designers is understanding the gap between design capability and production reality (Table 1). From our production experience at ASC, ELIC becomes genuinely compelling when three condi- tions converge: component pitch below 0.35 mm, layer count demands beyond what a 2-4-2 or 3-2-3 configuration can support, and board real estate constraints that prevent spreading components to ease routing pressure. When all three are present, ELIC is often the only viable architecture. The feasibility question is more nuanced than the theoretical ceiling suggests. Minimum capability is not the same as production capability. Designing at the absolute process limit—minimum vias, minimum dielectrics, minimum mask clearances everywhere— is a reliable path to yield loss. The better question is what the fabricator's comfortable production range is, not the theoretical minimum. What Are the Biggest Manufacturing Challenges in ELIC? When customers ask about the single biggest chal- lenge in ELIC vs. traditional stacked or staggered microvia HDI, it's not any one variable. It is the com- pounding relationship between variables that would be individually manageable in simpler architectures but become interdependent failure modes in ELIC. Small variations do not stay small; they stack. Registration Across the Entire Stack Registration is the ability to hold intended positional relationships between features during fabrication: copper layer to copper layer, drilled features to capture pads, and solder mask openings to copper. Figure 2: ELIC is built from the center outward; each cycle adds one layer to the top and one to the bottom. A ~4 µm positional shift introduced at any cycle propagates outward through every subsequent build. By Cycle 6, the outermost layers carry the full accumulated drift of ~20 µm, consuming most or all available capture pad margin in a 50–75 µm ELIC design.