As electronic devices shrink while functional requirements expand, traditional through-hole PCB architectures often reach a physical routing limit. High-Density Interconnect (HDI) technology is the industry’s answer to this bottleneck. At DUXPCB, we view HDI not just as a manufacturing process, but as a strategic design shift that enables superior signal integrity and extreme miniaturization.

The transition to HDI is typically triggered when component pitches drop below 0.5mm or when BGA (Ball Grid Array) escape routing becomes impossible on standard 4-6 layer boards. Unlike traditional PCBs that rely on mechanical drilling, HDI utilizes laser-drilled microvias and sequential lamination to achieve higher connection density per unit area.

1. Microvias: Defined by IPC-2226 as holes with a diameter ≤0.15mm. These are typically laser-ablated and connect only two adjacent layers.
2. Blind Vias: Connect an outer layer to at least one inner layer without penetrating the entire board.
3. Buried Vias: Connect two or more inner layers, completely hidden from the external surfaces.
4. Sequential Lamination: The process of bonding sub-structures in multiple stages to allow for complex via-in-pad and stacked via configurations.

• Type I (1+N+1): A single microvia layer on both sides of a core.
• Type II (2+N+2): Two microvia layers, which may be staggered or stacked.
• Type III: Includes at least two layers of microvias on one or both sides, often utilizing buried vias within the core.

While many manufacturers push designers toward high-layer counts (12+) for complex routing, our engineering team specializes in optimizing 2-8 layer HDI designs. We recognize that for many IoT, medical, and wearable applications, a well-engineered 6-layer HDI board can outperform a standard 10-layer board in both cost and thermal performance.

Our manual review process identifies potential "traps" in your HDI layout, such as:

• Stacked vs. Staggered Vias: We often recommend staggered microvias to reduce thermal stress and improve yield unless space is critically limited.
• Material Compatibility: Selecting the right high-Tg (Glass Transition Temperature) materials that can withstand multiple lamination cycles without delamination.
• Thermal Vias: Strategically placing microvias to act as thermal conduits in high-power density areas.

HDI is no longer a luxury for high-end aerospace; it is a necessity for modern hardware. By mastering microvia structures and adhering to IPC-2226 guidelines, designers can achieve 30-50% board area reduction while improving EMI performance.

Our engineering team at DUXPCB is ready to assist you in transitioning your 2-8 layer designs into high-reliability HDI masterpieces. Contact us for a technical consultation on your next stackup.