Microvia
What Is a Microvia?
A microvia is a very small via — typically 150 micrometers (6 mils) or less in diameter — that connects adjacent layers in a PCB stackup. Unlike mechanically drilled vias, microvias are created using laser drilling technology, which enables the precision required for such small features. Microvias are a defining characteristic of HDI (High Density Interconnect) PCB technology and are essential for routing modern fine-pitch BGA packages with ball pitches of 0.5mm or smaller, where conventional through-hole vias are simply too large to fit between pads.
Microvias can be stacked (placed directly on top of each other across multiple layer transitions) or staggered (offset from each other on adjacent layers). Stacked microvias provide the most compact vertical interconnect but require filled and planarized vias at each level, adding manufacturing complexity. The reliability of microvias depends on proper copper fill, absence of voids, and adequate capture pad size — all of which are governed by the fabricator's process capabilities and the designer's adherence to the manufacturer's design rules.
Microvia-Aware AI Layout Generation
Routing designs that require microvias demands intimate knowledge of HDI manufacturing rules and layer-pair constraints. Physics-driven layout engines incorporate microvia design rules into their generation algorithms, automatically selecting appropriate via types based on the layer transition, available pad geometries, and the target manufacturer's HDI capabilities. This ensures that generated layouts use microvias only where they are needed and where they can be reliably manufactured, avoiding the over-use of expensive HDI features that can inflate production costs unnecessarily.






