Microvias are small plated holes that connect adjacent layers of a PCB. These vias are created using laser drill technology and are generally found in high-density interconnect circuit boards.
Key characteristics of microvias:
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Size: Ranges from 100 to 150 µm
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Typical aspect ratio: 0.75:1
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Via filling material: Often filled with conductive material (like copper) or non-conductive epoxy
Types of microvias:
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Blind: Starts on an outer layer and terminates on the adjacent inner layer.
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Buried: Connects two inner layers and is not visible from the outer surfaces.
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Stacked: Multiple holes are built directly on top of each other to connect across several layers. These vias often require filling for reliable interconnection.
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Staggered: Vias on different layers that are offset from each other, connected through short traces. Generally considered more reliable than stacked microvias.