This technology is primarily used in the design and fabrication of HDI PCStacked vias. It’s used to connect very small diameter vias (via in-pad of surface vias to inner layers) in order to route fine pitch components.
Via in-pad micro vias play a key role in shrinking PCB size. These holes are not to be used for inserting a component lead or any other reinforcing material. However, the ability to place components either on or off the pads gives the designer greater flexibility to selectively create routing room in denser parts of the substrate.
Sequential Lamination of PCB layers is required in order to connect outer surface vias. This is due to the nature of the very small drill, and the aspect ratio requirement on all drills (example 10:1) down to the inner layer. This process is usually associated with via in-pad technology when routing fine-pitch, densely-routed designs.
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