Vias connect copper layers in a PCB, but different via types create different design and manufacturing consequences. The useful decision is which via structure is needed for the routing problem and which one adds unnecessary cost or risk.
Through holes are the simplest starting point
A through via connects from the top layer to the bottom layer. It is usually easier to manufacture and inspect than blind or buried structures, but it also consumes routing space through the whole board.
For broader layout context, see PCB layout knowledge.
Blind and buried vias support density
Blind vias connect an outer layer to an inner layer. Buried vias connect internal layers without reaching the surface. These structures can free routing space, but they may require additional lamination and tighter process control.
If the design needs more routing density, any-layer HDI manufacturing checks are relevant.
Microvias should be used with a reason
Microvias can help with fine-pitch package escape routing, but they should be reviewed for stackup, reliability, and inspection method. Stacked and staggered structures should not be selected without confirming supplier capability.
For high-layer designs, high-layer PCB stackup checks can help evaluate the via strategy together with layer count.
Questions before design release
Confirm which layers each via connects, whether controlled impedance is affected, whether the via creates a return-path issue, and how the manufacturer will inspect the structure.