What is a Via?

A Via is used to make an electrical connection between the layers of a Multi-Layer PCB. Connecting multiple layers of a board makes it possible to reduce the size of the PCB, as layers can be stacked. A via is constructed by placing copper pads on each layer of the PCB and drilling a hole through them. The hole is made conductive through electroplating or by placing copper cylinders directly in the drilled holes.

The inner part of the via is usually filled with a non-conductive material (air in most cases), while the outer layer of the cylinder has a conductive plating which is used to connect each layer of the PCB.

Note: It is always good to use multiple smaller vias rather than one large via since it reduces the inductance and also provides an additional path to the current flow in case any of the vias fail.

Types of Vias

There are three main types of Vias used in a Printed Circuit Board:

Through-Hole Via: This Via goes right through the PCB board from top to bottom and can be used to connect all the layers of a PCB. It is the most common via and is easiest to construct.

Blind Via: This Via connects the outermost layer of a PCB to the next layer. It can not be seen on the other side of the board and is therefore called blind via.

Buried Via: This Via can be used to connect internal layers of a PCB. It is not seen on the surface of the board.