Via & MicroVia in electronic Printed Circuit boards
A via (Latin for path or way) is an electrical connection between layers in a physical electronic circuit that goes through the plane of one or more adjacent layers.
A MicroVia is simply a smaller Via with extra rules
In printed circuit board. It consists of two pads, in corresponding positions on different layers of the board, that are electrically connected by a hole through the board. The hole is made conductive by electroplating, or is lined with a tube or a rivet. High-density multi-layer PCBs may have microvias: blind vias are exposed only on one side of the board, while buried vias connect internal layers without being exposed on either surface. Thermal vias carry heat away from power devices and are typically used in arrays of about a dozen.
A via consists of:
- Barrel conductive tube filling the drilled hole
- Pad connects each end of the barrel to the component, plane or trace
- Antipad clearance hole between barrel and no-connect metal layer
A via may be at the edge of the board so that it is cut in half when the board is separated; this is known as a castellated hole and is used for a variety of reasons, including allowing one PCB to be soldered to another in a stack.
Â source page http://en.wikipedia.org/wiki/Microvia