Via (electronics)

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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.

In IC[edit]

In integrated circuit design, a via is a small opening in an insulating oxide layer that allows a conductive connection between different layers. A via on an integrated circuit is often called a through-chip via. A via connecting the lowest layer of metal to diffusion or poly is typically called a "contact".

Where possible, redundant vias are often added to improve the reliability of the circuit and enhance the manufacturing yield.[citation needed]

In PCB[edit]

Different types of vias:
(1) Through hole.
(2) Blind via.
(3) Buried via.
The grey and green layers are non-conducting, while the thin orange layers and vias are conductive.
PCB Via current capacity chart showing 1mil Plating Via Current Capacity & Resistance vs Diameter on a 1.6mm PCB

In printed circuit board design, a via 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:

  1. Barrel — conductive tube filling the drilled hole
  2. Pad — connects each end of the barrel to the component, plane or trace
  3. 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.[1]

Gallery[edit]

Plated-through holes, in this section there are eight on a multilayer board (magnified) 
Double layered plating in CAD. Vias makes EDA placement possible.
Bottom layer – Red
Top layer – Blue 
Plating of plated-through holes:
Above – Top layer
Down – Bottom layer 
Cut section of a multilayer via 
The small metallic circles are vias 

See also[edit]

External links[edit]

PCB Vias Design guidelines[edit]

Notes[edit]