PCB Structures: Vias, Pads, Lands, Traces, and Planes

This Gold Phoenix PCB Knowledge Center article defines PCB structures and terms a designer needs to complete a PCB design, including vias, pads, lands, traces, and planes.

Vias

A via is a physical piece of metal that makes an electrical connection between layers on the printed circuit board. Vias can carry signals or power between layers using plated through holes (PTH Technology). Using this technology, a via is formed by drilling a hole through the layers to be connected and then plating the inner surface of the drilled hole. Vias should be sized according to the traces they are connecting between layers and ultimately how much power they must carry.

Another via technology is High Density Interconnect (HDI). This technology forms a connection between layers by deforming the copper with a laser. These “microvias” cannot penetrate more than one or two layers. This means that microvias must be stacked or stair-stepped in order to make a connection through the entire PCB.

Pads or Anti-Pads

Pads are small areas of copper in predetermined shapes normally used to make a connection to a component pin. In some cases, an anti-pad is needed, which means the predetermined shape is removed from the copper. Generally, an anti-pad is used around a via to isolate it from a power plane where a connection is not needed.

Lands

If you took all the pads needed to solder a component to the top or bottom layer of the printed circuit board, it may be referred to as a land. Making electrical connections throughout the entire board may require vias. When using plated through hole technology, vias are not included in the land pattern. The general method is to use a small trace to connect the land and via to make the appropriate electrical connection.

Traces or Tracks

A trace is a piece of copper, like a wire, that makes an electrical connection between two or more points on a PCB. Traces carry current between these points on the printed circuit board. You will often see people in the PCB design industry refer to traces as tracks. These are synonymous with each other and may be used interchangeably.

Planes

A plane is an uninterrupted area of copper covering the entire PCB layer. It is common to have cuts in a plane in order to distribute different power forms to the PCB components needed. It is critical that good PCB design practices be followed when making cuts in power or ground planes.

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