A PCB is defined as a number of copper layers in a well defined sequence. Copper layers of a PCB are usually just named layers or also called SIGNAL layer.

However, to define the complete PCB, other layers are required. They are usually named by their functionality and position.

For example: TOP Soldermask layer, TOP paste layer, TOP legend layer, BOTTOM peel-off layer etc…

Copper layers are usually just named layers or also called SIGNAL layer. However to define the complete PCB, other layers are required. they are usually named by their functionality and position. Examples: TOP solder mask layer, TOP paste layer, TOP legend layer, BOTTOM peel-off layer etc…

In general a PCB is classified by the number of copper layers.

Boards that consists of 1 or 2 layers are often called:

  • 1-layer PCB is a  single sided PCB.
  • 2-layer PCB is a double sided PCB.

Boards with no copper layers or with more than 2 copper layers are defined and called by the number of copper layers. Some examples:

  • 0-layer PCB.
  • 4-layer PCB.
  • 6-layer PCB.

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