Multi layer PCBs have besides OUTER layers (see point 6) a number of copper layers between the TOP and BOTTOM copper layer. These copper layers are defined as INNER layers. The sequence in which the INNER layers need to be produced is important and is determined by their naming. This is usually done by numbering them from 2 till …. Example of the naming of the layers of a 6-layer PCB:

  • TOP layer
  • INNER 2
  • INNER 3
  • INNER 4
  • INNER 5
  • BOTTOM layer

Important is that the naming or name extensions of the files which contain the layout data is clear and understandable for any PCB manufacturers Computer Aided Manufacturing software and his pre-production engineers. Read also “PCB design Guidelines” page 11.

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