The different electronic products have different requirements of reliability, maintainability and density of the boards. With the 3-Tier footprint library construction concept, you can generate footprints to meet the different needs arising from component tolerances, the assembly process and the density of components on the board.

For each component, three geometric variants are provided for the pad dimensions and component profile: most material condition (low density, level A), nominal material condition (medium density, level B), least material condition (high density, level C).

The name of the footprint must end with a letter that identifies the level of belonging.

Level Description Name suffix for SMD footprint Name suffix for THD footprint

Low density, level A

For low density PCBs, the maximum pad size is used.



Medium density, level B

For medium density PCBs, the nominal pad size is used.



High density, level C

For high density PCBs, the minimum pad size is used.




For information on the 3-Tier PCB library, refer to the IPC-7351 standard.

To create a 3-Tier footprint

All three footprints must reside on the same page.


When you import a footprint from the libraries, the model corresponding to the construction level of the board, set in the parameter IPC Level in the dialog PCB Layer Stackup, is automatically selected.

Example page for SMD component

Example page for THD component

See also