pcb-rnd knowledge pool

 

Index: using and creating footprints

Ifootprint by Tibor 'Igor2' Palinkas on 2017-12-25

Tags: index, footprint, library, lib, subcircuit

node source

 

 

Abstract: n/a

 

Using existing footprints

Using footprints has two main aspects: library (how/where to get the footprints) and importing from schematics .

Library sources, footprint types

Pcb-rnd has a modularized library support: differnet fp_ plugins access local and remote footprint libraries differenlty. At the end all footprints are accessible through a unified runtime library. Related nodes:

Importing from schematics

When a raw netlist is imported, no footprints are placed, only the netlist is initialized. In an "import schematics", both netlist and footprint names are imported.

Footprint names are typically set as symbol attributes on the schematics.

How to design footprints

Technically

Drawing a footprint is creating a subcircuit . A subcircuit is a generic grouping mechanism that is also used as the footprint implementation in pcb-rnd. Related nodes:

Details to consider

There are a lot of fine details to consider when designing a footprint:

Terminals can be numbered by hand, using the {e t} keys over the terminal, or using scripts such as the termnum script, available from edakrill.

Padstack design

Terminals of a footprint is most commonly created using padstacks. Padstacks are constructed and broken up in a very similar way to subcircuits.

When designing a padstack, you should consider: