Associating components and foot prints:
In schematic creations, we used only components like microcontrollers, capacitors, pots etc. These are component symbols, but their practical shape is comparatively different. Moreover, components have different shapes, dimensions, and pin structures. By looking at these symbols, we can determine the type of physical properties but in PCB designing, component physical dimensions are very important. So, for each component symbol in schematic, we must assign suitable footprints.
Footprint: Footprint, also called land pattern, is used to attach a component physically and electrically to a printed circuit board.
After finishing schematic without errors, we have to assign suitable footprints for every component used in schematic. In this tutorial, we will see how to select footprints, how to create new footprints and how to add footprints to the components.
Open CvPcb by clicking on the icon . A new window will appear with footprint libraries and with component names used in schematic. Select the component in that list. The related libraries will appear at the right side in the window. In those libraries, we have to find the suitable footprint. If libraries are not matched or no suitable libraries are displayed, then deselect “footprint list by keywords” and “footprint list by components” options in the toolbar and select footprint list by the library. Now select any library in the list which is present at the left side of the window. The library components can be seen at the right side of the window.
In that list, select any component and check it by opening in footprint viewer. Here, we can see the footprint in 2D, with component silk mask and pads. Still, if it’s not clear, we can view the footprint in 3D as well. Check the footprint dimensions and its type; if it is a suitable footprint, add it to the component. Repeat the same procedure for all components.
If no suitable footprint is found, then we have to create a new footprint. To create a new footprint, open footprint editor in Eeschema window or in KiCad main window. Footprint editor window will appear on the screen.
Fig. 1: Screenshot of KIcad PCB Design Tool
Click on “new footprint” icon to edit and design and give footprint name in the window, for example, Switch.
Fig. 2: Screenshot of New Footprint Window
Start editing by drawing a shape using add graphic line or any shape options available at the right side of the window.
After completing the shape, add the pads. Select place pad option and click wherever the pad has to be placed. To edit the pad, select edit pad in right click options. In the window, select type of the pad (SMD, through Hole, connector etc) and orientation copper layers options as per requirement and assign any name, click ok. Repeat the same procedure for remaining pads also. After everything is complete, save the footprint.
Fig. 3: Screenshot of Pad Properties in KIcad
Now we can see this new footprint in the library, which is then added to the component.
After assigning footprints to all components, save the list and close the window.
Filed Under: Tutorials