KiCAD Footprints

The footprint is defined as the physical interface among components or land patterns and printed circuit boards which is also comprising of the information of documentation such as reference, polarization mark, and outline. The land patterns are either derived from the dimensions of the component’s tolerances included or taken from the datasheet. This all is as per the standards of the industry. Most probably the land patterns are also derived from the same standard. It must have all of the connection points which are known as pads for soldering all of the components over sit. The size, position, and shape of the pads must be aligned with the specifications of the datasheet for avoiding faults.

Step 1: What Are KICAD Footprints?

- A footprint or land pattern is the arrangement of pads (in surface-mount technology) or through-holes (in through-hole technology) used to physically attach and electrically connect a component to a printed circuit board. The land pattern on a circuit board matches the arrangement of leads on a component.

- Component manufacturers often produce multiple pin-compatible product variants to allow systems integrators to change the exact component in use without changing the footprint on the circuit board. This can provide large cost savings for integrators, especially with dense BGA components where the footprint pads may be connected to multiple layers of the circuit board.

- Many component vendors provide footprints for their components, including Texas Instruments, and CUI. Other sources include third party libraries, such as SnapEDA.

Step 2: What Is the Difference Between Symbols and Footprints?

Symbols:

Symbols abstract the function of a component and communicate the interface of it to both KiCad and the person reading the schematic. To do this it at least needs to define the connection points for the schematic with so-called pins. It is suggested to add some artwork to the symbol to do this effectively. The easiest symbol is a so-called black box symbol. It simply surrounds the symbol with a box with every pin having a meaningful name shown. For some symbol classes, there are standards that define how such symbols could look like. (As with all standards, they are incompatible to each other. Be inspired by the standard that fits you.)

Footprints:

Footprints define the physical interface between the PCB and the component (The land pattern) and also include documentation information (outline, polarization mark, reference, …) The land pattern is either directly taken from the datasheet or derived from the dimensions of the components (including tolerances) via industry standards. (most likely the suggested land pattern is derived from such a standard as well.) It at least needs to contain all the connection points (called pads) to solder the component to. (Shape and size/ position of the pad should align with what is given in the data

Step 3: Connecting Symbols to Footprint.

- In KICAD the connection is done via the pin number given to the pins in the symbol and the pad number given to the pads in the footprint.

- The pin/pad “number” is not necessarily a number. In KICAD4 it can be any string of length less than 4. In KiCad 5 this length limitation will be dropped.

- The second part of the connection is made via the footprint field of the symbol.

- This field can be set either when creating the symbol (fully specified symbol) or later when it is already placed in eeschema. (generic symbols)

- For generic symbols, there are two ways to select the footprint. Either via the symbol properties dialog/footprint browser or via cvpcb.

Step 4: How to Create Your Own Footprint.

First step: Click the new footprint from the upper bar.

Step 5: How to Create Your Own Footprint.

Second step: click on the new footprint from the upper bar in the footprint editor.

Step 6: How to Create Your Own Footprint.

Third step: enter the footprint name as in the following photo.

After that click OK, and it will appear on the screen.

Step 7: How to Create Your Own Footprint.

Fourth step: click on the File menu to create a new library. " you will create this library to save the project in it"

Step 8: How to Create Your Own Footprint.

Fifth step: name the library and detect its location

Step 9: How to Create Your Own Footprint.

Sixth step: drawing a footprint as something that represents the top-down view.

Step 10: How to Create Your Own Footprint.

Click place then choose pad.

Click on double click to edit this pad.

Edit the pad as the following and then click OK.

Step 11: How to Create Your Own Footprint.

- Finish drawing and editing of pads.

- Drawing the connecting lines between them by clicking the place menu and choosing line.

- Last step: drawing the notch at the end of this IC by clicking on place and choose arc.

Step 12: Citation

- Footprint (electronics). (2019, August 15). Retrieved August 25, 2020, from https://en.wikipedia.org/wiki/Footprint_(electron...

- Rene_Poschl. (2019, January 13). What is the difference between footprints and symbols? Retrieved August 25, 2020, from mhttps://forum.kicad.info/t/what-is-the-difference-between-footprints-and-symbols/8900

- KiCad EDA. (2020, May 20). Retrieved August 25, 2020, from https://kicad-pcb.org/