Skip to main content

PCB Footprint Design Guidelines

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • The PCB footprint is the physical interface between the component and the circuit board.

  • The PCB footprint gives the designated locations to solder the components as per the design. 

  • IPC-7351 is the standard that ensures the utmost solder joint quality after the placement of components.

PCB Footprint Design Guidelines

It is important to follow PCB footprint design guidelines, as they ensure the circuit meets design criteria

The PCB footprint is the physical layout that represents the electrical and mechanical components of a board. The footprint comprises the arrangement of the metal pads, vias, through-holes, etc., and plays a critical role in ensuring the electrical and mechanical connections on the board. It is important to follow PCB footprint design guidelines, as they ensure the circuit meets design criteria and works properly. Let’s discuss the PCB footprint design guidelines that you should follow. 

PCB Footprints

A PCB footprint is the physical interface between a component and the circuit board.

The PCB footprint gives the designated locations to solder the components as per the design as well as the physical size of the components, placement location, and associated traces. The PCB is then assembled according to the PCB footprint, also called a land pattern or pad pattern. Through traces and vias, the PCB footprints on a board are interconnected. 

The Various Parts of a PCB Footprint

Parts of PCB Footprint    

Standard Packages and PCB Footprints

For all standard components, footprints are available within the PCB design software library. However, there is a provision to create the PCB footprint by the designer as well. The PCB footprint should match the component in physical dimensions. Otherwise, they will not fit into the pads.      

Creating PCB Footprints

Sometimes designers have to create their own PCB footprints. Imagine you are using a component in your circuit, but could not find the component library in the PCB design software database. This is an example of a time you might have to design your own PCB footprint. Other situations where you might create a PCB footprint include:

  1. When the manufacturer's datasheet does not provide the land pattern.
  2. When you are creating or using sub-assemblies consisting of components such as ICs, passive elements, or even combinations of multiple circuits. 

The Steps to Creating a PCB Footprint

PCB Footprint creation steps

PCB Footprint Design Guidelines

PCB footprint design guidelines detail the arrangement of the pads and the distance between consecutive pads. The PCB footprint should clearly distinguish the component spacing, board edges, mounting holes, etc. Here are some common PCB footprint design guidelines:

  1. Follow the footprint pad guidelines that provide information regarding the pad spacing between surface elements, drill holes, other pads, board edges, etc.

  1. When creating the PCB footprint, create the pad information, component outline at the maximum material width, online silk screen, reference designations, and STEP models.

  1. Make it a point to include accurately sized pads around the component edges. 

  1. For through-hole components, it is necessary to include the location of the hole. 

  1. Make sure you have exact information regarding the component, including the correct specifications, and adhere to the IPC-7351 standard as the base document.

  1. For polarized capacitors, polarity should be marked in the PCB footprint. Similarly, for components such as diodes, SCRs, and MOSFETs, the PCB land pattern should indicate the pin details.

  1. It is important to mark pin-1 in the quad and DIP IC packages.

  1. Include all the required data. Neglecting some of the attributes while creating a PCB footprint may lead to obsolete PCB boards.

By following the above PCB footprint design guidelines, it is possible to shorten the time to create a PCB board. Cadence’s OrCAD software offers easy PCB footprint creation. Leading electronics providers rely on Cadence products to optimize power, space, and energy needs for a wide variety of market applications. If you’re looking to learn more about our innovative solutions, talk to our team of experts or subscribe to our YouTube channel.