PCB Design Rules Setup in KiCAD

By Michael Femiani

Introduction

Before reading this, review Peralta Lab PCB Mill Specs. We will pull information from there to set up PCB design rules in KiCAD. There are a few setting that are recommended above the actual mill capabilities. This knowledge may come in handy if you have a particular component that does not fit into the recommended settings.

Resources

Peralta PCB Mill Specs

Steps:

  1. Open PCB editor

  2. Set grid scale to mils – This will allow us to set the design rules using mils instead of mm.

Figure
Figure

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  1. Setup Design Constraints

File>Board Setup>Design Rules>Constraints

Click file, select Board setup. When the Board Setup window pops up, find the Constraints section under Design rules on the left side of the window.

Default Settings
Default Settings

The window should look like this. These are the setting we will be changing.

Figure
Figure

Updated Settings:

Chance your settings to look like this. See explanation of changes below.

Updated Settings
Updated Settings

  • Minimum clearance – the minimum amount of space between two copper traces.

    • 10 mils – highly recommended. Actual minimum = 6 mils but can cause issues with manufacturing and signal integrity.

  • Min track width – the minimum width of copper traces on your PCB

    • 15 mils. Smaller copper traces may tear up during manufacturing or assembly

  • Min annular ring width – Minimum copper ring around a through hole. When you create your footprints, larger is better but for the design rules we want the minimum allowable.

    • 15 mils.

  • Minimum via diameter – a via is a plated through hole that is used to route a trace from one layer of the board to another.

    • 19.7 mils

  • Minimum Copper to hole clearance – this is the clearance between a copper plane or trace and a through hole annular ring. A Larger clearance helps ensure no shorts during soldering.

    • 10 mils

  • Hole to hole clearance – This is a package parameter called pitch. Pitch is the distance between pins on a component (header, IC, MCU, etc.).

    • 31.5 mils

  • Leave the rest default

  1. Solder Mask Clearance

In the Solder Mask/Paste tab, set the Solder mask clearance to 5 mils. This will ensure that the solder mask does not end up on top of a pad, preventing you from soldering to it.

Figure
Figure

Now you are ready to start designing your PCB. When you want to check you board for any design rules violations, click inspect at the top of the window and select Design Rules Checker.

Click on Run DRC at the bottom right of the window. This will check the PCB design for the rules we assigned and provide a list of errors and warning that need to be fixed.

Figure
Figure