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How Do I Change the Route Width in Altium Designer?

Published in Altium Routing 3 mins read

To change the route width while routing in Altium Designer, you can use keyboard shortcuts or manually adjust settings. Here's how:

Using Keyboard Shortcuts (During Interactive Routing)

  • Press the 3 key: This is the quickest way to cycle through pre-defined track width options. Altium Designer will switch between the minimum, preferred, and maximum width values as specified in your design rules. It will also toggle to User Choice.

  • Press Shift + W: This opens the "Choose Width" dialog. Here, you can select from a predefined list of user widths or directly enter a specific width value in the "User Width" field. This allows you to use custom track widths beyond those specified in your design rules.

Adjusting Widths Via Design Rules

While not directly changing the width during routing, defining appropriate design rules is crucial for controlling available widths.

  1. Access the PCB Rules and Constraints Editor: Go to Design > Rules.

  2. Navigate to Routing Width Rule: In the "PCB Rules and Constraints Editor" dialog, expand the "Design Rules" section, then expand "Routing", and select "Width".

  3. Configure Width Constraints: Create a new rule or modify an existing one. Within the rule, you can define:

    • Minimum Width: The smallest allowed track width.
    • Preferred Width: The default track width that Altium will try to use.
    • Maximum Width: The largest allowed track width.

  4. Specify Rule Scope (Important): Ensure the rule targets the specific nets, layers, or object types you want it to apply to. Use the "Where the Object Matches" section to define the rule's scope using queries (e.g., InNet('PowerNet')). This is critical for applying different width rules to different parts of your board.

Example Scenario

Let's say you need a wider trace for a power net.

  1. Create a new "Width" rule (as described above).
  2. In the rule's properties, set the "Minimum Width" to 0.5mm, the "Preferred Width" to 1.0mm, and the "Maximum Width" to 1.5mm.
  3. In the "Where the Object Matches" section (under "Full Query"), enter InNet('PowerNet'). This ensures the rule only applies to tracks on the "PowerNet" net.
  4. Now, when routing on the "PowerNet" net, pressing the 3 key will cycle through 0.5mm, 1.0mm, 1.5mm, and your last used user width. Pressing Shift + W will allow you to enter a specific user-defined width if none of the predefined values are suitable, but will still check the width againt the min/max design rules.

Summary

Changing track width in Altium Designer during routing is primarily done using the 3 or Shift + W keys. Effective use of design rules to predefine available widths is also critical for ensuring proper track sizing throughout your design and adherence to your PCB design requirements.

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