Changing trace width in Altium Designer is a fundamental task you'll perform frequently, and there are several straightforward methods depending on whether you're currently routing, about to route, or modifying existing traces.
You can change trace width in Altium Designer either before routing, while routing, or after routing, primarily by adjusting settings in the Properties panel or through design rules.
Here's a breakdown of the common methods:
Method 1: Changing Width While Routing
This is perhaps the most dynamic way to adjust width on the fly.
- Interactive Routing: When you are actively routing a trace using the interactive routing tool (
Place > Interactive Routing), you can change the width as you go. - Press the Tab Key: During interactive routing, press the Tab key. This action will pause the routing process and open the Properties panel.
- Adjust Width: In the Properties panel that appears, locate the Width setting under the Net Information section. Here, you can select or type a new width value.
- Resume Routing: Once you've set the desired width, click anywhere outside the panel or press
Tabagain to resume routing with the new width.
Important Note: As highlighted by the reference, when using the Tab key during interactive routing, the width values available or that you can enter are constrained by the Min Width and Max Width settings defined in your active Design Rules for that net or layer.
Method 2: Changing Width Before Routing
You can set the trace width before you even start placing a trace.
- Access Properties Panel: With no objects currently selected in the PCB editor, open the Properties panel (typically located on the right side of the screen, or use
View > Panels > Properties). - Set Interactive Routing Options: In the Properties panel, look for the Interactive Routing section. Here, you can set the preferred Width that will be used for new traces placed subsequently using the interactive routing tool.
- Choose Layer/Net: You might also need to ensure the correct layer and net are active or selected depending on your setup.
Method 3: Changing Width After Routing
To modify the width of traces that have already been placed:
- Select the Trace(s): Click on the specific trace segment or multiple trace segments you want to change. You can
Shift+Clickto select multiple, or use selection tools. - Use Properties Panel: With the trace(s) selected, the Properties panel will update to show the properties of the selected objects.
- Adjust Width: Find the Width setting in the Properties panel and enter or select the new desired width. All selected trace segments will update.
- Find Similar Objects: For changing many traces with specific criteria, you can use
Edit > Select > Find Similar Objects. This tool allows you to select traces based on criteria like their current width, layer, or net, and then modify all selected traces simultaneously via the Inspector panel (View > Panels > Inspector).
Understanding Design Rules
Design Rules are crucial as they govern many aspects of your PCB design, including trace widths.
- Access Design Rules: Go to
Design > Rules. - Width Rules: Navigate to the Routing > Width section.
- Define Constraints: Here you can define different width constraints (Min Width, Preferred Width, Max Width) for various nets, net classes, or layers.
- Impact: These rules are not just for checking (via Online DRC and Batch DRC); they actively influence interactive routing. The Min Width and Max Width settings define the permissible range when you use the Tab key to change width during routing. Your preferred width is often the default used when you start routing, but you can deviate within the min/max range using the Tab key.
Summary of Methods
| Method | When to Use | How to Access/Execute | Key Feature/Constraint |
|---|---|---|---|
| During Routing | Placing a new trace | Press Tab, change Width in Properties panel |
Limited by Min/Max Width Design Rules |
| Before Routing | Setting default width | Properties panel (no objects selected), Interactive Routing | Sets the starting width for new traces |
| After Routing | Modifying existing trace | Select trace(s), change Width in Properties or Inspector | Affects selected segments; overrides rule compliance (check with DRC) |
| Via Design Rules | Setting project standards | Design > Rules > Routing > Width |
Defines Min/Preferred/Max limits; enforced by DRC |
By utilizing these methods, you can efficiently manage trace widths throughout your Altium Designer projects, ensuring your board meets both electrical requirements and manufacturing constraints.
