Altium Designer, a widely used Electronic Design Automation (EDA) software, offers a plethora of features that enhance circuit board design and manufacturing. One such feature is the ability to define polygon clearances, which is essential for ensuring proper spacing between conductive and non-conductive areas on a PCB. This article aims to guide you through the process of changing polygon clearances in Altium Designer, providing a comprehensive understanding of the procedure and its significance.
Understanding Polygon Clearances in Altium Designer
Polygon clearances in Altium Designer, often referred to as "keepout distances," are crucial parameters that define the minimum allowed distance between a polygon pour and any other object on the PCB layout. These objects can include copper traces, components, vias, or other polygons. Proper polygon clearances are essential for preventing shorts, ensuring proper signal integrity, and facilitating manufacturability.
Significance of Polygon Clearances
- Preventing Shorts: Adequate polygon clearances guarantee that conductive areas remain isolated from each other, preventing unintentional electrical connections or shorts.
- Signal Integrity: Maintaining appropriate distances between polygons and traces helps preserve signal quality by minimizing crosstalk and other interference.
- Manufacturability: Defined polygon clearances ensure that the PCB can be manufactured accurately and reliably, avoiding fabrication issues due to insufficient spacing.
How to Change Polygon Clearances in Altium Designer
Modifying polygon clearances in Altium Designer is a straightforward process that involves adjusting the "Keepout" property of the polygon pour. This property controls the distance between the polygon edge and any surrounding objects. Follow these steps to change polygon clearances:
- Open the PCB Layout: Start by opening the PCB layout file in Altium Designer.
- Select the Polygon Pour: Use the selection tool to highlight the polygon pour you wish to modify.
- Access the Properties Panel: The "Properties" panel is typically located on the right side of the Altium Designer window. Click on the "Properties" tab to reveal the panel.
- Locate the "Keepout" Property: Within the "Properties" panel, scroll down until you find the "Keepout" property.
- Modify the Keepout Value: The "Keepout" property usually displays the current clearance value. You can change this value by entering a new number in the designated field.
- Apply Changes: After adjusting the "Keepout" value, click "Apply" or "OK" to confirm the changes.
Additional Tips for Modifying Polygon Clearances
- Units of Measurement: Ensure that you understand the units of measurement for the "Keepout" property (e.g., millimeters, mils).
- Global vs. Local Clearances: Altium Designer allows you to set global polygon clearances that apply to all pours or define specific clearances for individual polygons.
- Automatic Clearance Calculation: Altium Designer also offers an automatic clearance calculation feature that can help you determine appropriate clearance values based on the selected trace width and spacing rules.
Best Practices for Setting Polygon Clearances
- Consult Design Rules: Always refer to your PCB design rules for guidance on recommended polygon clearances based on your specific project requirements.
- Consider Manufacturing Capabilities: Take into account the capabilities of the PCB manufacturer when setting polygon clearances. Tight clearances might be difficult to manufacture accurately.
- Review and Verify: After modifying polygon clearances, conduct a thorough review of your PCB layout to ensure that all spacing requirements are met and that there are no potential conflicts.
Conclusion
Changing polygon clearances in Altium Designer is a fundamental step in PCB design, ensuring proper spacing between conductive and non-conductive areas. By understanding the process and utilizing the appropriate settings, you can optimize your PCB layout for manufacturability, signal integrity, and overall functionality. Remember to consult design rules, consider manufacturing capabilities, and thoroughly review your changes to maintain a robust and reliable PCB design.