PCB design is a critical stage in electronics development, directly influencing manufacturing quality, assembly efficiency, and product performance. Every dimension, clearance, and layout parameter established during the design process affects the final printed circuit board. As project requirements evolve, designers often need to adjust board dimensions to accommodate new components, optimize mechanical fit, or improve manufacturability.
For engineers using Altium Designer, understanding how to change PCB board size efficiently is an essential skill. Whether you are resizing a simple two-layer board or modifying a complex multilayer design, Altium provides several tools that allow precise control over board dimensions and shape.
What are the Key Points in Altium about PCB Size
Before making any modifications to the board outline, it is important to understand how Altium manages PCB dimensions and board geometry.
Board Shape and Board Regions
The board shape defines the physical boundary of the PCB. Altium treats the board outline as a dedicated design object that determines the manufacturing limits of the board.
All components, copper traces, vias, and mechanical features should remain within the board boundary. Objects placed outside the board outline may generate design rule violations or manufacturing issues.
Board outlines can be created using:
Straight lines
Arcs
Circles
Polygons
Custom-drawn shapes
As project requirements change, designers frequently need to resize or reshape the board to meet enclosure constraints or optimize layout efficiency.
Design Objects and Component Placement
Altium includes extensive component libraries containing footprints, symbols, and mechanical objects. During board resizing, component placement and routing must be carefully reviewed to ensure adequate spacing and maintain electrical integrity.
A board size modification can affect:
Component clearances
Signal routing
Mounting hole locations
Mechanical fit
Manufacturing tolerances
Proper planning helps avoid unnecessary redesign work later in the project.
Why Change PCB Board Size?
There are several common reasons engineers modify PCB dimensions during development:
Accommodating additional components
Reducing product size
Matching enclosure requirements
Improving thermal performance
Optimizing manufacturing costs
Meeting mechanical design specifications
Enhancing signal routing efficiency
Regardless of the reason, any board size adjustment should be validated carefully before production.
Step-by-Step Guide to Changing PCB Board Size in Altium
Step 1: Save a Backup of the Existing Design
Before making any modifications, create a backup copy of the current PCB project.
Navigate to:
File → Save As
Save the design under a new file name or project version. This ensures the original layout remains available if unexpected issues arise during editing.
Step 2: Configure Units, Origin, and Grid Settings
Accurate board editing begins with proper measurement settings.
Open the PCB document and configure:
Design units (millimeters or mils)
Board origin
Grid spacing
Snap settings
The origin point serves as the reference location for dimensions and coordinates. A properly configured grid makes it easier to align board edges and maintain precise geometry during resizing.
Fine grid settings are particularly useful when working with compact or high-density PCB layouts.
Step 3: Enter Board Planning Mode
To modify the board outline, switch from standard editing mode to Board Planning Mode.
Navigate to:
View → Board Planning Mode
This mode allows direct access to the board shape and mechanical outline without affecting other design elements.
Carefully identify the area that requires modification before proceeding.
Step 4: Modify the Board Shape
Altium offers multiple methods for changing PCB dimensions.
Adjust Existing Edges
For simple size changes:
Select the board edge.
Click and drag the edge to the desired position.
Release the mouse to apply the new dimension.
This method is ideal for minor length or width adjustments.
Add New Vertices
For more complex shapes:
Hold Ctrl and click on the board outline.
Insert additional vertices.
Drag the vertices to create the desired geometry.
This approach provides greater flexibility for custom board designs.
Modify Corners
Corners can be adjusted using different styles, including:
90-degree corners
45-degree corners
Rounded corners
Custom angles
Press Shift + Spacebar while editing to cycle through available corner modes.
Redefine the Entire Board Shape
For major changes:
Navigate to:
Design → Redefine Board Shape
The cursor will change to drawing mode, allowing you to create an entirely new board outline.
Click sequential points around the desired shape and complete the outline to generate a new board boundary.
Extend Existing Shapes
If you only need to add sections to the current board outline:
Navigate to:
Design → Modify Board Shape
This feature combines new geometry with the existing board boundary, making it useful for adding tabs, extensions, or custom mechanical features.
Step 5: Verify and Validate the Design
After resizing the PCB, perform a thorough review of the layout.
Key areas to inspect include:
Component-to-edge clearance
Trace routing integrity
Mounting hole locations
Copper pours
Keep-out regions
Mechanical layer alignment
Any board modification can introduce unintended design conflicts that should be identified before manufacturing.
Step 6: Run Design Rule Check (DRC)
Altium provides a comprehensive Design Rule Check (DRC) system that automatically identifies potential design violations.
Navigate to:
Tools → Design Rule Check
Review all reported issues and correct any errors related to:
Clearances
Routing constraints
Component placement
Manufacturing requirements
Once the design passes validation, save the updated PCB file and generate the required manufacturing outputs.
Best Practices When Resizing a PCB in Altium
To ensure successful modifications, consider the following recommendations:
Always work from a backup copy of the project.
Use fine grid settings for precise adjustments.
Maintain adequate clearance between components and board edges.
Verify that all board outline loops are fully closed.
Check for hidden design objects before finalizing changes.
Use chamfered or rounded corners when required for manufacturing.
Review mechanical constraints after every modification.
Following these practices can significantly reduce design errors and production risks.
Conclusion
PCB dimensions play a vital role in product functionality, mechanical compatibility, and manufacturing success. Even minor changes to board size can affect component placement, signal routing, and assembly performance.
Altium Designer provides powerful tools for modifying board outlines, whether you need to make simple edge adjustments or completely redefine the PCB shape. By understanding the proper workflow and validating every change through design rule checks, engineers can confidently modify board dimensions while maintaining design integrity.
As modern electronic products continue to become smaller and more complex, mastering how to change PCB board size in Altium remains an essential skill for PCB designers and hardware engineers.
