Allegro PCB Editor offers drafting and dimensioning features that support electronic design automation (EDA) industry standards that enable you to specify the dimensions of every feature on a board created from the product. This feature gives you greater control over the manufacturing release of your design. The layout editor also enables you to customize the dimensioning process to conform to the manufacturing requirements of your site. Drafting and dimensioning normally occurs in the later stages of the design process.
From the app note mentioned later in this blog, you will learn how to modify several types of dimensions and control their appearance by setting up dimensioning parameters or by editing individual dimensions. In SPB16.5 version of symbol editor and PCB Editor, when you create a dimension, it is saved as a database object. As a result, the dimension becomes associated with the object and gets edited and deleted with the object.
You can watch the video demonstration on dimensioning associability here: Associative Dimensioning
NOTE: If a symbol that has non-associative dimensions in the symbol file is placed on the board, the dimensions remain non-associative on the board.
Enabling New Dimensioning Environment
To invoke the dimensioning environment in SPB 16.5, use any one of the following:
- Choose Manufacture - Dimension Environment
- Run the dimension edit command (Use the toolbar icon)
After invoking the dimensioning environment, right-click to see the various dimensioning commands available in Allegro PCB Editor.
Migrating Dimensions into SPB16.5
When migrating a board with dimensions into SPB16.5, you have the following options:
- The dimensions added in the previous release remain inactive or non-associated with the objects. They cannot be edited or moved. You can use them as they are.
- Remove the old dimensions using the delete command and re-create them using the new dimension environment.
- Add new dimensions to the design.
Dimensioning Commands in SPB16.5
1. Moving dimensions to another class/subclass
To move an existing dimension to another class/subclass, use the Z- Move Dimensions command.
The valid class-subclasses are:
- Board Geometry
o Dimension
o Assembly notes
o User-defined subclass
- Drawing Format
o User-defined subclass
- Manufacturing
o User-defined subclass
2. Displaying dimension Information
To see dimension-related information, use the Show Dimension command.
This command opens the "show element" form.
3. Modifying dimensions globally
By initiating the Parameters command, you can set the global parameters for dimensioning to the existing as well as future dimensions. This command displays the Dimensioning Parameters dialog.
In the example below, the linear dimension settings are changed globally.
NOTE: If you change the parameters displayed in blue, these changes will be applied to future dimensions only.
4. Modifying instance-specific dimensions
You can also change the instance-specific parameters using the Instance Parameters command. The parameters displayed in blue can be set to a value other than the global parameter for that particular dimension.
For example, dual dimension is added below the primary linear dimension.
NOTE: The instance-specific setting initially shown is the last setting for the selected dimension.
Similarly, you can add tolerance to any dimensioning instance.
5. Deleting Dimensions
To delete dimensions, choose the Delete dimensions command and select dimension. This command dissociates the selected dimensions from the object and removes them from the database.
6. Locking and unlocking dimensions
To fix/unfix the location of dimension text or leader end-point, use the Lock dimensions and Unlock dimensions commands.
7. Moving and changing dimension text
To move the dimension text location, use the Move text command. This command lets you move and place the dimension text to a new location. Similarly, to edit the dimension text, use the Change text command. You can change the text string by entering the new value in the Options tab.
Watch an elaborative video on dimensioning in Allegro PCB editor at:
Refer to the app note here for the detailed step-by-step procedures on the Dimensioning functionality, as well as various other aspects that are not covered in this blog.
Note: The above link can only be accessed by Cadence customers who have valid login credentials for Cadence Online Support (http://support.cadence.com/).
Naveen Konchada
Cadence Customer Support