In a package design, designers often need to perform degassing. This is typically done at the end of the design process before sending the design to the manufacturer.
Degassing is a process where you perforate power planes, voltage planes, and filled shapes in your design. Degassing holes let the gas escape from beneath the metal during manufacturing of the substrate. The perforations or holes for degassing are generally small, having a specified size and shape, and are spaced regularly across the surface of the plane. If the degassing process is not done, it may result in the formation of gas bubbles under the metal, which may cause the surface of the metal to become uneven. After you degas the design, it is recommended to perform electrical verification.
Allegro X APD has degassing features that allow users to automate the process and place holes in the entire shape.
In today’s topic, we will talk about how to avoid adding degassing holes on a particular shape.
Sometimes, a designer may need to avoid adding degassing holes to a particular shape on a layer. All other shapes on the layer can have degassing holes but not this shape. Using the Layer Based Degassing Parameters option, the designer can set the degassing parameters for all shapes on the layer. Now, the designer would like to defer adding degassing holes for this particular shape.
You may wonder if there is an easy way to achieve this. We will now see how this can be done with the tool.
Once the degassing parameters are set, performing Display > Element on any of the shapes on that layer will show the degassing parameters set.
You can apply the Degas_Not_Allowed property to a shape to specify that degassing should not be performed on this shape, even if the degassing requirements are met. Select the shape and add the property as shown below.
Switch to Shape Edit application mode (Setup > Application mode > Shape Edit) and window-select all shapes on the layer. Then, right-click and select Deferred Degassing > All Off.
Now, all shapes on the layer will have degassing holes except for the shape which has the Degas_Not_Allowed property attached to it.