Footprints are groupings of objects that include one or more objects of type Pad. Footprints are placed in the document as objects of type Device. They are defined and exported via Frame objects.
Oggetti per la definizione dei footprint
The following objects can be used to define a footprint:
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An object Hotspot to specify the origin point, or insertion point, of the footprint.
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Objects of type Reference. It is used to specify the style and position of text that represents the reference of a component.
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Objects of type Value. It is used to specify the style and position of the text that indicates the type of component or the value of the component.
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Objects of type Attribute. Graphic attributes can be used to display the value of internal attributes. See To display the internal attributes of symbols in the drawing.
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Objects of type Pad, Via, Cutout, Courtyard, Copper, Deletion, Keepout.
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Graphic objects of type Line, Curve, Arc, Circle, Ellipse, Rectangle, Shape, Text, Group.
Structure of a footprint page
On pages, footprints are defined via Frame objects. Each footprint will be formed solely by objects that are entirely enclosed within the rectangle of the corresponding frame object.
Layers to include in a footprint page
The page must include the following layers:
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A Library type layer in which to draw Frame objects for defining footprints. All objects on this layer will not be included in the footprint.
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A Top Copper layer in which to display the pads.
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A Pads layer where the pad numbers are displayed.
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A Holes layer in which to display the holes of the pads.
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A Top Pastemask layer to display the areas where the solder paste is to be applied. Generally, the shapes shown on this layer correspond to the SMD pads, or are slightly smaller. You can use graphical objects to add additional areas on this layer.
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A Top Soldermask layer to display areas where the Solder resist should not be applied. Generally, the shapes shown on this layer correspond to those of the pads, or are slightly larger. They create openings in correspondence with the welding areas. You can use graphical objects to add additional areas on this layer.
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A Top Courtyard layer where you draw an object Courtyard to define the footprint profile.
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A Top Legend layer in which to draw the outline of the component to be reported on the PCB. An object Reference and an object Value must also be added to this layer.
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A Top Assembly layer in which to draw the black and white outline of the component and any useful information for the assembly of the component on the PCB.
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A Top Image layer where you draw the graphic image of the component.
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If your footprint should include copper areas, you must also add the Board layer and enable the Create full-page Board option in the layer properties.
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To initialize a footprint page you can load the layer stack "Layer stack for footprint library". |
To create a footprint library
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Create a new Job as described in Create a new Job.
Create a new project for each volume in the library. See Creating a new project in the Job.
In the projects, create a PCB document
for each chapter of the volume.
See Creating a new document.
Create a page in your documents for each topic in the chapter. Choose the Page manager command in the Settings menu to open the Page manager dialog box.
On the pages, open the Layer Setup dialog and load the layer stack "Layer stack for footprint library".
Create the footprint. Do one of the following:
Drawing a Footprint. Use the drawing tools to draw all the objects that make up the footprint. See Drawing a footprint.
Drawing a 3-Tier footprint. With a 3-Tier footprint library, you can meet the different needs arising from component tolerances, the assembly process and the density of components on the board. See Drawing a 3-Tier PCB footprint.
Creating a footprint automatically. For some families of components it is possible to create footprints automatically by specifying the dimensional parameters of the components. See Creating a footprint using the wizard.
Save the Job.