The standard pad object can:
However, there is a huge variety of pad shapes needed for component footprints, and standard pads are not always enough. To create a different shape from those listed above, you must create a custom pad shape.
Custom pad shapes can be created by converting placed Region objects or a closed outline, or directly, by selecting the new Custom Shape entry from the Shape drop-down in the Pad mode of the Properties panel.
To create a custom shape pad by converting regions:
The pad of the custom shape will be created on the layer on which the original pad has been placed.
In some cases (e.g., if the pad shape should be defined according to a component datasheet or using imported data), it can be more convenient to define a custom shape by creating a closed outline. To create a custom shape pad by converting an outline:
The pad of the custom shape will be created on the layer on which the original pad has been placed. Note that the outline objects will remain – you can reuse or remove them.
A pad of a standard shape (round, rectangle, octagon, etc.,) can be converted to a custom shape pad directly from its properties. To do this:
To edit the shape of a custom pad, you can use techniques similar to those when creating a new custom pad shape from scratch.
Select region object(s) or an outline placed and the existing custom shape pad in the design space and select the Add Selected Region to Custom Pad or Create Custom Pad from Selected Outline command. You will be prompted to select a required action: replacing the existing custom pad shape or merging the new shape with the existing one.
Alternatively, use the outline vertices grid in the pad properties or the Edit Shape button to edit the pad shape interactively similar to when defining a custom shape for a pad just converted from a standard shape pad (see above).
The Modify Custom Pad shape command from a custom shape pad's right-click Pad Actions menu is also available. Once the command is launched, the cursor becomes a crosshair. Each time you click, a new vertex is added to the existing pad shape. You can extend the original border outside of the existing shape and/or come back inside the original border to essentially 'remove' an existing area. Use Shift+Spacebar to change placement modes and the Spacebar to switch end cornering modes.
You can also explode a custom shape pad to a region and a standard shape pad by selecting it and choosing the Pad Actions » Explode Custom Pad to Free Primitives command from the pad's right-click menu or the Tools » Convert » Explode Custom Pad to Free Primitives command from the main menus.
When a custom shape pad is placed in a PCB document, thermal relief conductors connecting the pad with a surrounding polygon are placed so they intersect the pad origin. The number of conductors (2 or 4) and their rotation angle (45 or 90 degrees), as well as the width of conductors and the air gap between the pad and polygon, are defined by the applicable Polygon Connect Style design rule.
This behavior can be overridden by enabling the Thermal Relief option in pad properties and clicking the ellipsis button. When the Conductors by Pad Edges option is disabled in the Edit Polygon Connect Style dialog that opens, the thermal reliefs for this pad are placed as described above. When the option is enabled, the thermal relief conductors are placed from the center of each side of the custom pad shape region.
Examples of custom shape pad connections to their surrounding polygons when the Conductors by Pad Edges option is enabled and disabled for these pads are shown in the image below.
To simplify the process of selecting custom shape pads, scoping design rules, etc., the following query keywords are available:
|Custom Shape Pad Type Query||Returns|
|IsCustomShapePad||All pad objects of a custom shape.|
|IsCustomPadShapeOnLayer||All pad objects of a custom shape on the specified layer,
You can also use the PadShape_AllLayers, PadShape_TopLayer, PadShape_BottomLayer, and PadShape_MidLayer<n> keywords with the
'Custom Shape' string to get pads of custom shape on a specific layer. For example, the
PadShape_TopLayer = 'Custom Shape' query returns pad objects with a custom shape on the top layer.
Pads of custom shapes will be exported as pads of the
Custom DCode Shape to Gerber and ODB++ outputs. Custom pad shapes are output in these formats as true contours with arcs.