Outlines and Key Pins

The component outline and location of the key pin are important visual cues for the operators who mount components on a PCB. This is especially true for polarized components with a symmetrical footprint.

Outlines

Component outlines typically follow one of four patterns:

  • Body tightly encloses the component body
  • Lead-to-lead encloses the component body and all component leads
  • Footprint tightly encloses all of the component pads
  • Courtyard encloses the footprint and the component body

By default, Footprint outlines are created, though this may be overridden by pressing the Ctrl key to create a Body outline. The procedure is:

  1. Double-click on a component in the component list to select it and make it visible in the viewer.
  2. Left-click and draw a rectangle around all of the component pads. A Footprint outline (which tightly encloses the selected pads) is created.
  3. If you press Ctrl when drawing, then instead the drawn rectangle becomes the Body outline.
  4. The outline will be applied to all instances of the selected component.

Note: If a component pad (from the originally imported Gerber data) is drawn (as one or more wide lines/arcs) rather than flashed (as a single shape object) then it will not be identified as a pad in the above procedure. In cases where no pads are found within the selection rectangle, the selection rectangle is used to define a Body outline.

Right-click on a component or component instance to delete it's outline. If an instance is chosen, then only that instance's outline will be deleted. If a component is chosen then the outline will be deleted from all instances of that component.

Key pins

The key pin of a component is pin 1, pin A1, Cathode or Plus. Marking the location of the key pin gives operators a reliable visual reference to the component rotation. This is especially important for PnP components, to help insure that the specified rotation is correct when programming the automatic placement machine.

IPC-7351 specifies the most commonly used definition of component orientation. For an unrotated component, when viewed from above, the key pin is at the left (for 2-pin components). For multi-pin components it is near the upper left corner (or upper center) of the component outline.

To mark the key pin of a component, do the following:

  1. Double-click on a component in the component list to select it and make it visible in the viewer.
  2. Left-click and draw a rectangle around the pad for pin 1 (or A1 or Cathode or Plus).
  3. The key pin will be marked for all instances of the selected component.

Note: If a component pad (from the originally imported Gerber data) is drawn (as one or more wide lines/arcs) rather than flashed (as a single shape object) then it will not be identified as a pad in the above procedure. In cases where no pads are found within the selection rectangle, the (center of the) selection rectangle is used.

Right-click on a component or component instance to delete it's key pin. If an instance is chosen, then only that instance's key pin will be deleted. If a component is chosen then the key pin will be deleted from all instances of that component.