Applied Parameters: None
This command is used to teardrop selected pads on routing (signal) layers in the current document. Teardropping pads is a common technique for guarding against drill breakout during the board fabrication phase.
This command can be accessed from the CAMtastic Editor by:
- Choosing the Tools » Teardrops command from the main menus.
- Clicking the button, on the Fabrication Tools drop-down () of the Utilities toolbar.
First, ensure that the routing (signal) layers that you wish to add teardropped pads to, are turned ON in the Layers list of the CAMtastic panel.
After launching the command, the cursor will change to a small square and you will be prompted to select the pads you wish to teardrop. Simply position the cursor over individual pads and click to add them to the selection, or use one of the many selection tools available. After all pads that you wish to teardrop are selected, right-click. The Add Teardrops dialog appears.
The left half of the dialog allows you to define the style of teardropping you wish to apply - either Pad or Line. The Pad style teardrop will place a pad, half the size of the original pad, at the trace/pad intersection. The Line style teardrop will place two lines (tangential to the pad) to fill in the trace/pad intersection. When using the Line style, you can specify a Line Offset Factor, which controls the length of the teardrop.
The right half of the dialog allows you to define and apply various clearance checks. Define these constraints as required. By default, each is set to 5mil.
The Inflate Pads/Vias bounding Rect By field is used as a method of speeding up the teardropping process. By inflating the bounding rectangle of a pad, you can narrow down the number of traces to be considered for teardropping to only those that touch the inflated boundary. Think of this as a coarse check, followed by the fine check of those traces that are left, to determine if they truly connect with the pad or not. The default setting is 25mil/side.
After defining the teardrop style and clearance checks as required, clicking OK will proceed to add teardrops to all selected pads. If placing a teardrop would result in violation of one or more checks, a pad will not be teardropped.
Continue selecting further pads to be teardropped, or press Esc to exit.
- In order to apply the clearance constraint options, you must have extracted the netlist for the current document, before using the teardropping command.
- A pad will only be teardropped if it has at least one trace connecting to it.
- When teardropping pads, the effect of the inflated bounding rectangle will only be seen for pads that are grouped in a particular area. If pads are far apart in the design, the bounding rectangle used in the coarse teardropping check will be that of the union of individually selected pads, and therefore could extend to include the whole design, and slow down the process.
- It is not advisable to teardrop pads in both your PCB Editing tool and the CAMtastic Editor. The results for trace/pad intersections would be less than desirable.