Converting Pads to Planes

Pads above a certain fraction of the design bounding box area are automatically converted to planes. This fraction can be set using the SIWAVE_PAD_CONVERSION_FACTOR environment variable. The default value is 500. So if the bounding box area is 60E+3 mm2, all pads with area more than 120 mm2 (== 60E+3/500) will be modeled as planes. In addition, SIwave automatically identifies pads overlapping plane geometry, converts these pads into planes (irrespective of their size) and unites them with the overlapping plane(s). The automatic conversion of pads to planes is done only during solver input file generation, with no changes to the layout (the geometry in the Modeling workspace does not change).

To manually select pads in the Modeling workspace and convert them into planes:

  1. Select the pad.
  2. Click Tools. From the Transformation Tools area, click Convert Pads to Planes.

    3. The pads are converted to planes and the layout is changed.

Small circular pads are better off not being modeled as planes. The solver is able to accurately compute capacitance between such pads and any surrounding planes when they are modeled implicitly. Larger pads, especially those that are non-circular, result in improved accuracy when represented as planes.