Dielectric Breakdown Prediction
XF can help predict locations at risk of suffering dielectric breakdown.
An electrostatic discharge (ESD) is the sudden flow of current between two electrically charged objects caused by the breakdown of the dielectric(s) separating them (i.e., dielectric breakdown). If the dielectric strength of a material is known, then locations at risk of experiencing dielectric breakdown can be determined by an XF simulation.
Dielectric strength is defined as the maximum electric field a material can withstand without losing its insulating properties and can be defined for electric materials using XF’s material editor. Materials are assigned a dielectric strength of infinity by default and will not be monitored for dielectric breakdown during an FDTD simulation. Entering a finite dielectric strength in V/m allows XF to monitor transient field values encountered by the material during time-stepping and check for potential dielectric breakdown.
Dielectric Breakdown Sensor
To monitor the FDTD domain for dielectric breakdown, a near field dielectric breakdown sensor can be created. The bounds of this sensor may be defined to encompass the entire simulation domain, the bounding box of the geometry, or to any sub-volume desired by the user. The freespace dielectric strength defines the dielectric strength for all freespace cell edges in the simulation domain and is assigned a default value of 3.0 MV/m corresponding to the dielectric strength of air at sea level.
Dielectric Breakdown Ratio
FDTD cell edges which exceeded their dielectric strength during a simulation can be examined by choosing the dielectric breakdown sensor and dielectric breakdown ratio result type from XF’s results browser. The dielectric breakdown ratio of a cell edge is defined as the maximum electric field encountered during the simulation divided by the cell edge’s dielectric strength. The moment in time that a cell edge exceeded its dielectric strength can be determined and the cell with the highest dielectric breakdown ratio can easily be located using a convenient “zoom to maximum” button.