Chemical Prpcesses During Electrical Breakdown in an Organic Dielectric with Evaporated Thin Electrodes

In capacitors with metallized organic dielectrics electrical breakdown may be of great importance for reliability. In the case of pinholes in the dielectric, the thin electrodes in the surroundings are vaporized within a few μs and therefore the pinholes are insulated. This process is closely associated with gas reactions. The atoms of the dielectric decomposed by the spark plasma are converted by very fast reactions into the components CO and CmHn, the respective concentrations of which determine the deposition of graphite in the metal free insulating areas of the electrodes. In this study the significant features of the conversion processes associated with electrical breakdown are analyzed. The theoretical model comprises the decomposition of the dielectric into atoms by very high energy flux densities of bremsstrahlung of electrons in the spark, gas dynamical phenomena in the forming gaseous phase, and equilibrium reactions between the atoms and the components at very high pressures and temperatures.