Aluminium or tantalum electrolytic capacitors - using dielectric silica layer in addn. to dielectric alumina or tantalum oxide layer

摘要

The capacitor employs a valve metal and the oxide of that metal as a dielectric; and the oxide is covered by a second dielectric which is of SiO2. One pref. capacitor uses a liq. electrolyte and a winding consisting of Al foil coated with dielectric oxide, followed by SiO2, then an insulating foil impregnated with electrolyte, plus a second Al electrode foil. Alternatively, Al foil has an oxide coating, then SiO2 covered by Al foil. A third capacitor uses an anode of sintered Al or Ta, covered by dielectric oxide and then SiO2; in this case a solid electrolyte is used. In all cases, the SiO2 is obtd, via a soln. of an organosilicon cpd. and thermal decompsn. of the cpd. at 150-500 degrees C. The second dielectric of SiO2 covers any faulty zones in the oxide dielectric which is either Al2O3 or Ta2O5.