Study Of Working Electrolyte Of Medium Voltage Large Capacitance Wet Tantalum Capacitors

The main content of this project is to study the working electrolyte for medium voltage, large capacitance, low ESR wet tantalum capacitors.The ion distribution at the surface that the electrolyte contacts with the anode dielectric oxide film and at the surface that the electrolyte contacts with the cathode metal was analyzed, and the factors that affect the broken voltage of electrolyte were studied. Cathode capacitance theory, depolarizing theory, and double electronic layer theory of the electrolyte were used during the study.Conductance of working electrolyte is a very important factor that affects the performance of capacitor. It should be mainly considered to increase the conductance of working electrolyte during the studying process, improving its mending ability for the dielectric film, and increasing its boiling point, decreasing its saturation steam pressure, in order to improve the electrical performance of the capacitor roundly.According to the cathode capacitance theory, depolarizing theory, and double electronic layer theory, Adding some appropriate content of depolarizer into electrolyte can decrease the distance of the double electronic layer and increase the fact area of cathode polar. On the other hand, the produce of hydrogen was prevented by depolarizer, which is beneficial to decrease the inner working press of the tantalum capacitors, and to increase its reliability and life-time. Meanwhile, increasing the specific conductance of the electrolyte can help to decrease ESR and tgδof capacitor.Depending on above theory, experiments were performed to select elementary formula, and then 100V/100μF tantalum capacitors were assembled with it. Their performances were measured at room temperature, high and low temperature and high frequency after aging process, and then 1000h high temperature burden test were carried out. The performances turned out to be very good, and satisfied the requirement of the project.