Effect Factors and Modification Measurements of the Leakage Current of
Polypyrrole Aluminum Electrolytic CapacitorsXu Youlong,Wang Jie,Qin Jiwei
(Key Lab. for Physical Electronics and Devices of the Ministry of Education,Xi'an Jiaotong University,Xi'an 710049,China)
Abstract: Polypyrrole aluminum electrolytic capacitors were made by electrochemically depositing polypyrrole on the surface of etched and formed aluminum foils. During the polypyrrole electropolymerization processes, the capillarity of polymerization solutions makes some tiny polypyrrole electrically conducting passages form between the cathode and anode of this capacitor. Furthermore, polymerization solutions corrode the dielectric anode oxide of the capaci-tor. The two cases are intrinsic factors for increasing the leakage current of polypyrrole aluminum electrolytic capacitors. It was found experimentally that coating silicon rubber and shortening the polymerization time could significantly decrease the leakage current, so as to correspondingly improve the frequency characteristics of capacitance and dissipation factor of the capacitor. The thermogravimetric and differential thermal analysis of the unsealed samples in the air revealed that the sealing process is very important to retain a long period stability.
Keywords: polypyrrole;aluminum solid electrolytic capacitor;leakage current