Research On Ultra-Low ESR Solid Tantalum Electrolytic Capacitors Cathode Technology

Solid tantalum electrolytic capacitors with low equivalent series resistance, small volume, large capacity, low leakage, high reliability, long life and other advantages are widely used in various circuits.As the electronic equipment to develop in the direction of miniaturization, high frequency, tantalum capacitor to low equivalent series resistance, small volume, large capacity, low leakage current, etc.With the frequencies increasing of military equipment, the requirement for higher frequency ESR of Solid Tantalum Electrolytic Capacitors has also enhanced. For Solid Tantalum Electrolytic Capacitors, the cathode Manganese dioxide fabrication technologies and its material properties would largely affect the performance of Solid Tantalum Electrolytic Capacitors. Low pressure, high capacity and high frequency Tantalum Electrolytic Capacitors has always been difficult process in fabrication. In this thesis, we studied the sealed Solid Tantalum Electrolytic Capacitors 6.3V 330μF, The main research contents and results, including:l.Low concentration of nitric acid manganese has good permeability, Study of Impregnation very low concentrations 1.08g/mL Manganese nitrate solution for its effects on all electric parameters to find the best impregnation numbers, For the experimental samples, dipping 4 times the best effect.2. Study the water vapors inside oven and changes on capacitor electric parameters. For current devices and samples, when the oven water vapor pressure is 0.05 Mpa, Various electrical parameters are better capacitor, especially the capacitor ESR value is the best, and the stability of the high and low temperature is better.3.Study adding different ratio of Ammonium nitrate into Manganese nitrate solution for their effects on electric parameters, especially the loss and ESR are largely affected. After comparison, when the ratio is 4%, the smallest ESR with better stability.4.Study the concentration of enhancing solution of its effects on capacitor electric parameters, and find the best ratio of enhancing solution.5.By dipping a very low concentration manganese nitrate solution, thermal decomposition of water environment, adding ammonium nitrate and nitric acid manganese solution to strengthen the combination of liquid concentration, compared with the original process experiment, capacitor ESR fell by around 40%, without causing the defect of other electrical parameters.6.With the optimization of choosing Graphite,The solid content of graphite and silver paste, and dipping height and curing process of capacitor ESR, when the graphite solid content is 15%, silver slurry solid content is 72%, graphite, silver paste dipping height is respectively:90%～95% and 90%, curing conditions are:150℃/60 min and 170℃/90 min, improve the effect of the derivation of the cathode, reduces the ESR.7.Olding,foeming,capsule of solid tantalum capacitors encapsulation and measure all of the production process such as put forward the optimization scheme,maximum limit reduces the ESR.Based on the studies, we propose a new cathode fabrication method, which successfully lower the ESR value of Solid Tantalum Electrolytic Capacitors.