Research On Solid Tantalum Capacitors Dielectric Oxide Film-Ta₂O₅ 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 improvement of military equipment line voltage, resistance and reliability of tantalumcapacitors is also put forward higher requirements. For solid tantalum electrolytic capacitor, Ta2O5 determines the quality of dielectric oxide filmresistance and reliability of tantalum capacitors. Tantalum solid capacitors for high pressure is always a difficult problem in the process of production. This article attempts to study the whole sealing solid tantalum electrolytic capacitor as the test samples, the main research contents and resu include:1、the crystallization phenomenon is the main reason of Ta2O5 dielectric oxide film forming quality, specially about the effect of crystallization and crystallization mechanism of capacitor performance.2、research the effects of oxygen content on the dielectric oxide film formed by Ta2O5 Oxygen is one of the main factors affecting the tantalum anode oxide film is formed, which has a direct impact on the electrical properties of tantalum electrolytic capacitor. Should be strictly controlled in Ta powder impurity oxygen content, help to improve the quality and performance of tantalum electrolytic capacitor.3、studied the effect of citric acid is formed in the form of adding different proportion of Ta2O5 solution in the dielectric oxide film. The experimental results show that adding a certain amount of citric acid is formed in the liquid, can effectively improve the quality of Ta2O5 dielectric oxide film formation, reduce the failure rate of earlytantalum capacitor, and improve the reliability of tantalum capacitors.4、The effects of concentration of phosphoric acid in the formation of liquid dielectric oxide film formedon Ta2O5, PO43- and a small amount of liquid in the form attached to the dielectric oxide film,attached to the PO43- can effectively prevent the migration of oxygen ion and electron, decreases the leakage current at the end of the phosphate concentration increased, will increase the amount ofattached to PO43-, to reduce the leakage current.5、Effect of temperature on the formation of the formation of Ta2O5 dielectric oxide film was studied in the process of formation, anodic tantalum core itself will generate heat, when the forming voltage is very high, the tantalum core long time in high strength and high temperature environment, the crystallization will accelerate Ta2O5 dielectric oxide film, seriously affecting the performance of tantalum capacitors.6、To study the effects of current density and reaction time on the formation of Ta2O5 dielectric film,the current density is too large, will cause the core to heat of crystallization, the current density is too small, can lead to the formation of time, form a long time will lead to the production of High-pressureCrystallization, tantalum capacitors, initially with a current form, when the formation to a certain extentafter gradually reduce the current, can prevent crystallization. Because of the pressure of time and pressure of tantalum capacitors for a long time, should be appropriate to reduce the pressure.7、Effects of voltage on Ta2O5 dielectric oxide film formed on the formation of voltage selection needs to consider several factors, for special products, the formation of the selection of voltage should be targeted.8、After the formation of heat treatment and compensation effect on the formation of Ta2O5 dielectricfilm were studied, the heat treatment after forming can eliminate the defects of Ta2O5 dielectric oxide film, the Ta2O5 film changes of beta Ta2O5, crystallization, film directed, and makes the surface wettability of better. The formation of oxide film after repair and fill thickness, but must adjust patchformation time, time is too short to reach the degree of restoration of the ideal, time is too long will cause crystallization.9、Two strengthen the anode of tantalum block, two form can strengthen the Ta2O5 dielectric oxide film, reduce the stress on the capacitor damage, improve the electrical properties of capacitor, improve the voltage of capacitor.Through the above research, combining with other optimization process each link, effectively improve the quality of Ta2O5 dielectric film, improves the pressure resistance and reliability of solid tantalumcapacitors.