The Preparation Technology Of Tantalum Powder For High CV Tantalum Capacitor

As tantalum capacitor has good qualities such as miniaturization, high capacity, high efficiency and high stability, reliability, long service life etc., it has been widely used in electrical, communications, automotive, military, aerospace and other fields. Tantalum powder is an important material of tantalum capacitor. This thesis mainly studies the preparation technology of tantalum powder for high CV tantalum capacitor by potassium fluotantalate reduction with sodium. By studying the reaction mechanism of potassium fluotantalate reduction with sodium, it discovers the concentration of potassium fluotantalate and the reduction temperature are two important factors influencing the performance of tantalum powder. From contrast test we can know:When the concentration of potassium fluotantalate reduces, the Fisherparticlesize of tantalum powder will diminish and the content of oxygen and potassium will increase. As the reduction temperature goes up, the Fisherparticlesize of tantalum powder will amplify and the content of oxygen and potassium will decrease. After analyzing the data and combining the particle size with the CV of tantalum powder, the thesis determines the optimal parameters of potassium fluotantalate reduction with sodium for various specifications high CV tantalum powder.Taking16V-70000μF·V/g tantalum powder experiment for example, the thesis discusses the parameters of the heat treatment and reduction by magnesium,which affects the properties of tantalum powder. It is appropriate that the temperature of heat treatment should be between1100℃to1300℃。 When it is too low, tantalum powder will not be agglomerate,the particle strength will be low and the fine powder proportion will be large, which will cause bad liquidity; When the temperature is too high,the sintering performace of tantalum powder will become more obvious, apparent density will increase, particle size will amplify and the percentage of fine powder reduce,which will make the flow performance better. As for the electric properties of tantalum powder, low temperature makes the leakage current rise. While high temperature makes the leakage current decrease, and the BET and the CV decline. In the oxygen reduced treatment, the dosage of magnesium should be excessive.It is appropriate that it is three times the weight of oxygen.The result of deoxidization is not evident when the temperature of reaction is below900℃.The higher the temperature is,the better the result of deoxidization will be.However,if the temperature is too high, the BET and the CV of tantalum powder will descend.The time of reaction must be at least3h.Otherwise,it can’t ensure the effect of deoxidization.