Tantalum in Solid Electrolytic Capacitors—New Developments

Tantalum capacitors play an important part in modem electronics. They are used in the most demanding of circuit applications, because of their outstanding characteristics, such as: compatibility with Surface Mounted Technology, small size, ability to operate over relatively wide temperature spectrum, and high reliability. Whereas the production of capacitors more than tripled over the last eight years, the amount of powders needed for this increase grew by no more than 10%. One of the main reasons for this development has been the achievement of powder producers to increase the capacitance/g of Tantalum powder. Today there are powders available with a CV/g value of 40-50 K and higher. The development of high CV powders was a complicated process made possible by using finer powders, the introduction of sophisticated agglomeration techniques and deoxidization. High capacitance powders have to be sintered at lower temperatures or shorter sinter times to preserve the high surface area. The lowering of sintering temperature results in decreasing the purification of the powder during sintering. Therefore, high capacitance powders have to be purer before the sintering than low capacitance powders of the past.