Tantalum Capacitor Failure Analysis

A tantalum capacitor is a type of electrolytic capacitor. It is constructed of a pellet of tantalum metal as anode, covered by an insulating oxide layer that forms the dielectric (manganese dioxide), surrounded by conductive material as a cathode (carbon with a silver epoxy interface). Tantalum electrolytic capacitors exploit the tendency of tantalum to form a non-conductive protective oxide surface layer. A tantalum capacitor consists of tantalum powder pressed into a pellet shape as one “plate” of the capacitor, with the oxide as a dielectric, and an electrolytic solution or conductive solid as the other “plate”. The dielectric layer thus can be very thin. This gives tantalum capacitors an advantage over electrolytic capacitors in having a high capacitance per unit volume and weight.