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.

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Failure Analysis on T491D475K050AT Kemet Tantalum Capacitor

Failure Analysis on T491D475K050AT Kemet Tantalum Capacitor

Gideon Analytical Laboratories received several T491D475K050AT Kemet tantalum capacitors for electronic failure analysis. A capacitor is a passive two-terminal electronic component that stores electrical energy in an electric field. While some capacitance exists between any two electrical conductors in proximity in a circuit, a capacitor is a component designed to add capacitance to a circuit. The Kemet T491D475K050AT has a capacitance of 4.7 uF, a voltage rating of 50 VDC, and a tolerance of 10%, measures 7.
Vishay TR3D685K050C0500 Tantalum Capacitors

Vishay TR3D685K050C0500 Tantalum Capacitors

Gideon Analytical Laboratories received several Vishay TR3D685K050C0500 tantalum capacitors for analysis. A tantalum electrolytic capacitor is an electrolytic capacitor, a passive component of electronic circuits. It consists of a pellet of tantalum metal as an anode, covered by an insulating oxide layer that forms the dielectric, surrounded by a liquid or solid electrolyte as a cathode. Because of its very thin and relatively high permittivity dielectric layer, the tantalum capacitor distinguishes itself from other conventional and electrolytic capacitors in having a high capacitance per volume (high volumetric efficiency) and lower weight.
Surface Mount Tantalum Capacitors 2

Surface Mount Tantalum Capacitors 2

Gideon Analytical Laboratories received two surface mount (SM) tantalum capacitors that had internal resistive shorts. Capacitors are passive, two-terminal electrical components used to store energy. They vary in construction, but all have at least two electrical conductors that are separated by an insulator, known as a dielectric. Tantalum capacitors are a type of electrolytic capacitor, which are ubiquitous in electronic circuits. Tantalum capacitors have a high capacitance per volume and weight and are more expensive than any other commonly used capacitor.
Tantalum Capacitor Failure Analysis

Tantalum Capacitor Failure Analysis

Gideon Analytical Labs received four tantalum capacitors identified as failing from two vendors, Kemet (T491B225K035AT) and AVX TAJB225K035RNJ. 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.
Counterfeit 476E Tantalum Capacitors

Counterfeit 476E Tantalum Capacitors

Gideon Analytical Labs receives many counterfeit parts come in from Asia and China. Constant testing and evaluation with radiography, cross-sectioning, and electrical measurements and microscopy provide the means to identify these components flooding our markets. Tantalums capacitors are made of tantalum metal which acts as an anode, covered by a layer of oxide which acts as the dielectric, surrounded by a conductive cathode. The use of tantalum allows for a very thin dielectric layer.
Kemet T491C155M035AT Surface Mount Tantalum Capacitors

Kemet T491C155M035AT Surface Mount Tantalum Capacitors

Gideon Analytical Laboratories received two surface mount T491C155M035AT Kemet tantalum capacitors with internal resistive shorts. These capacitors have standard capacitance tolerances of ±10% and ±20%, with an operational temperature -55°C to +85°C rated voltage and up to +125°C with voltage derating in applications utilizing recommended series resistance. They have low leakage and are ROHS compliant. The goal was to determine the reason for the failure. There was no damage tothe external plastic encapsulation of the package to indicate mechanical stress, which would weaken the package integrity.