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. This results in a higher capacitance value per volume, superior frequency characteristics compared to many other types of capacitors and excellent stability over time. Tantalum capacitors are generally polarized, which means that they may only be connected to a DC supply observing the correct terminal polarity. The downside to using tantalum capacitors is their unfavorable failure mode which may lead to thermal runaway, fires and, small explosions, but this can be prevented through the use of external failsafe devices such as current limiters or thermal fuses. These surface mount tantalum capacitors claim much less space on the printed circuit board and allow for greater packing densities.

These tantalum capacitors had higher than normal leakage current.  The capacitor failed in four different areas. Typically, tantalum capacitors are derated to ensure the operating voltage will never exceed the voltage of the capacitor. If it does, a short will result causing a breakdown in the manganese dioxide. Other sources of leakage current are contamination within the encapsulation. Tantalum capacitors are very stable throughout their lives and do not degrade like electrolytic capacitors.

Constant vigilance is required to monitor your process, your design, your components, your manufacturing facility, your application, and your installation environment. Gideon Analytical Labs has the experience to help you out with any of these areas and get to the root of the cause. 845-255-5356.