Showing papers on "Tantalum capacitor published in 2021"

Evolution of Polymer Tantalum Capacitors

Abstract: The major advantage of Polymer Tantalum capacitors over other types of tantalum capacitors is their low equivalent series resistance (ESR), providing a higher capacitance stability with frequency and ripple current capability. When Polymer Tantalum capacitors were introduced to the market in mid 1990s, they were low voltage, leaky, and unreliable, which limited their applications to commercial electronics. Today, some types of polymer tantalum capacitors demonstrate the highest working voltage, lowest DC leakage, and highest reliability ever achieved in tantalum capacitors. These Polymer Tantalum capacitors combine outstanding performance and reliability with superior volumetric charge efficiency, which makes them cost effective and attractive for numerous applications, including mission critical ones. This paper is dedicated to the major technological breakthroughs and scientific discoveries that enabled the radical evolution of Polymer Tantalum capacitors.

Popcorning Failures in Polymer and MnO2 Tantalum Capacitors

Abstract: Popcorning is a well-known effect in plastic encapsulated microcircuits (PEM) and it occurs in chip tantalum capacitors. The sensitivity of components to the presence of moisture during soldering is characterized by the moisture sensitivity level (MSL); however, contrary to PEMs, there is no standard procedure for establishing MSL for tantalum capacitors. The effect of absorbed moisture on soldering related degradation and failures in tantalum capacitors have not been studied properly yet, and there is no sufficient information regarding the difference in the sensitivity to soldering between polymer and MnO2 capacitors. In this work, 16 types of polymer and 9 types of MnO2 tantalum capacitors with different moisture content have been tested before and after reflow soldering. The level of moisture release during soldering has been estimated and thermo-mechanical analysis used to assess deformation of capacitors during soldering simulations. Results show that moisture uptake in similar parts is approximately two times greater in polymer than in MnO2 capacitors. Cracking of the case and degradation of parameters can occur in both types of parts, but MnO2 capacitors are much more likely to fail catastrophically with a short circuit and possible ignition during the first power-on cycle. This type of failure in MnO2 capacitors is lot-related, can occur even at derated voltages and relatively low levels of moisture sorption that corresponds to room conditions. Baking before soldering is an effective measure to prevent failures even in lots susceptible to popcorning damage.

Breakdown and Self-healing in Tantalum Capacitors

Abstract: In this work, different types of polymer and MnO 2 cathode capacitors are tested for scintillation breakdown using a constant current stress (CCS) technique modified to allow detection of amplitudes and duration of current spikes. Monitoring of leakage currents with time under bias is used to assess the effect of scintillations. The appearance and composition of damaged sites are examined after deprocessing and cross-sectioning. Thermal processes during scintillations are analyzed, a mechanism of breakdown based on growth of conductive filaments in the dielectric is suggested, and self-healing processes in polymer and MnO 2 cathode capacitors is discussed.

Tantalum Capacitor With Increased Stability

Abstract: A solid electrolytic capacitor containing a capacitor element is provided. The capacitor element contains an anode body that contains tantalum, a dielectric that overlies the anode body; and a solid electrolyte that overlies the dielectric. The solid electrolyte includes an intrinsically conductive polymer containing repeating thiophene units. Further, the capacitor exhibits a dielectric strength of about 0.6 volts per nanometer or more. The capacitor also exhibits a charge-discharge capacitance after being subjected to 3,000 cycles of a surge voltage and an initial capacitance prior to being subjected to the surge voltage, wherein the ratio of the charge-discharge capacitance to the initial capacitance is from about 0.75 to 1.

Effect of High Temperature Storage on AC Characteristics of Polymer Tantalum Capacitors

Abstract: Replacement of MnO2 with conductive polymers as cathode materials in chip tantalum capacitors allows for a substantial reduction of the equivalent series resistance (ESR), improvement of frequency characteristics, and elimination of the possibility of ignition during failures. One of the drawbacks of chip polymer tantalum capacitors (CPTCs) is a relatively poor long-term stability at high temperatures. In this work, variations of capacitance, dissipation factor, and ESR in different types of capacitors including automotive grade parts from three manufacturers have been monitored during storage at temperatures from 100 °C to 175 °C for up to 18,000 hours. Results show that ESR is the most and capacitance the least sensitive to degradation parameter. Times to parametric failures have been simulated using a Weibull-Arrhenius model that allowed for assessments of activation energies of the degradation and prediction of times to failure at the use temperature. Degradation of CPTCs was explained by thermo-oxidative processes in conductive polymers that result in exponential increasing of the resistivity with time of ageing. This process starts after a certain incubation period that depends on packaging materials and design and corresponds to the time that is necessary to form delamination between the encapsulating molding compound and lead frame. The effectiveness of the existing qualification procedures to assure stable operation of CPTCs is discussed.

Method of manufacturing anodes of tantalum capacitor

Abstract: FIELD: electricity.SUBSTANCE: invention relates to production of electric capacitors. Method of producing tantalum capacitor anodes involves mixing anhydrous tantalum powder and binder, pressing anodes of condensers into workpieces, subliming the binder, treating the workpieces with a solution of a surfactant, washing the workpieces with desalted water, vacuum drying and vacuum sintering of tantalum anodes. Binder used is camphor or stearic acid solution in ethyl alcohol. Surfactant used is an aqueous solution of sulphanol and / or synthanol. After molding and sublimation, anode workpieces are treated with surfactant solution, followed by washing with desalted water at high temperature and stirring. Drying of blanks is carried out in vacuum at temperature 150-160°C, residual pressure of not more than 0.15 Pa and duration of not less than 20 minutes.EFFECT: obtaining anodes without defects with reduction of residual content of carbon.1 cl, 1 tbl, 4 ex