Tantalum capacitor

About: Tantalum capacitor is a research topic. Over the lifetime, 2432 publications have been published within this topic receiving 26709 citations.

Dielectric Breakdown in Electrolytic Capacitors

Abstract: Starting with the known but unexplained fact that high‐voltage electrolytic capacitors need operating electrolytes of high resistivity, breakdown (sparking) voltages of aluminum and tantalum anodes have been examined. If interfering side reactions are eliminated, breakdown voltage increases linearly with the logarithm of electrolyte resistivity and is insensitive to variations in electrolyte composition and to changes in temperature between 65°C and 95°C.

Electrolytes for capacitors

Abstract: The present invention is directed to an electrolyte for an electrolytic capacitor. The capacitor has an electrolytic anode and an electrochemical cathode. The electrolyte has water, a water soluble organic salt, and a relatively weak organic acid. This electrolyte is chemically compatible to aluminum and tantalum oxide dielectrics and withstands higher voltage while maintaining good conductivity. This makes the electrolyte especially useful for high voltage applications, such as occur in an implantable cardiac defibrillator.

Method for manfacturing a capacitor for a semiconductor memory device having a tautalum oxide film

Abstract: A capacitor for a semiconductor memory device employs a tantalum pentoxide film as a dielectric film. The dielectric film is made from tantalum pentoxide film doped with silicon over a first electrode. A second electrode is then formed over the dielectric film. Accordingly, in the method for manufacturing the device, although the dielectric constant of the dielectric film is somewhat lower than the conventional pure tantalum pentoxide film due to the silicon doped within the tantalum pentoxide film, leakage current is reduced and breakdown voltage is increased. Therefore, the dielectric film according to the present invention exhibits excellent electrical characteristics and high reliability.

Isolated AC/DC Offline High Power Factor Single-Switch LED Drivers Without Electrolytic Capacitors

Abstract: Energy-efficient residential lighting such as household light-emitting diode (LED) lamps with ac input require an ac/dc converter (or driver) with large output capacitance to minimize the low frequency LED current ripple. The energy storage capacitor used in the conventional ac/dc LED driver is usually an electrolytic capacitor due to its low cost and high energy density. However, the average lifetime of an electrolytic capacitor is at least 2–3 times less than that of an LED device. Hence, the potential lifetime of the LED lamp is significantly affected by the presence of the electrolytic capacitor in the driver circuit. In this paper, two novel isolated single-switch ac/dc high power factor LED drivers without using any electrolytic capacitors are proposed. In the proposed circuits, the energy storage capacitor is moved to the rectifier side, with a three-winding transformer used to provide isolation; input power factor correction as well as to store and provide the required energy to the output. As a result, the energy storage capacitance is significantly reduced, which allows film capacitor to be used to replace the conventionally used electrolytic capacitors. The circuit’s operating principles and its characteristics are described in this paper. Simulation and experimental results are given on a 120 $\text{V}_{\rm rms}$ , 12 W prototype to confirm that a power factor of at least 0.96 is achieved.

Method of making trench-incorporated monolithic semiconductor capacitor and high density dynamic memory cells including the capacitor

Abstract: A high density integrated circuit structure, for example a dynamic memory cell, is described which includes an active/passive device in combination with a capacitor structure. The capacitor structure is of the polysilicon-oxide-silicon type and is formed on the sidewalls of a mesa-shaped and dielectrically isolated region of silicon material resulting from the formation of an isolation trench in the silicon. The trench is filled with a plastic material, such as polyimide. The capacitor is formed by the isolated region of silicon material which functions as the first capacitor plate, a doped polysilicon layer provided on the vertical walls of the mesa serving as the second capacitor plate and a thin dielectric layer interposed between the two plates serving as the capacitor's dielectric. Since the polysilicon is wrapped around the periphery of the mesa as a coating on the vertical sidewalls thereof, it gives rise to a large storage capacitance without an increase in the cell size.