Showing papers on "Tantalum capacitor published in 2010"

Process for producing electrolytic capacitors with a polymeric outer layer

Abstract: The invention relates to a process for producing electrolytic capacitors with low equivalent series resistance, low residual current and high thermal stability, which consist of a solid electrolyte and an outer layer comprising conjugated polymers, to electrolytic capacitors produced by this process and to the use of such electrolytic capacitors.

High voltage and high efficiency polymer electrolytic capacitors

Abstract: A capacitor, and method of making a capacitor, is provided wherein the capacitor has exceptionally high break down voltage. The capacitor has a tantalum anode with an anode wire attached there to. A dielectric film is on the tantalum anode. A conductive polymer is on the dielectric film. An anode lead is in electrical contact with the anode wire. A cathode lead is in electrical contact with the conductive polymer and the capacitor has a break down voltage of at least 60 V.

Solid electrolytic capacitor for use in high voltage and high temperature applications

Abstract: A capacitor assembly for use in high voltage and high temperature environments is provided. More particularly, the capacitor assembly includes a solid electrolytic capacitor element containing an anode body, a dielectric overlying the anode, and a solid electrolyte overlying the dielectric. To help facilitate the use of the capacitor assembly in high voltage applications, it is generally desired that the solid electrolyte is formed from a dispersion of preformed conductive polymer particles. In this manner, the electrolyte may remain generally free of high energy radicals (e.g., Fe 2+ or Fe 3+ ions) that can lead to dielectric degradation, particularly at relatively high voltages (e.g., above about 60 volts). Furthermore, to help protect the stability of the solid electrolyte at high temperatures, the capacitor element is enclosed and hermetically sealed within a housing in the presence of a gaseous atmosphere that contains an inert gas. It is believed that the housing and inert gas atmosphere are capable of limiting the amount of oxygen and moisture supplied to the conductive polymer of the capacitor. In this manner, the solid electrolyte is less likely to undergo a reaction in high temperature environments, thus increasing the thermal stability of the capacitor assembly. In addition to functioning well in both high voltage and high temperature environments, the capacitor assembly of the present invention may also exhibit a high volumetric efficiency.

Solid electrolytic capacitors with improved reliability

Abstract: A capacitor with an anode, a dielectric on the anode and a cathode on the dielectric. A blocking layer is on the cathode. A metal filled layer is on said blocking layer and a plated layer is on the metal filled layer.

High capacitance trench capacitor

Abstract: A dual node dielectric trench capacitor includes a stack of layers formed in a trench. The stack of layers include, from bottom to top, a first conductive layer, a first node dielectric layer, a second conductive layer, a second node dielectric layer, and a third conductive layer. The dual node dielectric trench capacitor includes two back-to-back capacitors, which include a first capacitor and a second capacitor. The first capacitor includes the first conductive layer, the first node dielectric layer, the second conductive layer, and the second capacitor includes the second conductive layer, the second node dielectric layer, and the third conductive layer. The dual node dielectric trench capacitor can provide about twice the capacitance of a trench capacitor employing a single node dielectric layer having a comparable composition and thickness as the first and second node dielectric layers.

Performance and Reliability Study of High Voltage Tantalum Polymer Capacitors

Abstract: The need for reliable components with smaller form factors continues to drive many of the innovation efforts within the passive components community. For applications requiring the smallest component options available, tantalum chip capacitors remain the best option for capacitance values that exceed the reaches of MLCC capacitors. Today, the best options for higher capacitance needs are being met by both MnO2 and polymer tantalum chip capacitors as well as surface mount aluminum electrolytic capacitors. As with all component technologies, each has its own set of strengths and weaknesses that designers must take into account when making their component selections. Among these are the capacitance range, voltage range, impedance characteristics, reliability, and physical size.

Solid Electrolytic Capacitor Assembly

Abstract: A capacitor assembly that includes a solid electrolytic capacitor element containing an anode body, a dielectric overlying the anode, and a solid electrolyte (e.g., conductive polymer) overlying the dielectric is provided. The anode body is in electrical contact with an anode termination and the solid electrolyte is in electrical contact with a cathode termination. The capacitor element and terminations are encapsulated within a resinous material so that at least a portion of the terminations remain exposed. In addition to enhancing mechanical robustness, the resinous encapsulating material acts in some capacity as a barrier to moisture and oxygen during use, which could otherwise reduce the conductivity of the solid electrolyte and increase ESR. To even further protect the capacitor element, especially at high temperatures, the encapsulated capacitor element is also enclosed and hermetically sealed within a ceramic housing in the presence of an inert gas. It is believed that the ceramic housing is capable of limiting the amount of oxygen and moisture supplied to the conductive polymer of the capacitor. In this manner, the solid electrolyte is less likely to undergo a reaction in high temperature environments, thus increasing the thermal stability of the capacitor assembly.

Solid electrolytic capacitor and fabrication method thereof

Abstract: A solid electrolytic capacitor comprising an anode composed of a valve metal or its alloy, a dielectric layer formed on a surface of the anode, a coupling agent layer formed by subjecting the dielectric layer to a surface treatment with a coupling agent having a phosphonic acid group, a conductive polymer layer formed on the coupling agent layer, and a cathode layer formed on the conductive polymer layer.

Energy storage in edlcs by utilizing a dielectric layer

Abstract: A composition comprising an electrode or an electrical double-layer capacitor with dielectric material is disclosed, along with methods of making the composition. The present invention improves upon state-of-the-art electrodes and capacitors by coating a material of high dielectric constant onto the surface of the electrode to produce improved electrical properties. The composition is particularly useful for design of novel electrical double-layer capacitors.

Solid electrolytic capacitor element and manufacturing method therefor

Abstract: A solid electrolytic capacitor containing a solid electrolytic capacitor element with increased heat resistance, resistance to leakage current, and a low ESR and high reliability, includes a solid electrolytic capacitor element having a dielectric layer, a solid electrolyte layer, a carbon paste layer, and a conductive paste layer sequentially stacked on a surface of a valve acting metal plate, where the carbon paste layer has an end thereof on the solid electrolyte layer, the end of the carbon paste layer is covered with an insulating resin layer, and the largest thickness of the capacitor element in the section of the insulating resin layer is not more than the largest thickness of the capacitor element in the section of the conductive paste layer. A manufacturing method is also described.

Method for measuring capacitances of capacitors

Abstract: A capacitor measurement circuit for measuring a capacitance of a test capacitor includes a first transistor with a first source-drain path coupled between a first capacitor plate of the test capacitor and a ground; a second transistor with a second source-drain path coupled between a second capacitor plate of the test capacitor and the ground; and a current-measuring device configured to measure a first charging current and a second charging current of the test capacitors. The first and the second charging currents flow to the test capacitor in opposite directions.

Solid electrolytic capacitor and method of manufacturing thereof

Abstract: A solid electrolytic capacitor having a high heat resistance is provided. The solid electrolytic capacitor according to the present invention includes an anode body having a surface on which a dielectric film is formed, and a conductive polymer layer formed on the dielectric film. The conductive polymer layer includes an aromatic sulfonic acid ion and an NHPA compound ion.

Degradation of leakage currents in solid tantalum capacitors under steady-state bias conditions

Abstract: Degradation of leakage currents in various types of solid tantalum capacitors under steady-state bias conditions was investigated at temperatures from 105 °C to 170 °C and voltages up to two times the rated voltage. Variations of leakage currents with time under highly accelerated life testing (HALT) and annealing, thermally stimulated depolarization currents, and I-V characteristics were measured to understand the conduction mechanism and the reason for current degradation. During HALT the currents increase gradually up to three orders of magnitude in some cases, and then stabilize with time. This degradation is reversible and annealing can restore the initial levels of leakage currents. The results are attributed to migration of positively charged oxygen vacancies in tantalum pentoxide films that diminish the Schottky barrier at the MnO2/Ta2O5 interface and increase electron injection. A simple model allows for estimation of concentration and mobility of oxygen vacancies based on the level of current degradation.

Temperature-independent capacitor and capacitor module

Abstract: The invention relates to a capacitor comprising the following components: a first heating element (1), a first capacitor region, comprising: dielectric layers (3), internal electrodes (4) which are arranged between the dielectric layers, wherein the first heating element and the first capacitor region (2) are connected to each other in a thermally conductive manner.

Capacitor with three-dimensional high surface area electrode and methods of manufacture

Abstract: A capacitor, and methods of its manufacture, having improved capacitance efficiency which results from increasing the effective area of an electrode surface are disclosed. An improved "three-dimensional" capacitor may be constructed with electrode layers having three-dimensional aspects at the point of interface with a dielectric such that portions of the electrode extend into the dielectric layer. Advantageously, embodiments of a three- dimensional capacitor drastically reduce the space footprint that is required in a circuit to accommodate the capacitor, when compared to current capacitor designs. Increased capacitance density may be realized without using high k (high constant) dielectric materials, additional "electrode - dielectric - electrode" arrangements in an ever increasing stack, or serially stringing together multiple capacitors.

Solid electrolytic capacitor and method for producing same

Abstract: A solid electrolytic capacitor that is able to maintain a high capacitance and low ESR, and also exhibits a high degree of heat resistance. The solid electrolytic capacitor 10 is produced by winding a porous anode foil 11 having a dielectric layer formed thereon, and a cathode foil 13 b, with a separator having a solid electrolyte 13 a supported thereon disposed therebetween, wherein the solid electrolyte 13 a comprises at least a conductive complex having a cationized conductive polymer and a polymer anion, and not more than 7% by mass of water.

Investigating pre-breakdown currents in polymer tantalum capacitors

Abstract: Poly(3,4-ethylenedioxythiophene) (PEDOT), a conducting polymer, has been used since the 1990s for the cathode of tantalum capacitors, which have a tantalum anode, and a layer of tantalum pentoxide as the dielectric. Such capacitors are referred to as Polymer Ta capacitors. The first method, an in situ polymerization technique, used to deposit the polymer resulted in capacitors with a significant leakage current and breakdown voltages near 50 V. The second method, a pre-polymerization (pre-poly) technique, resulted in capacitors that have a much lower leakage current and a higher breakdown voltage than the in situ capacitors. In this thesis, an accurate measurement technique for dielectric leakage current, also referred to as the pre-breakdown current, was established for capacitors. Current versus time measurements at constant voltage were performed at several voltages and the results were compiled to obtain the current-voltage (I-V) characteristics of both in situ and pre-poly types of capacitors. These characteristics were then modeled and analyzed, which led to the conclusion that the pre-breakdown current is controlled by the Poole-Frenkel mechanism in the in situ capacitors and by both the Poole-Frenkel and Schottky mechanisms in the pre-poly capacitors. Current versus time measurements were also performed at various temperatures to obtain the activation energy for the current in the capacitors and to verify the leakage mechanisms. Results suggest the presence of shallow 0.15 eV traps in the dielectric of the in situ capacitor and deeper 0.75 eV traps in that of the pre-poly capacitor. Additionally, pre-poly capacitors also have a 0.54 eV Schottky barrier that limits the electrons from being emitted into the dielectric from the electrode. Both the deep trap levels and the Schottky barrier explain the lower leakage current and higher breakdown voltage observed in the pre-poly capacitors as compared to the in situ capacitors.

Semiconductor Device Comprising a Buried Capacitor Formed in the Contact Level

Abstract: In a semiconductor device, capacitors may be formed so as to be in direct contact with a transistor by using a shared transistor region, such as a drain region or a source region of closely spaced transistors, as one capacitor electrode, while the other capacitor electrode is provided in the form of a buried electrode in the dielectric material of the contact level. To this end, dielectric material may be deposited so as to reliably form a void, wherein, at any appropriate manufacturing stage, a capacitor dielectric material may be provided so as to separate the capacitor electrodes.

Integrated nano-farad capacitors and method of formation

Abstract: A high value capacitance per unit area capacitor is fabricated on a substrate 1 by converting a portion of a primary function anti-reflecting conducting layer 36 to a high value dielectric layer 37 by partially oxidizing the conducting layer to form the dielectric layer. The resultant combination is sandwiched between two metal layer electrodes 35 and 55 to complete the capacitor structure.

The study on the thickness change of tantalum oxide as voltage drop in electrolyte

Abstract: — Tantalum oxide (Ta 2 O 5 ) films are of considerable interest for a range of application, including optical waveguide devices, high temperature resistors, and oxygen sensors. In this paper, we establish an anode oxidation process of tantalum thin film. The voltage drop in the electrolyte is affected not in voltage change but in current change. If the voltage drop in the electrolyte is same with cathode oxidation voltage, the current changes logarithmically in proportion to the voltage drop in interface of tantalum oxide and electrolyte. As a result of the measurement on the electrical property of tantalum oxide thin film, when the thickness of the insulator film is 1500 Å , the breakdown voltage is 350volts and dielectric constant is 29. Index Terms — tantalum oxide thin film, Anode oxidation, Electrolyte, Breakdown voltage, Dielectric constant etc. I. INTRODUCTION The tantalum oxide thin film is most extensively used with dielectric material in devices. Because of their high dielectric constant, in recent years they have received increasing attention as a possible alternative dielectric to replace thin SiO

Impact of top electrode on electrical stress reliability of metal-insulator-metal capacitor with amorphous ZrTiO4 film

Abstract: For metal-insulator-metal (MIM) capacitors with an amorphous ZrTiO4 film as the dielectric, the impact of top electrode including Ni and Al on electrical stress reliability was studied and the mechanisms to explain the electrode-dependent reliability were also proposed in this work. It has been found that the Ni-electrode MIM capacitors reveal good reliability in terms of 0.91% capacitance change after ten-year operation under −2 V constant voltage stress while that for those with Al electrode degrades to 1.92%. This undesirable higher capacitance change can be mainly ascribed to a larger permittivity modulation in the dielectric that is due to higher leakage current and consequently more trapped charges and dipoles caused by a lower electrode work function. In addition, a parasitic Al2O3 film in the Al-electrode MIM capacitors also worsens the integrity of the dielectric because of the existence of additional traps.

Apparatus and method for screening electrolytic capacitors

Abstract: A method for screening electrolytic capacitors places a capacitor in series with a resistor, applying a test voltage and following the charge curve for the capacitor. A high voltage drop across the capacitor indicates high reliability and a low voltage drop is used to reject the piece. The leakage current is not adversely affected during the test.

Low Voltage Specific Charge (CV/g) Loss in Tantalum Capacitors

Abstract: The systematic decrease in charge per unit weight (CV/g) in electrolytic tantalum capacitors as a function of decreasing anodization voltage is explored from both experimental and theoretical viewpoints for a range of tantalum particle sizes. Analysis by transmission electron microscopy shows that a native thermal oxide about 3.3 nm in thickness is present on the tantalum surface before anodization and that the thickness is independent of tantalum particle size. Studies in which the initial oxide thickness is altered via a preanodization heat-treatment show that the anodic oxide thickness becomes independent of the initial thermal oxide thickness once its thickness is exceeded. A theoretical model based on a cylindrical geometry explains the loss in the CV/g with decreasing anodization voltage and attributes the behavior to the 3.3 nm oxide thickness corresponding to zero anodization voltage.

Mechanically robust solid electrolytic capacitor assembly

Abstract: An integrated capacitor assembly that contains at least two solid electrolytic capacitor elements electrically connected to common anode and cathode terminations is provided. The capacitor elements contain an anode, a dielectric coating overlying the anode that is formed by anodic oxidation, and a conductive polymer solid electrolyte overlying the dielectric layer. The capacitor elements are spaced apart from each other a certain distance such that a resinous material can fill the space between the elements. In this manner, the present inventors believe that the resinous material can limit the expansion of the conductive polymer layer to such an extent that it does not substantially delaminate from the capacitor element. In addition to possessing mechanical stability, the capacitor assembly also possesses a combination of good electrical properties, such as low ESR, high capacitance, and a high dielectric breakdown voltage.

Electrode material for aluminum electrolytic capacitor and method for manufacturing the material

Abstract: Disclosed is an electrode material for an aluminum electrolytic capacitor, which has a high porosity and a high capacitance and does not require etching. Specifically, the electrode material for an aluminum electrolytic capacitor is characterized in that the material is composed of a sintered body of aluminum or that of at least one kind of aluminum alloy, and the porosity of the sintered body is 35-55%.