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Anode for use in electrolytic capacitors

A technology of electrolytic capacitors and anodes, applied in the direction of electrolytic capacitors, electrolytic capacitor manufacturing, capacitor electrodes, etc., can solve problems such as difficult and high volumetric efficiency

Inactive Publication Date: 2008-09-24
AVX CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Despite its high surface area, anode frits can exhibit high ESR and capacitance sensitivity to frequency
Further, the frits are generally larger in size than the anode foil, thus making their introduction difficult in applications requiring high volumetric efficiencies

Method used

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  • Anode for use in electrolytic capacitors
  • Anode for use in electrolytic capacitors
  • Anode for use in electrolytic capacitors

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0076] The ceramic body is initially formed from the following composition:

[0077] material Wt%

[0078] Deionized water 19.05

[0079] Nonionic surfactant 0.19

[0080] Anionic polymer dispersant 1.30

[0081] Acrylic adhesive 9.76

[0082] Nb 2 O 5 Powder 69.70

[0083] The ingredients were ground in a dedicated M-18 vibratory mill. Once formed, the composition is degassed in a slip pot by stirring for 24 hours. The slip was cast into 0.001875 inch (1.875 mil) tapes on a polypropylene support. The carrier with the wetting strip floats across a water bath maintained at a constant temperature of 50°C for 2 minutes to promote drying. At the end of the drying phase, the metal knife edge separates the cast strip from the carrier and the strip is rolled along with the single sheet of paper to prevent the strip from sticking to itself during storage. Cut 6” x 6” pieces from the strip. Then 9 of these pieces of the strip were stacked on top of each other and glued together under a...

Embodiment 2

[0085]A wet electrolytic capacitor was formed from the ceramic body of Example 1. Initially, a stainless steel screen (150×150 mesh, obtained from McMaster) was cut into a rectangle of 2.2 cm×1.1 cm. The cathode lead (annealed stainless steel 304 wire of 150 microns in gauge) was cut into a length of 2.5 cm. These rectangles and lines were then first rinsed in an ultrasonic bath in soapy water at 45°C for 30 minutes and then rinsed with deionized ("DI") water 4 times. After drying in an oven at 85°C for 30 minutes, the sample was again degreased in acetone at ambient temperature for 20 minutes. The sample was dried in an oven at 85°C to remove all remaining acetone, rinsed with deionized water 5 times and then dried in an oven at 85°C. A spot welder was used to weld the cathode lead to the center of the 1.1 cm edge of the rectangular screen. The depth is about 1.0mm. Then at 1.0 vol% H 2 SO 4 The rectangular mesh was etched in a solution of 0.1 vol% HCl for 1 minute, degreasing wi...

Embodiment 3

[0104] The capacitor was formed as described in Example 2 with the difference that carbon black was not used in the cathode ink. The resulting cathode loading was 0.0107 g. The capacitance measured at 0.1 Hz is 2.57mF, 2.42mF and 2.37mF for 2.0V, 5.0V and 8.0V bias voltages, respectively. The ESR at a frequency of 1000 Hz is 1.98Ω. The cathode capacitance is estimated to be 550.0mF.

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Abstract

A capacitor anode that is formed from ceramic particles (e.g., Nb2O5, Ta2O5) capable of being chemically reduced to form an electrically conductive composition (e.g., NbO, Ta) is provided. For instance, a slip composition containing the ceramic particles may be initially formed and deposited onto a carrier substrate in the form of a thin layer. If desired, multiple layers may be formed to achieve the target thickness for the anode. Once formed, the layer(s) are subjected to a heat treatment to chemically reduce the ceramic particles and form the electrically conductive anode. Contrary to conventional press-formed anodes, the slip-formed anodes of the present invention may exhibit a small thickness, high aspect ratio (i.e., ratio of width to thickness), and uniform density, which may in turn may lead to an improved volumetric efficiency and equivalent series resistance ('ESR').

Description

Technical field [0001] The present invention relates to electrolytic capacitors, in particular to the anode of electrolytic capacitors. Background of the invention [0002] Electrolytic capacitors are increasingly used in circuit design due to their volumetric efficiency, reliability and process compatibility. Generally, electrolytic capacitors have a larger capacitance / unit volume than some other types of capacitors, which makes electrolytic capacitors useful in relatively high current and low frequency circuits. One type of capacitor that has been developed is a wet electrolytic capacitor, which includes an anode, a cathode, and a liquid or "wet" working electrolyte. Wet electrolytic capacitors often provide a good combination of high capacitance and low leakage current. In some cases, wet electrolytic capacitors can exhibit advantages over solid electrolytic capacitors. For example, wet electrolytic capacitors can operate at a higher operating voltage than solid electrolytic c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01G9/04H01G9/042H01G13/00H01G9/00H01G9/008H01G9/048
CPCY10T29/49204H01G9/0032Y10T29/417H01G9/052H01G9/04H01G9/048
Inventor B·琼斯C·L·恩格丁A·布特勒宁刚K·普尔C·W·尼斯
Owner AVX CORP