JPS5938043Y2 - Electrode foil for electrolytic capacitors - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the structure of a foil material for electrolytic capacitor electrodes.

In general, electrolytic capacitor electrode foil is made of high-grade or high-purity aluminum foil or high-purity aluminum as a base material, to which small amounts of Ta + Nb p B e p Cu and other alloy components are added. It is manufactured by etching.

In this case, as the degree of etching increases, the surface area expansion rate of the foil, that is, the capacitance of an electrolytic capacitor using this foil increases, but at the same time, the mechanical strength of the electrode foil decreases. arise.

In reality, due to the demand for miniaturization of electronic components, attempts are made to obtain the maximum capacitance by roughening the surface of the foil and expanding its surface area under extreme conditions, and as a result, commercially available electrode foils are able to withstand practical use. The reality is that it has minimal mechanical strength.

However, the demand for smaller electrolytic capacitors has recently become more profitable, and as a result, there is a need to wind up capacitor elements with a smaller winding diameter.
As the automation and speeding up of processes such as width cutting and winding are progressing, the demand for improving the mechanical strength of electrode foils is increasing more than ever.

Therefore, the object of the present invention is to provide a novel electrode foil that has excellent mechanical strength and bending strength, and has a high surface area expansion rate.

Hereinafter, the structure of the electrode foil of the present invention will be explained with reference to the attached drawings.
Explain in detail.

FIG. 1 is an enlarged cross-sectional view showing the layered structure of a laminate material that is the starting material for the electrode foil of the present invention. It is formed by integrally laminating a synthetic resin thin film 2 interposed therebetween.

As the synthetic resin thin film 2, various known synthetic resin films may be appropriately selected and used.

Further, the formation of a laminate is achieved by known means such as bonding with an adhesive or lamination by an extrusion method.

Further, the aluminum purity, type and amount of alloy components added, thickness, temper, etc. of the aluminum foil can be appropriately selected depending on the use of the electrode foil, etc.

Next, this laminated material is subjected to a chemical or electrochemical etching treatment such as an electrolytic etching treatment using a direct current or an alternating current electric field according to a conventional method, and is further subjected to a chemical conversion treatment to obtain the electrode foil of the present invention as shown in FIG.

In FIG. 2, the etched aluminum foils 3, 3 forming both outer layers can contribute to the formation of etched pits with their entire capacity, resulting in an extremely high surface area expansion rate.

On the other hand, the synthetic resin thin film 2 provided in the middle does not suffer from the etching action and functions to maintain the mechanical strength of the entire electrode foil.

For example, in the case of electrolytically etched foil using an alternating current electric field for so-called low voltage applications, relatively shallow pits are formed that do not reach the core, so the interposition of the synthetic resin thin film 2 as a core layer is also necessary for the electrode foil. There is no substantial effect on the capacitance of the capacitor, and the capacitor has a large bending strength that can withstand applications such as small capacitors whose winding radius is extremely small.

Therefore, the electrode foil of the present invention can be said to be suitable for this purpose.

On the other hand, the electrode foil of electrolytic capacitors, which are generally referred to as low-voltage, high-capacity capacitors, is made by electrolytically etching a high-purity aluminum foil with a thickness of 90 to 100 microns in an unrolled hard state using a direct current electric field. Produced by enlarging.

The pits formed when hard foil is electrolytically etched with direct current are fine capillary pits that grow in random directions and are formed over almost the entire thickness of the foil.

Therefore, the mechanical strength of etched foil is extremely weak, and troubles often occur during the rolling process, especially after chemical conversion treatment, even when handled with the utmost care.

Therefore, the electrode foil of the present invention can be said to be suitable for this purpose as well.

In addition, as is well known, high-purity aluminum foil and its alloy foil are extremely expensive materials, and the present invention also achieves a significant reduction in material costs in that it can be reduced by using the minimum necessary amount1. It is something to do.

[Brief explanation of the drawing]

FIG. 1 is an enlarged schematic cross-sectional view showing the laminated structure of the laminated material of the present invention, and FIG. 2 is an enlarged schematic cross-sectional view showing the layer structure of the electrode foil of the present invention. 1... Aluminum foil, 2...-@some resin thin film, 3.
-・Etched aluminum foil.

Claims (1)

[Scope of utility model registration request] An integral laminate of two foils consisting of high-purity aluminum foil and/or high-purity aluminum-based alloy foil and a synthetic resin thin film interposed between them is chemically or electrochemically Electrode foil for electrolytic capacitors made by etching treatment and chemical conversion treatment.