JPS62274615A - Manufacture of winding type solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a method of manufacturing a wound solid electrolytic capacitor.

A conventional solid electrolytic capacitor is constructed by forming an oxide layer, which is a dielectric, on the bottom surface of a valve metal base constituting an anode, and sequentially laminating a semiconductor layer and a conductor layer on the oxide layer.

As the valve metal constituting the anode, metals having a valve action such as aluminum, mental, niobium, and titanium are used, and among these, aluminum and tantalum are often used. The shape of the anode valve metal base is porous sintered body,
Capacitors can be made of plates (foils), wires, etc. Among these, capacitors of the type where plates (foils) are spirally wound can be made into small capacitors with large capacitance.

However, even with this spirally wound type capacitor,
Electrolytic capacitors using conventional electrolytes and JP-A-58-1
A type of capacitor in which two electrode foils are wrapped around a separator paper, such as the capacitor using TCNQ salt described in Publication No. 7609, has a limit in reducing the volume due to its structure.

In addition, when an electrolyte or TCNQ salt is used, the electrical conductivity decreases to 1.
The loss coefficient of the capacitor (
It did not have a positive effect on performance such as tan δ) or impedance characteristics.

Problems to be Solved by the Invention The purpose of the present invention is to solve the conventional problems and to develop a wound-type solid electrolytic capacitor that can be made smaller and smaller in volume than the conventional product, and has improved capacitor performance. The purpose is to provide a manufacturing method.

Means for Solving the Problems The present invention provides a method for manufacturing a solid electrolytic capacitor that can achieve the above objects.

That is, the present invention sequentially forms a semiconductor layer and a conductive layer mainly composed of lead dioxide and lead sulfate on the dielectric oxide layer of the anode valve metal base having the dielectric oxide layer on the optical surface. The present invention relates to a method for manufacturing a wound solid electrolytic capacitor, characterized in that a laminate is produced using a laminate, and then the laminate is spirally wound.

Hereinafter, a method for manufacturing a wound solid electrolytic capacitor according to the present invention will be explained.

As the valve metal substrate used as the anode, any metal having a valve action may be used, such as aluminum, tantalum, niobium, titanium, and alloys using these as substrates. Of these, it is advantageous to use aluminum. The shape of the anode substrate before forming the semiconductor layer and conductor layer is as follows:
Usually, it is plate-shaped (including foil, string, etc.).

The oxide layer on the anode substrate surface page may be an oxide layer of the anode substrate itself provided on the coating layer of the anode substrate, or may be an oxide layer of another dielectric oxide provided on the surface of the anode substrate. It may be. Among these, a layer made of an oxide of the anode valve metal base is preferable. In either case, a conventionally known method can be used to provide the oxide layer. For example, when using aluminum foil as the anode substrate, if the surface of the aluminum foil is electrochemically etched and then electrochemically treated in an aqueous solution of boric acid and ammonium borate, the aluminum foil as the anode substrate can be etched. An oxide layer of alumina dielectric is formed on the wafer. Note that an anode lead wire is connected to the anode valve metal base +C (by caulking, high-frequency bonding, etc.) before and after providing the oxide layer.

The semiconductor layer used in the present invention is composed of a layer containing lead dioxide and lead sulfate as main components.

When the semiconductor layer is composed of a layer whose main components are lead dioxide, which originally plays the role of a semiconductor, and lead sulfate, which is an insulating material, the leakage current value of the capacitor can be reduced depending on the blend of lead sulfate. On the other hand, since the electrical conductivity of the semiconductor layer decreases due to the addition of lead sulfate, for example, the loss factor increases, but the present invention maintains and exhibits a high level of performance compared to conventional solid electrolytic capacitors. It was found out. Therefore, when the semiconductor layer is composed of a mixture of lead dioxide and lead sulfate, the content of lead dioxide in the semiconductor layer is 10% by weight.
Good capacitor performance can be maintained and exhibited over a wide range of compositions, preferably less than 100% by weight, preferably 10 to 95% by weight of lead dioxide and 90 to 5% by weight of lead sulfate. 20-50% by weight of lead dioxide, 80-50% by weight of lead sulfate, and even 2% lead dioxide.
In the range of 75 to 65% by weight of lead sulfate compared to 5 to 35% by weight, the balance between leakage current value and loss coefficient value is very good. If the content of lead dioxide is less than 10% by weight, conductivity deteriorates, resulting in a large loss factor and insufficient capacity. When the lead dioxide content is 100% by weight, the leakage current value becomes large and a large amount of time is required for post-forming or aging after capacitor fabrication, which is disadvantageous in terms of cost.

A semiconductor layer containing lead dioxide and lead sulfate as main components can be formed by chemical precipitation using, for example, an aqueous solution containing lead ions and persulfate ions as a reaction mother liquid.

The concentration of lead ions in the reaction mother liquor is from 0.1 mol/l to a concentration giving saturation solubility, preferably 0.5 mol/l.
to the concentration that gives saturated solubility. If the concentration of lead ions is higher than the concentration that provides saturation solubility, no benefit is observed by adding an increased amount.

Further, when the concentration of lead ions is lower than 0.1 mol/l, there is a problem in that the concentration of lead ions in the reaction mother liquor is too low and the number of applications must be increased. On the other hand, the persulfate ion concentration in the reaction mother liquor is within the range of 0.05 to 0.05 in terms of molar ratio to lead ions. If the concentration of persulfate ions is more than 5% in molar ratio to lead ions, unreacted persulfate ions will remain, resulting in high costs;
If it is less than 05, unreacted lead ions remain and the conductivity deteriorates, which is not preferable.

In the present invention, an oxidizing agent containing no persulfate ions may be added to the reaction mother liquor. The blending amount of the oxidizing agent is determined through preliminary experiments in order to maintain a good balance between the leakage current value and the loss coefficient value of the manufactured capacitor.

Typical examples of compounds that provide lead ion species include lead citrate, lead perchlorate, lead nitrate, lead acetate, basic lead acetate, lead chlorate, lead sulfamate, lead silicon hexafluoride, lead bromate, Examples include lead chloride and lead bromide. Two or more of these compounds that provide lead ion species may be used in combination. On the other hand, typical examples of compounds that provide persulfate ion species include potassium persulfate, sodium persulfate, ammonium persulfate, and the like. Two or more of these compounds that provide persulfate ion species may be used in combination.

Examples of the oxidizing agent include hydrogen peroxide, calcium hypochlorite, calcium chlorite, calcium chlorate, and calcium perchlorate.

The conductor layer provided on the semiconductor layer can be formed by, for example, solidifying a conductive paste, plating, metal vapor deposition, forming a heat-resistant conductive resin film, or the like. As conductive yeast, silver paste, copper coating, aluminum paste,
Carden paste, nickel paste, etc. are preferred, but
These may be used alone or in combination of two or more. When two or more types are used, they may be mixed and layered, or they may be stacked as separate layers. After applying the conductive paste, it is left in the air or heated to solidify.

Examples of plating include nickel plating and copper plating. Further, examples of vapor-deposited metals include aluminum, copper, and the like.

The cathode terminal can be attached to the conductor layer using, for example, a conductive paste, or it can be attached by soldering onto the conductive paste after it has solidified.

In order to spirally form a laminate in which a dielectric oxide layer, a semiconductor layer, and a conductor layer are laminated on the anode valve metal base, it is necessary to use the negative and anode bipolar foils used in electrolytic capacitors using conventional electrolytes. A method is used in which only the above-mentioned laminate is wound using a method of manufacturing a wound element consisting of a laminate, for example, into a spiral shape as shown in FIG. Number of turns,
The winding diameter, winding pitch, etc. can be determined as desired and are not particularly limited.

The wound solid electrolytic capacitor of the present invention constructed as described above can be used as a general-purpose capacitor product for various uses by using an exterior such as a resin mold, a resin case, a metal exterior case, resin dipping, or a laminated film exterior. can do.

Effects of the Invention The wound solid electrolytic capacitor obtained by the method of the present invention can be made smaller and smaller in volume than conventional wound electrolytic capacitors, and has good capacitor performance.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. Table 1 shows the characteristic values of the wound solid electrolytic capacitors on each side.

Implementation P Nori 1 An aluminum foil having a length of 5α and a width of 0.3 ann was used as an anode, and the surface of the foil was electrochemically etched by alternating current. Next, after caulking an anode terminal to the etched aluminum foil, an alumina dielectric layer is formed by electrochemical treatment in an aqueous solution of boric acid and ammonium borate, and a low-voltage etched aluminum chemically formed foil (approximately 20 μF/10 crrL) is formed. I got a prize.

A reaction mother liquor was obtained by mixing a 3.8 mol/l aqueous solution of lead acetate trihydrate and a 4.0 mol/l aqueous solution of ammonium persulfate. The above-mentioned etched aluminum chemical foil was immersed in this reaction mother liquor, excluding the anode terminal, and left at 80° C. for 20 minutes. The semiconductor layer deposited on the dielectric layer was thoroughly washed with water to remove unreacted substances, and then dried under reduced pressure at 100° C. for 1 hour. The resulting semiconductor layer consists of lead dioxide and lead sulfate, and the lead dioxide weighs about 25 times! - It was confirmed by mass spectrometry, X-ray analysis, and infrared spectroscopy that it was contained.

Next, carbon paste was applied to the semiconductor layer and dried. Further, a silver paste was applied thereon and dried at room temperature. Next, the obtained laminate was wound into a spiral shape to produce a capacitor element.Furthermore, the cathode terminal was exposed by soldering on the solidified silver wave strip, and the wound solid electrolytic capacitor was sealed with resin. was created.

Example 2 A wound solid electrolytic capacitor was produced in the same manner as in Example 1, except that the concentration of ammonium persulfate during the formation of the semiconductor layer in Example 1 was changed to 0.4 mol/l. The semiconductor layer at this time is a composition consisting of lead dioxide and lead sulfate,
It was confirmed that about 35% by weight of lead dioxide was contained.

Example 3 A wound solid electrolytic capacitor was produced in the same manner as in Example 1, except that 0.05 mol/l of hydrogen peroxide was further added to the reaction mother liquor used in forming the semiconductor layer in Example 1. . It was confirmed that the semiconductor layer at this time was composed of lead dioxide and lead sulfate, and contained about 50% by weight of lead dioxide.

Example 4 A wound solid electrolytic capacitor was produced in the same manner as in Example 1, except that 0.2 mol/l of hydrogen peroxide was further added to the reaction mother liquor used in forming the semiconductor layer in Example 1. . It was confirmed that the semiconductor layer at this time was composed of lead dioxide and lead sulfate, and contained about 94% by weight of lead dioxide.

Comparative Example 1 Using the same etched aluminum foil as in Example 1, an electrolytic capacitor was fabricated using a stain removal solution by a method known in the art. That is, after winding up an element consisting of an anode foil (etched aluminum foil), a cathode foil, and a separator each with a terminal in a spiral, the wound element is coated with ethylene glycol-ammonium adipate. A wound type electrolytic capacitor was fabricated by impregnating the device with an electrolytic solution, storing the device in an aluminum exterior case, and closing the opening with a rubber sealing body.

Comparative Example 2 Using the same etched aluminum foil as in Example 1, a solid electrolytic capacitor with TCNQ salt as a semiconductor layer was fabricated according to the method described in Japanese Patent Application Laid-open No. 17609/1983. That is, a complex salt of inpropyl inquinoline and TCNQ was placed in an aluminum exterior case and melted by heating. Next, a wound element consisting of an anode foil, a cathode foil, and a separator each having a terminal was preheated and impregnated into the molten TCNQ complex described above, and quickly cooled and solidified. A wound type electrolytic capacitor was produced by closing the opening with a rubber sealing body.

Comparative Example 3 In Example 1, a 0.7 mol/l aqueous solution of lead citrate was used instead of the 3.8 mol/l aqueous solution of lead acetate trihydrate, and the concentration of ammonium persulfate was changed to 4.8 mol/l. A wound solid electrolytic capacitor was produced in the same manner as in Example 1, except that the reaction mother liquor obtained in Example 1 was used.

It was confirmed that the semiconductor layer at this time was composed of lead dioxide and lead sulfate, and contained about 5% by weight of lead dioxide.

Table 1 *Value at 120Hz **Value at 2C1/ *** Relative comparison value with comparative example 1 as 1

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a wound solid electrolytic capacitor according to the present invention. 1... Laminated body, 2... Anode terminal, 3...
・Cathode terminal.

Claims (5)

[Claims] (1) On the dielectric oxide layer of the anode valve metal base having a dielectric oxide layer on the surface, a semiconductor layer and a conductor layer mainly composed of lead dioxide and lead sulfate are sequentially formed to form a laminate. 1. A method for manufacturing a wound solid electrolytic capacitor, comprising: manufacturing a solid electrolytic capacitor, and then spirally winding the laminate. (2) The method for manufacturing a wound solid electrolytic capacitor according to claim (1), wherein the dielectric oxide layer is made of an oxide of an anode valve metal. (3) The winding according to claim (1), wherein the semiconductor layer mainly composed of lead dioxide and lead sulfate is a layer chemically precipitated from a reaction mother liquor containing lead ions and persulfate ions. A manufacturing method for type solid electrolytic capacitors. (4) The concentration of lead ions in the reaction mother liquor ranges from 0.1 mol/l to the concentration that provides saturation solubility, and the persulfate ions range from 0.05 mol/l to 5 mol/l per mol of lead ions.
A method for manufacturing a wound solid electrolytic capacitor according to claim (3), wherein the amount is up to molar. (5) The semiconductor layer contains 10% by weight or more of lead dioxide.
A method for manufacturing a wound solid electrolytic capacitor according to claim (1), wherein the amount is less than % by weight.