JPH0613269A - Multilayer solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a solid electrolytic capacitor excellent in leak current characteristics when sheathing resin of low cost is used, by forming a laminate by mutually fixing two solid electrolytic capacitor elements to be in a fan type by using conductive paste, and sealing the laminate by using sheathing resin. CONSTITUTION:The end portion of an anode base body 1 composed of valve action metal on a flat plane having a dielectric oxide film layer 2 on the surface is made an anode part 5. In a solid electrolytic capacitor element 6, a semiconductor layer 3 and a dielectric layer 4 are formed in order on the dielectric oxide film layer 2 except the anode part 5. The anode parts 5 of two solid electrolytic capacitor elements 6 are arranged so as to face each other. A laminate is formed by fixing the solid electrolytic capacitor elements 6 to be in a fan type by using conductive paste, and is sealed by using sheathing resin 9 Thereby the increase of leak current of a solid electrolytic capacitor which leak current is due to the curing of the sheathing resin 9 can be prevented, and the yield of leak current characteristics can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor, and more particularly to a laminated solid electrolytic capacitor.

[0002]

2. Description of the Related Art In recent years, with the increase in reliability and performance of electronic parts, solid electrolytic capacitors which have good temperature characteristics without using liquid and have small impedance even in a high frequency range are required in the field of capacitors. There is. Under such circumstances, solid electrolytic capacitors using a low resistance material as a semiconductor layer have been widely studied because they meet such requirements.

As an example of the solid electrolytic capacitor described above,
The anode substrate to be used has a wound shape (for example, Japanese Patent Laid-Open No. 62-200719), a flat plate laminated shape (for example, Japanese Patent Laid-Open No. 64-46914), and the like. Among these, the applicant of the present application filed a Japanese Patent Application No. 2-205363 for a method of manufacturing a flat plate laminated shape. According to this manufacturing method, a laminated solid electrolytic capacitor having an extremely high efficiency as compared with the conventional one is obtained.

[0004]

However, in the case of the above-mentioned laminated base body of the anode, if the produced solid electrolytic capacitor is sealed with a resin to coat it, in the case of an exterior resin such as epoxy resin, the resin of the capacitor is cured as the resin is cured. The leakage current characteristic was sometimes deteriorated. Especially, it was remarkable in the case of the non-low stress type resin in which the cost of the exterior resin is low.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a solid electrolytic capacitor having good leakage current characteristics even when an inexpensive exterior resin is used.

[0006]

The present invention has been made in order to achieve the above object, and its gist is to provide an anode substrate made of a flat valve metal having a dielectric oxide film layer on the surface thereof. An end portion serves as an anode portion, and a semiconductor layer is formed on the dielectric oxide film layer excluding the anode portion, and the anode portion of two solid electrolytic capacitor elements in which a conductor layer is sequentially formed thereon are opposed to each other. The solid electrolytic capacitor elements are fixed to each other with a conductive paste in a divergent manner to form a laminated body, and the laminated body is sealed with an exterior resin.

The present invention will be described in more detail below. As the valve action metal used in the present invention, any metal having a valve action such as aluminum, tantalum, niobium, titanium and alloys having these as a substrate can be used. The shape of the anode substrate made of the valve metal is flat, and the surface may be etched. A known method such as electrochemical etching is used as the etching method.

The dielectric oxide film layer formed on the anode substrate may be an oxide film layer of the valve metal itself, or an oxide film layer of another dielectric provided on the flat valve metal. However, an oxide film layer made of an oxide of the valve metal itself is preferable. In any of the above cases, a conventionally known method such as an anodization method using an electrolytic solution can be used as a method for forming the oxide film layer.

Next, a semiconductor layer is formed on the dielectric oxide film layer, and one section of the end portion of the anode substrate on which the dielectric oxide film layer is formed is provided as an anode section, or a part of this section is provided. Connect the anode lead and leave it as the anode part. Then, the semiconductor layer forms a semiconductor layer on the dielectric oxide film layer except for those portions used as the anode portion. Further, a resin layer portion may be formed in a spiral shape with an insulating resin at an interface between the anode portion and a portion where a semiconductor layer described later is formed.

The composition of the semiconductor layer used in the present invention and the method for producing the same are not particularly limited, but in order to improve the performance of the capacitor, the semiconductor layer containing lead dioxide and lead sulfate as main components disclosed by the applicant of the present application. By a chemical deposition method (JP-A-63-51621) or a method of forming a semiconductor layer containing lead dioxide as a main component by an electrochemical deposition method (JP-A-62-185307).
Is preferably used. Further, a method of forming a conductive polymer compound as a semiconductor layer (Japanese Patent Laid-Open No. 60-37114) and a method of chemically depositing thallium oxide as a semiconductor layer from a reaction mother liquor containing thallium ions and persulfate ions. (Japanese Patent Laid-Open No. 62-38715) is also an example.

The conductor layer formed on the surface of the semiconductor layer is formed by a known method such as a method of repeatedly coating and solidifying one or more kinds of conductive paste, a plating method, a metal deposition method, or the like. Further, as the conductive paste, a known powder containing metal powder, carbon powder, or an insulating polymer as a main component can be adopted.

Next, a laminated solid electrolytic capacitor is manufactured by using two solid electrolytic capacitor elements each having a conductor layer formed as described above. 1 to 3 show an example of the laminated solid electrolytic capacitor of the present invention. FIG. 1 is a sectional view of one solid electrolytic capacitor element. In the figure, a dielectric oxide film layer 2 is formed on the surface of a flat anode substrate 1.
Is formed, and the anode part 5 is provided at the end.
The semiconductor layer 3 and the conductor layer 4 are sequentially formed on the portion excluding the anode portion 5. It should be noted that the anode part 5 may have a size and a shape such that external leads can be mechanically and electrically connected as shown in FIG. 4 described later, and as shown in FIG. The U-shaped portion may not be all the anode portion and may be, for example, only one surface.

FIGS. 2 and 3 show a state in which the two solid electrolytic capacitor elements 6 shown in FIG. 1 are arranged in the same direction so that the anode portions 5 face each other and are laminated and fixed by the conductive paste 7. FIG. In the laminated solid electrolytic capacitor of the present invention, the two solid electrolytic capacitor elements 6 are fixed to each other with the conductive paste 7. However, the conductive paste 7 of the element 6 is spread so as to spread from one end to the other end of the element 6. It is important to fill the space and fix it.

In FIG. 2, the conductive paste 7 is filled from the anode part 5 toward the other end in a divergent shape, and conversely in FIG. 3, the conductive paste 7 is spread from the other end toward the anode part 5 in a divergent shape. 7 is filled. Next, as an example of the laminated and fixed solid electrolytic capacitor element, the external lead 8 is connected as shown in the cross section of FIG. 4, and a part of the external lead is removed, and the external resin 9 is sealed to form a laminated solid electrolytic capacitor. There is.

[0015]

In the laminated solid electrolytic capacitor of the present invention, since two solid electrolytic capacitor elements are laminated in a divergent shape, it is considered that the solid electrolytic capacitor functions to relieve the curing stress of the resin when sealed by the exterior resin. . Therefore, it is possible to prevent the leakage current of the solid electrolytic capacitor from increasing due to the hardening of the exterior resin.

[0016]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Examples 1 to 5 and Comparative Example 1 A surface having an alumina dielectric oxide film layer and a thickness of 90 μm.
m, length 5 mm, width 3 mm of the upper end of the aluminum etching foil having a length of 2 mm and a width of 3 mm was used as an anode part, and the remaining 3 mm × 3 mm part was separately prepared lead acetate trihydrate 2.4 mol / 1 aqueous solution and an aqueous solution of ammonium persulfate 4.0 mol / l were immersed and reacted at 60 ° C. for 30 minutes. Such a reaction was repeated three times to form a semiconductor layer composed of 25 wt% lead dioxide and 75 wt% lead sulfate.

Next, a carbon paste tank and a silver paste tank were sequentially dipped and solidified to form a conductor layer on the semiconductor layer, to fabricate a solid electrolytic capacitor element. Two such elements were arranged in the same direction as shown in FIG. 2 and immersed in a silver paste bath to be laminated and fixed. Table 1 shows the measured values of the distance between the two elements at the tip of the element and the distance between the two elements at the center of the element, in order to show the spread state between the layers of the elements that are laminated and fixed and the amount of conductive paste. Indicated. Continuing,
Both protrusions (width: 3 m) of a lead frame (thickness: 0.1 mm, material: 42 alloy) used as a separately prepared external lead
Part of the conductor layer portion of the element laminated and fixed to m) was connected to the anode portion and molded with an epoxy resin (non-low stress type) to produce a solid electrolytic capacitor.

Examples 6 to 10 and Comparative Example 2 The semiconductor layer of the mixture of lead dioxide and lead sulfate used in Examples 1 to 5 was prepared according to the method of Example 3 described in JP-A-60-37114. In place of the conductive polymer semiconductor layer, the two elements were laminated in a manner such that the amount of conductive paste at the tip of the element was reduced as shown in FIG. Solid electrolytic capacitors were produced in the same manner as in Examples 1 to 5.

Table 1 also shows the average initial characteristics of each of the 20 points of the solid electrolytic capacitors produced above. As a result, it is clear that the solid electrolytic capacitor in which two elements are laminated and fixed by the conductive paste in a divergent manner has a good yield of leakage current characteristics.

[0020]

[Table 1]

[0021]

EFFECTS OF THE INVENTION The laminated solid electrolytic capacitor according to the present invention has good leakage current characteristics because the two elements are laminated and fixed by the conductive paste in a divergent manner.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a solid electrolytic capacitor element.

FIG. 2 is a cross-sectional view showing an example of a stacked state of two elements.

FIG. 3 is a cross-sectional view showing an example of a stacked state of two elements. It is a side view.

FIG. 4 is a cross-sectional view showing an example of an exterior state.

[Explanation of symbols]

 1 Anode Base 2 Dielectric Oxide Film Layer 3 Semiconductor Layer 4 Conductor Layer 5 Anode Part 6 Solid Electrolytic Capacitor Element 7 Conductive Paste 8 External Lead 9 Exterior Resin

Claims (1)

[Claims] 1. A semiconductor layer is formed on the dielectric oxide film layer at a portion excluding the anode part by using an end of an anode base made of a flat valve metal having a dielectric oxide film layer on the surface as an anode part. , The anode portions of two solid electrolytic capacitor elements on which conductive layers are sequentially formed are arranged so as to face each other, and the solid electrolytic capacitor elements are fixed to each other with a conductive paste in a divergent shape to form a laminated body. The laminated solid electrolytic capacitor is characterized in that the laminated body is sealed with an exterior resin.