JPH07183167A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a solid electrolytic capacitor having a good moisture resisting ability by constituting the anode sections of capacitor elements of metallic wires and connecting the metallic wires to anode leading sections. CONSTITUTION:Each capacitor element 5 is constituted in such a way that a dielectric oxide film layer 2 is formed on the surface of valve-action metallic foil 1 and a metallic wire 11 is connected to the foil 1, and then, an insulating material 12 is applied to the connection of the wire 11 with the foil 1. In addition, a semiconductor layer 3 and conductor layer 4 are successively formed on the layer 2. The anode section (metallic wire 11) and cathode section of the element 5 thus constituted are respectively put on an anode lead section 6a and cathode lead section 6b of a lead frame 6 and the anode section is connected to the section 6a by welding, conductive past, soldering, etc., and the cathode section is connected to the section 6b by using such a conductive material as conductive paste, solder, etc. Therefore, intrusion of moisture into the layer 2 through the lead frame 6 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor.

[0002]

2. Description of the Related Art A conventional chip-shaped solid electrolytic capacitor is
As shown in FIGS. 5 and 6, a semiconductor is formed on the surface of a flat metal foil 1 made of a valve metal such as aluminum, tantalum, niobium, etc. having a dielectric oxide film layer 2 on the surface except for a part serving as an anode part. A solid electrolytic capacitor element 5 (hereinafter referred to as a capacitor element) in which the layer 3 and the conductor layer 4 are sequentially laminated is formed, and then this capacitor element 5 is connected to the lead frame 6, but two convex portions of the lead frame 6 are formed. 6
a and 6b are opposed to each other with a space, and each convex portion 6
a and 6b have an anode part 7 and a cathode part 8 of the capacitor element 5.
Is placed.

The former is a welding 9 or the like, and the latter is a conductive material 10 such as silver paste or the like, and the projections 6a, 6 of the lead frame 6 are formed.
After being electrically and mechanically connected to b, it is sealed with the exterior resin 13 to form a chip solid electrolytic capacitor. The sealed solid electrolytic capacitor is required to satisfy electric performance such as capacity, and further, a product is one that has passed a sampling test such as a load test and a moisture resistance test.

[0004]

In the above-described capacitor element, during the humidity resistance test, moisture enters from the lead frame and approaches the dielectric element near the dielectric oxide film layer of the capacitor element, thereby increasing the capacitance and tan δ value of the manufactured capacitor. There was a drawback that In order to prevent such a defect, it is considered to cover the capacitor element with a water-resistant resin, but it has poor workability and has a cost problem.

[0005]

The present invention has been made to solve the above-mentioned problems, and its gist is to connect a metal wire to a valve action metal foil having a dielectric oxide film layer on its surface. As an anode part, an insulating material is applied to the connection part between the metal wire and the metal foil, and then a semiconductor layer and a conductor layer are sequentially formed on the surface of the metal foil to form a cathode part, and then the anode of the lead frame. A solid electrolytic capacitor manufacturing method is characterized in that the lead-out portion and the cathode lead-out portion are connected to the anode portion and the cathode portion of the capacitor element, respectively, and sealed and molded with an exterior resin.

The present invention will be described in detail below. As the valve action metal foil used in the present invention, for example, a metal foil having a valve action such as aluminum, tantalum, and an alloy using these as a substrate can be used. The actual surface area of the valve metal foil may be increased by etching. The dielectric oxide film layer provided on the surface of the valve action metal foil may be an oxide layer of the valve action metal itself provided on the surface portion of the valve action metal, or on the surface of the valve action metal. It may be another dielectric oxide layer provided, but is preferably a layer made of an oxide of the valve metal itself.

Next, a metal wire is connected to the valve action metal foil thus formed up to the dielectric oxide film layer to form an anode part, and an insulating material is applied to the connection part between the metal foil and the metal wire. After that, a method of forming a semiconductor layer and a conductor layer on the surface of the metal foil in order to form a cathode portion will be described. FIG. 1 is a plan view showing a capacitor element 5 including the cathode portion 8 described above. 2 is a sectional view taken along the line AA ′ of FIG. Figure 1
In FIG. 2, the dielectric oxide film layer 2 is formed on the surface of the valve action metal foil 1, the metal wire 11 is connected, and the insulating material 12 is provided at the connection portion between the metal foil 1 and the metal wire 11. It has been applied. Further, a semiconductor layer 3 and a conductor layer 4 are sequentially formed on the dielectric oxide film layer 2.

As the material of the metal wire 11, a gold wire having a valve action such as aluminum, tantalum, niobium, titanium and alloys having these as substrates can be used. The sectional shape of the metal wire is a circle, an ellipse, a square, or the like. Further, the length and diameter of the metal wire vary depending on the size of the valve metal foil used and the shape of the produced solid electrolytic capacitor, and thus are determined by preliminary experiments conducted in advance.
Further, the conductor oxide film layer may be previously formed on the metal wire by the method described above. The valve action metal foil 1 and the metal wire 11 are connected by welding, conductive paste such as silver paste,
It is connected by one or more methods such as soldering. Further, in the present invention, the insulating material 12 is applied to the connection portion between the valve action metal foil 1 and the metal wire 11, but stress is applied to the opposite side of the connection face between the valve action metal foil 1 and the metal wire 11 during connection. In such a case, it is desirable to apply the insulating material 12 to the surface opposite to the connection surface.

As the insulating material, silicone resin, fluorine resin, epoxy resin, acrylic resin, alkyd resin,
Examples thereof include conventionally known insulating resins such as hydrocarbon resins such as butadiene rubber, phenol resins and urethane resins, and insulating inorganic substances composed of ceramics such as alumina and silica. In the present invention, the metal wire 11 is connected to the valve action metal foil 1 to form the anode part, and the semiconductor layer is formed on the remaining dielectric oxide film layer except a part of the anode part. There is no particular limitation on the type of the above, and conventionally known semiconductor layers can be used.

Among them, among others, a semiconductor layer made of lead dioxide and lead sulfate by the applicant of the present application (JP-A-62-2).
56423, JP-A-63-51621)
However, the high frequency performance of the produced solid electrolytic capacitor is favorable, which is preferable. In addition, a method of forming a complex of tetrathiotetracene and chloranil as a semiconductor layer (Japanese Patent Laid-Open No. 6-58242)
2-29123), and a semiconductor layer made of a conductive polymer compound obtained by doping a hetero five-membered ring polymer compound with a dopant (JP-A-60-37114). On such a semiconductor layer, a conventionally known conductive paste such as carbon paste and / or silver paste is laminated to form a conductor layer to form the cathode portion 8.

Next, a method of connecting the capacitor element having the conductor layer thus formed to the lead frame will be described. 3 and 4 are a plan view and a sectional view showing a state in which the capacitor element 5 is connected to the lead frame 6.
3 and 4, the anode portion 7 of the capacitor element 5
(11 metal wire) and the cathode portion 8 (not shown) are placed on the anode lead lead-out portion 6a and the cathode lead lead-out portion 6b of the lead frame 6, respectively, and the anode portion is welded, conductive paste, solder, etc. On the other hand, the cathode part is connected by a conductive material 10 such as a conductive paste or solder. The capacitor element thus connected to the lead frame is sealed and molded with an exterior resin such as an epoxy resin, leaving a part of the lead frame, to form a solid electrolytic capacitor.

[0012]

Since the anode part of the capacitor element and the lead frame are connected by the metal wire, the penetration of moisture into the dielectric oxide film layer via the lead frame is relieved.

[0013]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Examples 1 to 6 Small pieces of 45 μF / cm ² aluminum etching foil (hereinafter referred to as chemical conversion foil) having a dielectric oxide film layer formed on the surface by chemical conversion treatment in phosphoric acid and ammonium phosphate aqueous solution 3 mm × 3. 0.5 mm was prepared, and the metal wire shown in Table 1 was welded to the center of one end of each piece of the chemical conversion foil. The insulating material shown in Table 1 was applied to the side corresponding to the connection portion and the connection portion on the surface opposite to the connection surface, and then dried and cured. Next, the metal wire and the chemical conversion foil were again placed in phosphoric acid and an ammonium phosphate aqueous solution for chemical conversion treatment to form a dielectric oxide film layer on the surface. Subsequently, a small piece of the chemical foil 3 mm x 3.5 mm was dipped in a mixed solution of a 2.4 mol / l aqueous solution of lead acetate trihydrate and a 4.0 mol / l aqueous solution of ammonium persulfate, and kept at 60 ° C for 2
After standing for 0 minute, a semiconductor layer made of lead dioxide and lead sulfate was formed. After performing such an operation three times, a carbon paste and a silver paste were sequentially laminated on the semiconductor layer to form a conductor layer, and a capacitor element was manufactured. On the other hand, the lead wire (material 42 alloy, solder plating, thickness 0.1 mm) separately prepared for the anode lead lead-out portion and the cathode lead-out portion (width of each lead-out portion 3.0 mm, lead-out interval 1 mm), the metal wire of the anode portion and the cathode The parts were placed, the former was connected by welding and the latter was connected by silver paste. Then, transfer molding was performed using an epoxy resin to produce a chip-shaped solid electrolytic capacitor having external dimensions of 7 mm × 4 mm × 3 mm.

Comparative Example 1 In Example 1, the dimension of the chemical conversion foil was set to 3 mm × 5 mm and 3 m.
A semiconductor layer and a conductor layer are formed on a part of m × 3.5 mm,
A chip solid electrolytic capacitor was produced in the same manner as in Example 1 except that the remaining 3 mm × 1.5 mm portion was connected to the anode lead lead-out portion of the lead frame as the anode portion. Table 2 shows the state of the solid electrolytic capacitor immediately after being manufactured as described above and the performance of the capacitor after a humidity resistance test at 85 ° C. and 85% RH for 200 hours. Each example or comparative example is an average value of all numerical values n = 50 points.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

In the solid electrolytic capacitor of the present invention, since the anode part of the capacitor element is a metal wire and is connected to the anode lead lead-out part, the capacitance and tan δ value after the humidity resistance test are suppressed.

[Brief description of drawings]

FIG. 1 is a plan view of a capacitor element showing an example of the present invention.

FIG. 2 is a sectional view of a capacitor element showing an example of the present invention.

FIG. 3 is a plan view showing a state in which a capacitor element is connected to an anode lead drawer and a cathode lead drawer.

FIG. 4A is a cross-sectional view showing a state in which a capacitor element is connected to an anode lead drawer and a cathode lead drawer. (B) It is sectional drawing of other examples which show the state which connected the capacitor element to the anode lead drawer and the cathode lead drawer.

FIG. 5 is a plan view showing a state in which a conventional capacitor element is placed on a lead frame.

FIG. 6 is a cross-sectional view showing a state in which a conventional capacitor element is placed on a lead frame.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Valve metal foil 2 Dielectric oxide film layer 3 Semiconductor layer 4 Conductor layer 5 Solid electrolytic capacitor element 6a One convex portion of the lead frame (anode lead lead portion) 6b The other convex portion of the lead frame (cathode lead lead portion) ) 7 Anode part 8 Cathode part 9 Welding 10 Conductive material 11 Metal wire 12 Insulation material 13 Exterior resin

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Claims (1)

[Claims] 1. A metal wire is connected to a valve action metal foil having a dielectric oxide film layer on its surface to form an anode part, and an insulating material is applied to the connection part between the metal wire and the metal foil, and then a metal is formed. A semiconductor layer and a conductor layer are sequentially formed on the foil surface to form a cathode part,
Next, a method for producing a solid electrolytic capacitor, characterized in that the anode part and the cathode lead part of the lead frame are connected to the anode part and the cathode part of the capacitor element, respectively, and sealed with an exterior resin.