JP3208875B2 - Chip-shaped solid electrolytic capacitor and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-shaped solid electrolytic capacitor and a method for producing the same.

[0002]

2. Description of the Related Art As electronic devices have become lighter and thinner, there has been a demand for miniaturization of solid electrolytic capacitors which are one type of electronic components used in such devices. The chip shape meets the demand for miniaturization.

FIG. 1 is a perspective view showing a conventional chip-shaped solid electrolytic capacitor, in which a plurality of solid electrolytic capacitor elements 2 inside an exterior resin 5 are arranged in the same direction. The anode portion 3 and the bottom surface of the conductor layer forming portion 4 formed on the surface of the element are respectively formed by a convex portion 1a which is an anode lead lead portion and a cathode lead lead portion of a pair of opposingly arranged lead frames. Convex part 1b
In a state of being mounted on and joined together, and sealed by a separately prepared exterior resin 5 such as an epoxy resin.

[0004]

The conductor layer forming portion of the above-described capacitor element has a structure in which a semiconductor layer and a conductor layer are laminated on the surface of an anode substrate such as an aluminum foil.
It is thicker than the anode. Therefore, the difference in thickness becomes more remarkable when a plurality of the capacitor elements are stacked, for example, when the conductor layer forming portions are overlapped, and a gap is generated between the anode portions.

[0005] In order to prevent the existence of such a gap, it is conceivable to insert a spacer having the same thickness as that of the gap. However, it is difficult to sufficiently connect the spacer and the anode part. When this is done, the exterior resin enters the gap between the spacer and the anode part, and as a result, there is a problem that the leakage current of the manufactured solid electrolytic capacitor is increased.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, provided a notch at one corner of the anode of each capacitor element,
A metal plate was inserted so as to extend to a part of the notch, and the notch was filled with a conductive material, laminated, and connected. It led to.

That is, the gist of the present invention is that one end of a flat plate-shaped anode substrate having a dielectric oxide film on its surface is used as an anode portion, and the remaining portion of the anode substrate is the dielectric oxide film layer The anode portion and the conductor layer forming portion of a plurality of solid electrolytic capacitor elements having a conductor layer forming portion having a semiconductor layer formed thereon and a conductor layer formed thereon are respectively laminated and connected to lead terminals. In a solid electrolytic capacitor sealed and molded with an exterior resin, there is a cutout at one corner of the anode of each of the solid electrolytic capacitor elements, between the anode and the anode and between the anode and the lead terminal. A metal plate extending to a part of the notch portion is inserted therein, the anode portion and the metal plate are electrically connected, and the notch portion is filled with a conductive material. For solid electrolytic capacitors And a chip solid electrolytic capacitor outer periphery of the stacked the anode portion is covered with a conductive paste.

Further, at one end of an anode substrate made of a valve-shaped metal having a dielectric oxide film layer on its surface,
A solid electrolytic capacitor element having an anode portion having a notch in one corner, a semiconductor layer formed on the dielectric oxide film layer of the remainder of the anode substrate, and a conductor layer formed thereon to have a conductor layer forming portion; After joining a metal plate extending to a part of the notch portion to the anode portion, a plurality of these elements are stacked so that the notch portion overlaps, and the notch portion is filled with a conductive material, and the anode is filled with a conductive material. A method for producing a chip-shaped solid electrolytic capacitor in which lead terminals are connected to a metal plate of the portion and the conductor layer forming portion and sealed and molded with an exterior resin, and an outer peripheral portion of an anode portion of the laminated solid electrolytic capacitor element Is covered with a conductive paste and then sealed with an exterior resin.

Hereinafter, the present invention will be described in detail. As the anode substrate having a valve action used as the anode of the solid electrolytic capacitor in the present invention, any metal having a valve action such as aluminum, tantalum, and alloys using these as a substrate can be used. Examples of the shape of the anode substrate include a flat aluminum foil and plate.

[0010] The dielectric oxide film layer provided on the surface of the anode substrate may be an oxide layer of the valve action metal itself provided on the surface portion of the valve action metal, or may be provided on the surface of the valve action metal foil. May be a layer of another dielectric oxide, but is particularly preferably a layer made of an oxide of the valve metal itself.

In the present invention, the anode is provided in one section of the end of the plate-shaped anode base having the dielectric oxide film layer formed on the surface, and the notch is provided in one corner of the anode. Is important.

The notch may be provided before or after the formation of the dielectric oxide film layer on the anode substrate, or before or after the formation of a semiconductor layer or a conductor layer as described later.

The size of the notch is the size of the anode,
Since it depends on the number of stacked anode substrates, it is determined by preliminary experiments. The shape of the notch may be any known shape such as a semicircle or a square. The number of notches may be plural.

Examples of the material of the metal plate to be used include iron, nickel and alloys containing these metals as main components, and the thickness thereof should be approximately equal to the thickness of the semiconductor layer and the conductor layer described later. Is preferably determined by preliminary experiments, but usually a metal foil of 0.05 mm to 1 mm is used. The size of the metal plate is larger than the size of the anode portion, and reaches only a part of the cutout portion, and is designed so as not to come into contact with the conductor layer forming portion of the capacitor element. The joining between the anode part and the metal plate is performed by welding or the like.

Next, a semiconductor layer is formed on the remaining dielectric oxide film layer except for the anode portion, but the type of the semiconductor layer is not particularly limited, and a conventionally known semiconductor layer can be used. In particular, a semiconductor layer composed of lead dioxide or lead dioxide and lead sulfate, which was filed by the applicant of the present invention (JP-A-62-2
No. 56423, JP-A-63-51621)
However, it is preferable because the high frequency performance of the manufactured solid electrolytic capacitor is good.

Further, a method of forming a complex of tetrathiotetracene and chloranil as a semiconductor layer (Japanese Patent Application Laid-Open No. Sho 62-62)
No. 29123) and a method of chemically depositing thallium oxide as a semiconductor layer from a reaction mother liquor containing thallium ions and persulfate ions (JP-A-62-38715).
Is an example of this.

On the semiconductor layer, a conductive layer is formed by laminating a conventionally known conductive paste such as a carbon paste and / or a silver paste to form a conductive layer forming portion. In addition, the insulating resin layer may be formed in a spiral shape by the insulating resin layer at the boundary between the above-described anode portion, the semiconductor layer, and the conductor layer.

Next, a method of laminating a plurality of capacitor elements formed up to the conductor layer in the same direction will be described. FIG. 2 is a cross-sectional view showing a state in which the laminated capacitor elements are joined by a conductive material 6. In the same figure, after placing each capacitor element so that the notch 7 of the anode part 3 of the capacitor element 2 coincides, injecting so as to fill the notch 7 with the conductive material 6, and further drying and curing. To form a laminated capacitor element. If most of the notch 7 is filled with the conductive material 6,
There may be an unfilled portion of the conductive material 6 in a part of the cutout portion 7.

In the laminated capacitor element, in order to further strengthen the connection between the respective capacitor elements 2, only the conductor layer forming portion of each capacitor element is immersed in a conductive material bath such as a silver paste and dried and hardened. By doing so, integration may be measured. Examples of the conductive material include a known conductive paste such as a silver paste and a fusible metal such as cream solder.

FIG. 1 is a perspective view showing a state where the above-mentioned laminated capacitor element is mounted on a lead frame and connected to a lead terminal. The bottom of the conductor layer forming portion 4 of the laminated capacitor element 2 and the metal plate 8 are mounted on the protrusions 1b and 1a of the lead frame, respectively, and are electrically and mechanically connected by a conductive paste or the like.

The solid electrolytic capacitor element connected to the lead frame in this way is sealed with a transfer molding machine or the like using an exterior resin 5 such as an epoxy resin, and then the protrusion of the lead frame is connected to the capacitor element. It is cut in the vicinity to form a chip-shaped solid electrolytic capacitor.

[0022]

A notch is provided at one corner of the anode of the capacitor element, a metal plate extended to a part of the notch is placed and joined to the anode, and then the capacitor elements are stacked in the same direction. Since the notch portion of the capacitor element is joined by filling it with a conductive material, the joining between the anode portion and the metal plate is improved, and the gap between the anode portions is reduced.

[0023]

The present invention will be described below in more detail with reference to Examples and Comparative Examples.

Examples 1-3 Small pieces of aluminum etching foil (hereinafter referred to as chemical conversion foil) of 45 μF / cm ² having a dielectric oxide film layer formed on the surface by chemical conversion treatment in an aqueous solution of phosphoric acid and ammonium phosphate. 5 mm x 3 mm was prepared. 2mm x 3mm from the end of this chemical foil
Was used as an anode, and cutouts having the shapes and sizes shown in Table 1 were provided.

On the other hand, a nickel foil having a thickness of 0.1 mm and a size shown in Table 1 was prepared as a metal plate, and the tip of the nickel foil was aligned with the tip of the anode portion having no notch, and the layer was formed. The anode part of the foil and the metal plate were connected by spot welding. The remaining 3 mm × 3 mm portion excluding the anode part of the chemical conversion foil was immersed in a mixture of an aqueous solution of lead acetate trihydrate 2.4 mol / l and an aqueous solution of ammonium persulfate 4.0 mol / l, 60
This was left at 20 ° C. for 20 minutes to form a semiconductor layer composed of lead dioxide and lead sulfate.

After such an operation was performed three times, a carbon paste and a silver paste were sequentially laminated on the semiconductor layer to form a conductor layer, thereby producing a capacitor element. Four such capacitor elements were stacked in the same direction, and the conductor layer forming portion of the capacitor element was immersed in a silver paste bath and dried and cured to integrate the conductor layer forming portion.

Next, the bottom portion of the conductor layer forming portion of the multilayer capacitor element and the lowermost metal plate of the anode portion are placed on each of the separately provided pair of protrusions of a lead frame having a protrusion having a width of 3 mm, The anode portion was electrically and mechanically connected by filling the cutout portion with silver paste and attaching the silver paste to the bottom of the conductor layer forming portion. Then, transfer molding was performed using an epoxy resin to produce a chip-shaped solid electrolytic capacitor. Examples 4 to 6 In Examples 1 to 3, the metal plate was made of 42 alloy, and the semiconductor layer was immersed in a 2.0 mol / l aqueous solution of lead acetate trihydrate to form a platinum foil. Chip-shaped solid electrolytic capacitors were produced in the same manner as in Examples 1 to 3, except that lead dioxide electrochemically formed between the cathode and the cathode was used.

COMPARATIVE EXAMPLE 1 A chemical conversion foil and a metal plate having no cutout in the anode portion were used, except that four chemical conversion foils and a metal plate were alternately overlapped, and the anode portion and the metal plate were spot-welded at once. Are Examples 1 to
In the same manner as in Example 3, a chip-shaped solid electrolytic capacitor was produced.

[0029]

[Table 1]

Table 2 shows the performance of the solid electrolytic capacitor immediately after being manufactured as described above. In each example or comparative example, all numerical values are average values of 50 points.

[0031]

[Table 2]

[0032]

The chip-shaped solid electrolytic capacitor of the present invention uses a metal plate as a spacer between the anode portions of the anode substrate, and has a notch at one corner of the anode portion. Since it is extended and inserted to a part of the part, and it is joined with a conductive material through the notch,
The manufactured solid electrolytic capacitor has a good leakage current value.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which laminated capacitor elements are mounted on a lead frame and connected.

FIGS. 2A and 2B are a cross-sectional view and a plan view showing a state in which the laminated capacitor elements are joined by a conductive material.

FIG. 3 is a perspective view showing a conventional multilayer chip solid electrolytic capacitor.

[Explanation of symbols]

 1a Lead frame convex portion 1b Lead frame convex portion 2 Capacitor element 3 Anode portion 4 Conductive layer forming portion 5 Outer resin 6 Conductive material 7 Notch portion 8 Metal plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01G 9/012 H01G 9/04 H01G 9/048

Claims (4)

(57) [Claims] 1. An end portion of an anode substrate made of a valve-shaped metal having a dielectric oxide film layer on the surface is used as an anode portion, and a semiconductor layer is formed on the remaining dielectric oxide film layer of the anode substrate. The anode portions and the conductor layer forming portions of a plurality of solid electrolytic capacitor elements having a conductor layer forming portion having a conductor layer formed thereon are respectively laminated and connected to lead terminals, and are provided with an exterior resin. In the sealed solid electrolytic capacitor, there is a notch at one corner of the anode part of each solid electrolytic capacitor element, between the anode part and the anode part and between the anode part and the lead terminal. , Extended to a part of the cutout portion, the same degree as the conductive layer forming portion
A chip-shaped solid electrolytic capacitor, wherein a metal plate having a thickness of 3 mm is inserted and the anode portion and the metal plate are electrically connected to each other, and a cutout portion is filled with a conductive material. 2. The solid electrolytic capacitor according to claim 1, wherein an outer peripheral portion of the laminated anode portion is covered with a conductive paste. 3. An anode base having a notch at one corner is provided at one end of a flat plate-shaped anode base having a dielectric oxide film layer on its surface and made of a valve action metal. semiconductor layer on the dielectric oxide film layer, a solid electrolytic capacitor element having a conductor layer forming unit to form a conductive layer thereon, said anode portion and extended to a part of the notch, the conductive After joining a metal plate having a thickness similar to that of the body layer forming portion , a plurality of these elements are stacked so that the cutout portions overlap, and the cutout portion is filled with a conductive material, and the metal plate of the anode portion and A method for manufacturing a chip-shaped solid electrolytic capacitor, characterized in that a lead terminal is connected to the conductor layer forming portion and sealed with an exterior resin. 4. The method for producing a chip-shaped solid electrolytic capacitor according to claim 3, wherein an outer peripheral portion of an anode portion of the stacked solid electrolytic capacitor elements is covered with a conductive paste and then sealed with an exterior resin.