JPH09246101A - Chip-shaped solid electrolytic capacitor - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: It is possible to improve the durability of the joint portion between the root of the anode lead wire and the anode side electrode layer in a severe thermal shock test, and as a result, it is also excellent in electrical characteristics. It is an object of the present invention to provide a chip-shaped solid electrolytic capacitor which can be obtained. SOLUTION: A thick tin alloy layer 20 is provided on the surface of an anode-side electrode layer 18 formed on an anode lead-out surface 17a of an exterior resin 17 located at the base of an anode lead-out wire 12.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, the number of chip components has been rapidly increasing due to the development of light and thin electronic devices and the development of surface mounting technology. In the chip solid electrolytic capacitor, further miniaturization of the chip component itself is required as the size and capacity of the chip solid electrolytic capacitor are increasing.

The structure of a conventional chip-shaped solid electrolytic capacitor will be described below. FIG. 6 is a perspective view of a conventional chip solid electrolytic capacitor, and FIG. 7 is a vertical sectional view of the chip solid electrolytic capacitor shown in FIG.

In FIGS. 6 and 7, reference numeral 1 denotes a capacitor element, and this capacitor element 1 has an anode lead wire 2 led out from a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal, and A dielectric oxide film, an electrolyte layer, and a colloidal carbon layer are sequentially formed on the surface of a porous anode body by a general method, and then a cathode layer 3 made of silver paint is formed. 4 is a metal layer,
The metal layer 4 is formed by molding using a round silver wire. Then, the metal layer 4 is located on the facing surface 3a of the cathode layer 3 of the capacitor element 1 which faces the lead-out surface of the anode lead-out wire 2, and the paste-like conductive material containing a thermoplastic resin or a thermosetting resin as a main component. The cathode lead-out layer 6 is formed by mounting the adhesive 5 and then thermally curing the paste-like conductive adhesive 5.

Subsequently, the capacitor element 1 including the cathode lead-out layer 6 composed of the metal layer 4 and the conductive adhesive 5 so that the anode lead-out wire 2 is drawn out to one side is resin-molded by transfer molding, and The exterior resin 7 is coated with a resin longer than the length of the finished product, and then a part of the surface of the exterior resin 7 facing the anode lead-out surface 7a of the anode lead-out wire 2 is removed to form the metal layer 4 on the cathode lead-out surface 7b. The cathode lead-out layer 6 is exposed by exposing a part thereof.

Thereafter, the surfaces of the anode lead wire 2, the cathode lead surface 7b, and the exterior resin 7 are blast-polished,
Physically roughen each surface. Then, the anode lead wire 2 is cut to a predetermined size, and after that, it is degreased with an alkaline solution having a pH of 10 to 12, and then the surface of the exterior resin 7 that has been physically roughened by the blasting is chemically treated with an etching solution. After roughening the surface, a catalyst of palladium, which is a pretreatment for electroless plating, is applied, and then the anode lead wire 2
In order to form a nickel film on the surface of the exterior resin 7 including the cathode lead-out layer 6 and the cathode lead-out layer 6, it is immersed in an electroless nickel plating solution for about 2 minutes.
Electrode formation is performed after electroless plating of μm, and nickel and solder of about 8 to 10 μm are formed by electrolytic plating in order to secure soldering of portions that will be external electrode terminals, and the anode side electrode layer 8 and the cathode side electrode layer 9
Was composed.

[0007]

However, according to the structure of the conventional chip-shaped solid electrolytic capacitor described above,
Since the coating is a composite of electroless plating and electrolytic plating, the overall main surface has a uniform plating thickness of about 10 to 12 μm, but the root angle between the anode lead-out wire 2 and the anode lead-out surface 7a is almost right. The root portion 10 can obtain only a plating film thickness of about 5 to 6 μm as compared with the main surface portion. That is, the root portion 10 has a thickness that is about ½ of the plating thickness on the main surface due to the variation in the deposition of electrolytic plating. This thinness of the plating thickness is caused by the fact that the angle between the anode lead-out wire 2 and the anode lead-out surface 7a is substantially right, so that the root portion 10 is not sufficiently deposited by electrolytic plating and the plating film thickness is thin. It is what is done. In this way, a finished product in which the angle of the root portion 10 is substantially right and the joint portion between the anode lead-out wire 2 and the anode lead-out surface 7a has a thin plating film thickness is mounted on a printed circuit board,
When a harsh thermal shock test is carried out, stress due to thermal strain is concentrated on the root portion 10, and this stress concentration causes deterioration of the plating film, causing a problem of characteristic deterioration.

The present invention solves the above-mentioned conventional problems, and can improve the durability of the joint between the root of the anode lead wire and the anode-side electrode layer in a severe thermal shock test. An object of the present invention is to provide a chip-shaped solid electrolytic capacitor having excellent electric characteristics.

[0009]

In order to achieve the above object, the chip solid electrolytic capacitor of the present invention is a dielectric oxidation of an anode body made of a valve metal having an anode lead wire embedded so that one end is exposed. A capacitor element formed by providing a coating film, an electrolyte layer and a cathode layer, and a cathode derivation layer provided on a surface facing the extraction surface of the anode derivation line of this capacitor element and comprising a metal layer and a conductive adhesive, Exterior resin covering the capacitor element and the cathode derivation layer so that a part of the anode derivation line and the metal layer are exposed, and an anode side electrode layer formed on the anode derivation surface and the cathode derivation surface of the exterior resin, and A cathode side electrode layer is provided, and a thick tin alloy layer is provided on the surface of the anode side electrode layer formed at the base of the anode lead wire and formed on the anode lead surface of the exterior resin.
According to this configuration, it is possible to improve the durability of the joint between the root of the anode lead wire and the anode-side electrode layer in the severe thermal shock test, and thereby, the excellent electrical characteristics can be obtained. It is a thing.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a dielectric oxide film, an electrolyte layer, and a cathode layer are formed on an anode body made of a valve metal in which an anode lead wire is embedded so that one end is exposed. A capacitor element formed by providing a cathode lead layer formed on the surface of the capacitor element that faces the lead surface of the anode lead wire, the cathode lead layer including a metal layer and a conductive adhesive, and the anode lead wire and the metal layer. Of the exterior resin that covers the capacitor element and the cathode lead-out layer so that a part of the outer surface of the package is exposed, and the anode-side electrode layer and the cathode-side electrode layer formed on the anode lead-out surface and the cathode lead-out surface of the exterior resin. The thick tin alloy layer is provided on the surface of the anode side electrode layer formed on the anode lead surface of the exterior resin located at the base of the anode lead wire. According to this configuration, the thick tin alloy layer is provided. The presence of said anode Since it is possible to increase the joint area of the joint portion between the root portion of the outgoing line and the anode-side electrode layer, the fatigue fracture durability of the joint portion in the thermal shock test becomes excellent, and as a result, also in the electrical characteristics. It is an excellent product.

According to a second aspect of the present invention, a capacitor element is formed by providing a dielectric oxide film, an electrolyte layer and a cathode layer on an anode body made of a valve metal having an anode lead wire embedded so that one end is exposed. And a cathode lead-out layer which is provided on the surface of the capacitor element facing the lead-out surface of the anode lead-out line and which is composed of a metal layer and a conductive adhesive, and a part of the anode lead-out line and the metal layer. As described above, including the exterior resin covering the capacitor element and the cathode lead-out layer, and the cathode side electrode layer formed on the cathode lead-out surface of the exterior resin, and a thick resin layer at the root of the anode lead-out line in the exterior resin And the anode side electrode layer is formed on the anode lead-out surface of the exterior resin so as to cover the thick resin layer. According to this configuration, the presence of the thick resin layer causes the anode side electrode layer and the positive electrode layer Since the joint with the lead-out wire will form a rounded corner, the structure will disperse the stress of the joint even when subjected to the thermal strain of the thermal shock test. Since the fatigue fracture resistance of the portion is also excellent, excellent electric characteristics can be obtained.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view of a chip solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a vertical sectional view of the chip solid electrolytic capacitor shown in FIG.

In FIG. 1 and FIG. 2, reference numeral 11 denotes a capacitor element, and this capacitor element 11 has an anode lead wire 12 led out from a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal. A dielectric oxide film, an electrolyte layer, and a colloidal carbon layer are sequentially formed on the surface of a porous anode body by a general method, and then a cathode layer 13 made of silver paint is formed. Reference numeral 14 is a metal layer, and this metal layer 14 is formed by molding using a silver wire extended in a circular shape. Then, the metal layer 14 is located on the facing surface 13a of the cathode layer 13 of the capacitor element 11 that faces the lead-out surface of the anode lead-out wire 12, and the paste-like conductivity containing a thermoplastic resin or a thermosetting resin as a main component. Attach with adhesive 15, then
The cathode lead-out layer 16 is formed by heat-curing the paste-like conductive adhesive 15.

Subsequently, the capacitor element 11 including the cathode lead-out layer 16 composed of the metal layer 14 and the conductive adhesive 15 so that the anode lead-out wire 12 is drawn out to one side is resin-molded by transfer molding, and The exterior resin 17 is covered with an exterior resin longer than the length of the finished product, and then a part of the surface of the exterior resin 17 facing the anode lead-out surface 17a of the anode lead-out wire 12 is removed to form a metal layer 1 on the cathode lead-out surface 17b.
4 is exposed to expose the cathode lead layer 16.

After that, the anode lead wire 12 and the cathode lead surface 17
By blasting the surfaces of b and the exterior resin 17, the respective surfaces are physically roughened. Then, the anode lead wire 12 is cut to a predetermined size, and then PH10
After degreasing with an alkaline solution of 12, the surface of the exterior resin 17 that has been physically roughened by the blasting is further chemically roughened with an etching solution, and then a pretreatment for electroless plating is performed. After applying a catalyst of palladium, and then immersing it in an electroless nickel plating solution to form a nickel coating on the surface of the exterior resin 17 including the anode lead wire 12 and the cathode lead layer 16 and performing electroless plating of about 2 μm, About 8 to 10 electrodes are formed by electrolytic plating to selectively form electrodes and to secure soldering to the parts that will be external electrode terminals.
Anode side electrode layer 1 by forming nickel and solder of μm
8 and the cathode side electrode layer 19 are formed.

Next, a thick tin alloy layer 20 was provided on the surface of the anode electrode layer 18 by melting it with cream solder or rod-shaped solder at the root of the anode lead wire 12. By providing this thick tin alloy layer 20, the joint area between the anode-side electrode layer 18 and the root of the anode lead-out wire 12 can be increased, and therefore the durability of fatigue fracture in the thermal shock test of the joint is excellent. As a result, excellent electrical characteristics can be obtained.

Next, another embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a perspective view of a chip solid electrolytic capacitor according to another embodiment of the present invention, and FIG. 4 is a vertical sectional view of the chip solid electrolytic capacitor shown in FIG.

In FIGS. 3 and 4, reference numeral 21 is a capacitor element, and this capacitor element 21 leads out an anode lead wire 22 from a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal, and A dielectric oxide film, an electrolyte layer, and a colloidal carbon layer are sequentially formed on the surface of a porous anode body by a general method, and then a cathode layer 23 made of silver paint is formed. Reference numeral 24 is a metal layer, and this metal layer 24 is formed by molding using a silver wire extended in a circular shape. The metal layer 24 is positioned on the facing surface 23a of the cathode layer 23 of the capacitor element 21 that faces the lead-out surface of the anode lead-out wire 22, and the paste-like conductive material containing a thermoplastic resin or a thermosetting resin as a main component. Attach with adhesive 25, then
The cathode lead layer 26 is formed by thermosetting the paste-like conductive adhesive 25.

Subsequently, the capacitor element 21 including the cathode lead-out layer 26 composed of the metal layer 24 and the conductive adhesive 25 so that the anode lead-out wire 22 is drawn out to one side is resin-molded by transfer molding, and The exterior resin 27 having a length longer than the length of the finished product is coated, and then a part of the surface of the exterior resin 27 facing the anode lead-out surface 27a of the anode lead-out wire 22 is removed to remove the metal layer 2 on the cathode lead-out surface 27b.
4 is exposed to expose the cathode lead layer 26.

Next, the anode lead wire 22 and the cathode lead surface 27b.
By blasting the surface of the exterior resin 27, the respective surfaces are physically roughened. Then, the anode lead wire 22 is cut into a predetermined size, and the anode lead wire 2 is cut.
After cutting 2, a thick resin layer 30 made of a liquid insulating resin or a conductive resin made of a thermosetting resin or a thermoplastic resin was formed in a round shape at the base of the anode lead wire 22 in the exterior resin 27. Next, after degreasing with an alkaline solution having a pH of 10 to 12, the surface of the exterior resin 27 that has been physically roughened by blasting is chemically roughened with an etching solution, and then electroless plating is performed. A catalyst of palladium, which is a pretreatment, is applied, and then a nickel coating is applied to form a nickel coating on the surface of the exterior resin 27 including the anode lead wire 22 and the cathode lead layer 26.
m to form the nickel coating film selectively, and in order to secure the soldering of the portions to be the external electrode terminals, nickel of about 8 to 10 μm is formed by electrolytic plating so as to cover the thick resin layer 30. By providing solder and solder, the anode side electrode layer 28 and the cathode side electrode layer 29 are formed on the anode lead-out surface 27a and the cathode lead-out surface 27b of the exterior resin 27. The plating film at the joint between the anode-side electrode layer 28 and the anode lead wire 22 has a thin coating thickness of about 4 to 5 μm, but the joint is formed at the rounded corners, so the thermal shock test is performed. The structure is such that the stress in the joint is dispersed even when subjected to the thermal strain of 1. Due to this, it is possible to obtain excellent fatigue fracture resistance of the joint in the thermal shock test, and as a result, it is also excellent in electrical characteristics. It is what you get.

Based on the above-described embodiment of the present invention and other embodiments, the dimensions of the finished product: 2 × 1.2 ×
1.2 mm size rated capacity: 6v10μF chip solid electrolytic capacitor samples (n = 1)
In addition, the conventional chip-shaped solid electrolytic capacitor having the same structure as the embodiment of the present invention except that the structure of the base of the anode lead wire was changed was prototyped (n = 100).
Then, the results of comparing the initial characteristics of these electrical characteristics with the defective rate are shown in (Table 1), and the trial-produced samples were each prepared by using cream solder on a 1.2 mm-thick glass epoxy substrate (n = 20). FIG. 5 shows the results of surface-mounting and performing a severe thermal shock test {-65 ° C. to + 175 ° C. (each temperature: keep for 5 minutes)} 3000 cycles.

[0022]

[Table 1]

As is clear from (Table 1), the chip-shaped solid electrolytic capacitor of the present invention has a capacitance (Ca) which is an electrical characteristic as compared with the conventional chip-shaped solid electrolytic capacitor.
p), tangent of loss angle (tan δ), leakage current (LC), and defective rate (%) of electrical characteristics are quite comparable.

Further, as is apparent from FIG. 5, the chip-shaped solid electrolytic capacitor of the present invention has a severer thermal shock test (-65 ° C. to +) than the conventional chip-shaped solid electrolytic capacitor.
It is possible to reliably prevent the change of the tangent (tan δ) of the loss angle after 175 ° C. and is excellent in its durability.

The material forming the thick tin alloy layer 20 shown in the embodiment of the present invention is not limited to the tin-lead solder such as cream solder or rod-shaped solder, but other materials. Even when lead-free solder such as tin-silver based or tin-bismuth based alloy is used as the material, the same effect as in the above-described one embodiment can be obtained.

[0026]

As described above, according to the chip-shaped solid electrolytic capacitor of the present invention, the dielectric oxide film, the electrolyte layer, and the electrolyte layer are formed on the anode body made of the valve metal in which the anode lead wire is buried so that one end is exposed. A capacitor element formed by providing a cathode layer, a cathode lead layer provided on a surface facing the lead-out surface of the anode lead wire of the capacitor element, and comprising a metal layer and a conductive adhesive, the anode lead wire, and An exterior resin covering the capacitor element and the cathode derivation layer so that a part of the metal layer is exposed, and an anode side electrode layer and a cathode side electrode layer formed on the anode derivation surface and the cathode derivation surface of the exterior resin. And, since the thick tin alloy layer is provided on the surface of the anode side electrode layer formed on the anode lead-out surface of the exterior resin located at the base of the anode lead-out wire, the root of the anode lead-out wire is provided. The anode side It is possible to increase the joint area of the joint with the electrode layer, which results in excellent fatigue fracture durability of the joint in the thermal shock test, and as a result, excellent electrical characteristics can be obtained. Is.

[Brief description of drawings]

FIG. 1 is a perspective view of a chip solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of the chip solid electrolytic capacitor shown in FIG.

FIG. 3 is a perspective view of a chip solid electrolytic capacitor according to another embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view of the chip solid electrolytic capacitor shown in FIG.

FIG. 5 is a characteristic diagram showing changes in tan δ after a thermal shock test of one embodiment of the present invention, another embodiment and a conventional product.

FIG. 6 is a perspective view showing a conventional chip solid electrolytic capacitor.

7 is a vertical sectional view of the chip solid electrolytic capacitor shown in FIG.

[Explanation of symbols]

 11, 21 Capacitor element 12, 22 Anode lead wire 13, 23 Cathode layer 14, 24 Metal layer 15, 25 Conductive adhesive 16, 26 Cathode lead layer 17, 27 Exterior resin 17a, 27a Anode lead surface 17b, 27b Cathode lead Surface 18,28 Anode side electrode layer 19,29 Cathode side electrode layer 20 minutes thick tin alloy layer 30 minutes thick resin layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Ueoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A capacitor element comprising a dielectric oxide film, an electrolyte layer and a cathode layer provided on an anode body made of a valve metal in which an anode lead wire is embedded so that one end is exposed.
The cathode lead-out layer provided on the surface of the capacitor element facing the lead-out surface of the anode lead-out line and comprising a metal layer and a conductive adhesive, and the anode lead-out line and a part of the metal layer are exposed. An exterior resin covering the capacitor element and the cathode lead-out layer, and an anode-side electrode layer and a cathode-side electrode layer formed on the anode lead-out surface and the cathode lead-out surface of the exterior resin, and at the base of the anode lead-out wire A chip-shaped solid electrolytic capacitor, characterized in that a thick tin alloy layer is provided on the surface of an anode side electrode layer formed on the anode lead-out surface of the exterior resin. 2. A capacitor element comprising a dielectric oxide film, an electrolyte layer and a cathode layer provided on an anode body made of a valve metal in which an anode lead wire is embedded so that one end is exposed,
The cathode lead-out layer provided on the surface of the capacitor element facing the lead-out surface of the anode lead-out line and comprising a metal layer and a conductive adhesive, and the anode lead-out line and a part of the metal layer are exposed. An exterior resin covering the capacitor element and the cathode lead-out layer, and a cathode-side electrode layer formed on the cathode lead-out surface of the exterior resin are provided, and a thick resin layer is provided at the root of the anode lead-out wire in the exterior resin. At the same time, a chip solid electrolytic capacitor is characterized in that an anode-side electrode layer is formed on the anode lead-out surface of the exterior resin so as to cover the thick resin layer.