JPH0620883A - Manufacture of chip-type solid-state electrolytic capacitor - Google Patents

Abstract

PURPOSE:To easily obtain a capacitor which is excellent in mechanical adhesion, where a cathode metal layer is hardly separated off a cathode conductor layer even if thermal stress is applied. CONSTITUTION:The outer surfaces of a capacitive element 11a, a cathode conductor layer 16, and a cathode layer 15 are covered with a sheathing resin layer 19 excluding the tip of an anode lead-out wire 12 and a part of the cathode conductor layer 16, the exposed particles of inorganic metal particles 18 contained in the cathode conductor layer 16 and partially exposed out of the layer 16 are dissolved by etching for the formation of irregularities 16b on the surface of the cathode conductor layer 16, and then a cathode metal layer 21 is formed on the surface of the cathode conductor layer 16.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, the number of chip parts has been rapidly increasing with the progress of light and thin electronic devices and surface mounting technology. In the chip-type 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.

A conventional method for manufacturing a chip-shaped solid electrolytic capacitor will be described below. FIG. 5 shows a cross-sectional view of a conventional chip-shaped solid electrolytic capacitor. In FIG. 5, reference numeral 1 denotes a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal. A dielectric oxide film is formed by anodic oxidation on a part of the anode lead wire 2 made of tantalum wire and the entire surface of the anode body 1, and an electrolyte layer such as manganese dioxide is further formed on this surface. Reference numeral 3 denotes a Teflon plate attached to the anode lead-out wire 2, and this Teflon plate 3 is an insulating plate for preventing manganese nitrate from creeping up and adhering manganese dioxide to the anode lead-out wire 2 during the formation of the electrolyte layer. A cathode layer 4 composed of a carbon layer and a silver coating layer is formed on the electrolyte layer by a dipping method.
Are sequentially laminated to form the capacitor element 1a. Then, a cathode conductor layer 5 made of a silver coating layer is formed on a portion of the capacitor element 1a opposite to the anode lead wire 2 in the cathode layer 4, and then the capacitor element 1a and the cathode conductor layer 5 are formed. The anode lead wire 2 is coated with the exterior resin 6 so as to be drawn out to one side, and then the anode metal layer 9 and the cathode metal layer 10 are formed on the anode lead-out surface 7 and the cathode lead-out surface 8 of the exterior resin 6, respectively. ..

[0004]

However, in such a chip-shaped solid electrolytic capacitor, since the adhesion between the exposed cathode conductor layer 5 and the cathode metal layer 10 formed thereon is weak, the chip-shaped solid electrolytic capacitor is chip-shaped. When the solid electrolytic capacitor is subjected to thermal stress due to repeated immersion in a molten solder bath and insertion into and removal from a far-infrared furnace, there is a problem that the cathode metal layer 10 is easily peeled off to cause a defect.

The present invention solves the above-mentioned conventional problems and provides a capacitor excellent in mechanical adhesion in which the cathode metal layer is not easily peeled off from the cathode conductor layer even when heat stress is applied. It is an object of the present invention to provide a method for manufacturing a chip solid electrolytic capacitor that can be easily obtained.

[0006]

In order to achieve the above object, a method for manufacturing a chip solid electrolytic capacitor of the present invention comprises:
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 in which the anode lead wire is embedded so that one end of the anode lead wire is exposed. A cathode conductor layer containing metal and inorganic particles is formed on the portion of the cathode layer opposite to the anode lead wire, and then the outer surfaces of the capacitor element, the cathode conductor layer and the cathode layer are connected to the anode lead layer. The tip of the wire,
The cathode conductor layer is covered with an exterior resin material except for a part of the cathode conductor layer, and the exposed portion of the exposed metal and inorganic particles contained in the cathode conductor layer is dissolved by etching to form the cathode conductor layer. On the exposed surface of the exterior resin layer, the anode metal layer connected to the anode lead wire is formed on the anode lead-out surface of the exterior resin layer, and on the cathode conductor layer exterior side of the exterior resin layer. A cathode metal layer connected to the cathode layer and the cathode conductor layer is formed.

[0007]

According to the above-mentioned manufacturing method, the cathode conductor layer containing the particles of the metal and the inorganic material is formed in the portion of the cathode layer of the capacitor element opposite to the anode lead-out line, and then the capacitor element and the cathode layer are formed. The outer surface of the anode lead wire is covered with an exterior resin layer excluding a part of the cathode conductor layer, and is further contained in the cathode conductor layer, and exposed metal, a surface of inorganic particles. Since the unevenness is formed on the exposed surface of the cathode conductor layer by dissolving the exposed portion by etching, it is possible to increase the roughness of the surface of the exposed surface of the cathode conductor layer exposed from the exterior resin layer. As a result, by forming a cathode metal layer on the exposed surface of such a cathode conductor layer, an anchor effect occurs between the exposed surface of the cathode conductor layer and the cathode metal layer, so that mechanical adhesion between the two Will be very good Thus immersion into the molten solder bath, even if thermal stress is applied due to repeated loading and unloading of the far-infrared furnace, in which no longer that the cathode metal layer is peeled off from the cathode conductor layer.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a chip-shaped tantalum solid electrolytic capacitor according to an embodiment of the present invention, and FIG.
Shows the state where the cathode conductor layer is formed on the capacitor element. In FIGS. 1 and 2, reference numeral 11 denotes a porous anode body formed by molding and sintering tantalum metal powder which is a valve metal, and a dielectric oxide film is formed on the surface of the anode body 11 by anodic oxidation. An electrolyte layer of manganese dioxide is formed on the surface of this dielectric oxide film. The anode lead wire 12 is made of tantalum wire and is led out from the anode body 11. A series of processing steps on the surface of the anode body 11 is performed with the anode lead wire 12 connected to the metal ribbon 13.

Reference numeral 14 denotes a Teflon plate attached to the anode lead-out wire 12. This Teflon plate 14 prevents manganese nitrate from crawling up and adhering manganese dioxide to the anode lead-out wire 12 when the electrolyte layer is formed on the anode body 11. It is an insulating plate to prevent. Further, a cathode layer 15 is sequentially formed on the electrolyte layer of the anode body 11 by a dipping method to form a capacitor element 11a.
Are configured. Reference numeral 16 denotes a cathode conductor layer. The cathode conductor layer 16 is formed on the opposing surface 17 of the cathode layer 15 provided around the capacitor element 11a on the side opposite to the anode lead wire 12, and on the opposing surface 17. Adjacent adjacent cathode layer 1
5, the cathode conductor layer 16 is formed by immersing the capacitor element 11a in a viscous liquid of a conductive resin containing particles of metal or inorganic material 18 or by using a dispenser. Is forming. Reference numeral 19 denotes an exterior resin layer. The exterior resin layer 19 sets the capacitor element 11a in a mold so that the anode lead wire 12 is pulled out to one side, and the tip portion of the anode lead wire 12 in FIG. Cathode conductor layer 16 and cathode layer 15 except for a part of layer 16
Further, it is formed by transfer molding or injection molding using epoxy resin so that the entire capacitor element 11a is covered with resin.

FIGS. 4 (a), (b), (c), (d), and (e) show the manufacturing process of the chip-shaped tantalum solid electrolytic capacitor in one embodiment of the present invention. Reference numeral 12a denotes an anode lead surface of the exterior resin layer 19, and since the cathode conductor layer 16 formed on the facing surface 17 located on the opposite side of the anode lead wire 12 is longer than the external dimensions of the product, the exterior resin layer 19 is formed. The molded product of is longer than the external dimensions of the product.

FIG. 4B shows a state in which the molded body of the exterior resin layer 19 in FIG. 4A is cut or ground to the external dimensions of the product. In FIG. 4B, reference numeral 16a denotes a cathode lead-out surface, and this cathode lead-out surface 16a is exposed as shown in FIG. 1 by cutting the exterior resin layer 19 and the cathode conductor layer 16. The cathode conductor layer 16 is exposed on the cathode lead-out surface 16a. After that, exposed portions of the metal particles 18 such as silver, copper, nickel, iron, lead, tin and aluminum contained in the cathode conductor layer 16 are etched and dissolved with a solution of nitric acid, hydrochloric acid, sulfuric acid or the like. Together with the cathode conductor layer 1
As shown in FIG. 3, the ceramic particles such as silica particles contained in No. 6 and the inorganic material particles 18 are dissolved by etching with a hydrogen fluoride solution.
Since the melted portion of 1 is concave, the unevenness 16b is formed on the exposed surface of the cathode conductor layer 16.

FIG. 4 (c) shows a state in which the anode lead wire 12 is separated from the metal ribbon 13.

FIG. 4D shows a state in which the anode metal layer 20 and the cathode metal layer 21 are formed. This metal layer is shown in FIG.
As shown in FIG. 3, the anode lead wire 12, the anode lead surface 12a, and the anode metal layer 20 formed on the surface of a part of the molded body of the exterior resin layer 19, the cathode lead surface 16a, and the exterior resin layer 1 are formed.
The cathode metal layer 21 formed on a part of the surface of the molded body of No. 9 and the metal layers 20 and 21 of both electrodes are electroless plating, electrolytic plating, wet forming method, vapor deposition, and ion sputtering dry forming method. And a conductive resin layer may be included in this case.

FIG. 4 (e) shows a state in which the anode metal layer 20 and the cathode metal layer 21 are covered with a solder metal layer.
Reference numeral 22 is a solder metal layer on the anode side, and 23 is a solder metal layer on the cathode side. These solder metal layers 22 and 23 are formed by solder coating with molten solder or electrolytic solder plating.

Table 1 shows that the conventional chip-shaped solid electrolytic capacitor and the chip-shaped solid electrolytic capacitor according to one embodiment of the present invention are immersed in a molten solder bath at 260 ° C. for 5 seconds each, 5 times or 10 times. It shows the test results comparing the peeling failure rate of the cathode metal layer when repeated twice.

[0017]

[Table 1]

As is clear from this (Table 1), the conventional chip-shaped solid electrolytic capacitor had a defective peeling of the cathode metal layer. However, in the chip-shaped solid electrolytic capacitor of one embodiment of the present invention, No peeling failure of the cathode metal layer occurred.

In the above-described embodiment of the present invention, the anode lead wire 1 in the cathode layer 15 of the capacitor element 11a.
2, a cathode conductor layer 16 containing particles 18 of a metal or an inorganic material is formed on a portion located on the side opposite to 2, and then the outer surfaces of the capacitor element 11a and the cathode layer 15 are connected to the tip of the anode lead wire 12 and the cathode. Except for a part of the conductor layer 16, the exterior resin layer 19 is coated, and the exposed portion of the metal or inorganic particles 18 contained in the cathode conductor layer 16 and exposed is nitric acid, hydrochloric acid, sulfuric acid, or the like. Since the unevenness 16b is formed on the exposed surface of the cathode conductor layer 16 by etching and dissolving with the solution of No. 1 and hydrogen fluoride solution, the exterior resin layer 1
9 can increase the surface roughness of the exposed surface of the cathode conductor layer 16, and as a result, by forming the cathode metal layer 21 on the exposed surface of the cathode conductor layer 16 as described above, An anchor effect is generated between the exposed surface of the conductor layer 16 and the cathode metal layer 21, so that the mechanical adhesion between the two becomes very excellent, which results in immersion in a molten solder bath and far infrared rays. The cathode metal layer 21 does not peel off from the cathode conductor layer 16 even if thermal stress is applied by repeated loading and unloading in the furnace.

[0020]

As described above, according to the method for manufacturing a chip solid electrolytic capacitor of the present invention, a metal is provided in a portion of the capacitor element on the side opposite to the anode lead wire in the cathode layer,
A cathode conductor layer containing inorganic particles is formed, and then the outer surfaces of the capacitor element and the cathode layer are covered with an exterior resin layer excluding the tip of the anode lead wire and a part of the cathode conductor layer. Further contained in the cathode conductor layer, and exposed metal, because the exposed portion of the particles of the inorganic substance is dissolved by etching to form irregularities on the exposed surface of the cathode conductor layer, so that the surface from the exterior resin layer It is possible to increase the surface roughness of the exposed surface of the cathode conductor layer, and as a result, by forming a cathode metal layer on the exposed surface of such a cathode conductor layer, the exposed surface of the cathode conductor layer. Since an anchor effect occurs between the cathode metal layer and the cathode metal layer, the mechanical adhesion between the two becomes extremely excellent, which results in thermal stress due to repeated immersion in the molten solder bath and removal from and in the far infrared furnace. Even if the cathode is added Genus layers are made rather than that separated from the cathode conductor layer.

[Brief description of drawings]

FIG. 1 is a sectional view of a chip-shaped tantalum solid electrolytic capacitor showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a state in which a cathode conductor layer is formed on a capacitor element in the solid electrolytic capacitor.

FIG. 3 is a cross-sectional view showing a state in which exposed portions of metal and inorganic particles contained in a cathode conductor layer of the solid electrolytic capacitor are dissolved by etching.

4A to 4E are perspective views showing manufacturing steps of the solid electrolytic capacitor.

FIG. 5 is a sectional view of a conventional chip-shaped tantalum solid electrolytic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Anode body 11a Capacitor element 12 Anode lead wire 12a Anode lead surface 15 Cathode layer 16 Cathode conductor layer 16a Cathode lead surface 16b Concavo-convex 18 Metal or inorganic particle 19 Exterior resin layer 20 Anode metal layer 21 Cathode metal layer

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

Claims (1)

[Claims] 1. A capacitor element is constructed by providing a dielectric oxide film, an electrolyte layer, and a cathode layer on an anode body made of a valve metal in which an anode lead wire is embedded so that one end of the anode lead wire is exposed. A metal, a cathode conductor layer containing particles of an inorganic material is formed on a portion of the capacitor element located on the side opposite to the anode lead-out line in the cathode layer, and thereafter, the capacitor element, the cathode conductor layer, and the cathode layer. The outer surface is covered with an outer resin layer excluding the tip of the anode lead wire and a part of the cathode conductor layer, and is further contained in the cathode conductor layer, and the exposed metal and inorganic particles are exposed. A part is dissolved by etching to form irregularities on the exposed surface of the cathode conductor layer, and then an anode metal layer connected to the anode lead wire is formed on the anode lead wire exposed side of the exterior resin layer, and the exterior resin Layer cathodic conductor layer exposure The cathode layer and chip solid electrolytic method for producing a capacitor to form a cathode metal layer to be connected to the cathode conductor layer.