JP2850823B2 - Manufacturing method of chip type solid electrolytic capacitor - Google Patents

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 chip type solid electrolytic capacitor, and more particularly to a method for forming external positive and negative terminals.

[0002]

2. Description of the Related Art Conventional chip-type solid electrolytic capacitors are:
As shown in FIG. 3, an external cathode terminal 13 is connected to a capacitor element 11 having a dielectric film layer, a solid electrolyte layer and a cathode metal layer formed thereon with a conductive adhesive 15 made of silver paste. After connecting the anode lead 12 thus derived to the external anode terminal 14 by resistance welding, a part of the element 11 and the external positive and negative terminals 14 and 13 is molded with an epoxy-based exterior resin material 16 to form a molding resin material. The external positive and negative terminals 14, 13 derived from 1 were bent and formed.

[0003]

In the above-mentioned conventional method for manufacturing a chip-type solid electrolytic capacitor, since the capacitor element 11 is packaged with a resin material 16 such as an epoxy resin, stress from all directions from the resin material 16 is reduced. As a result, there is a problem that the leakage current of the capacitor increases. Also, the thickness of the product is increased by the thickness of the resin, which hinders a reduction in thickness. Furthermore, since the external cathode terminal 13 is connected with the conductive adhesive 15 made of expensive silver paste, the cost increases and there is a problem in connection reliability.

[0004]

According to the present invention, there is provided a method for manufacturing a chip-type solid electrolytic capacitor, comprising: an external anode lead frame which can be soldered to an anode lead made of a valve metal implanted on an anode body made of a valve metal. Connecting, forming an insulating member by molding on an anode lead-out surface including the external anode lead frame connecting portion, and sequentially forming a dielectric film, a solid electrolyte layer, and a cathode metal layer on the peripheral surface of the anode body And cutting the external anode lead frame and then bending and molding it along the insulating member.

[0005] The present invention provides a method for forming a dielectric film, a solid electrolyte layer, and a cathode metal layer on an anode body, and forming an anode lead-out surface on the entire peripheral surface of the capacitor element without forming an exterior resin serving as an insulating portion. Since the insulating member is formed only by molding, the capacitor element is not subjected to stress from the exterior resin, so that deterioration of the leakage current can be prevented. Further, since the cathode metal layer of the capacitor element plays a role of an external cathode unit, it is not necessary to attach an external cathode lead with expensive silver paste, and the connection reliability is improved. Furthermore, there is an advantage that the thickness can be reduced by the amount corresponding to the external cathode lead and the exterior resin as compared with the conventional one.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to a chip type tantalum solid electrolytic capacitor as an example. FIG.
FIG. 1 is a cross-sectional view of a chip-type tantalum solid electrolytic capacitor obtained by a manufacturing method of the present invention. In the drawing, 1 is an anode body made of a sintered body of tantalum metal particles, 1 is an anode lead made of tantalum metal wire, 3 is an external anode lead frame plated with solder, 4 is an insulating member made of epoxy resin, 5 is 5 A dielectric film consisting of a tantalum oxide film,
6 is a solid electrolyte layer made of polypyrrole, 7 is a conductive metal layer made of a graphite layer and a silver paste, 8 is a nickel plating layer, 9 is solder, and 10 is a cathode metal layer constituting an external cathode terminal.

Hereinafter, a method of manufacturing the above-mentioned chip type solid electrolytic capacitor will be described. An anode lead 2 made of a tantalum metal wire is planted on an anode body 1 obtained by press-molding a tantalum powder having a particle size of 1 micron order. Next, 15
An external anode lead frame formed by sintering in a vacuum furnace set to a temperature of 00 ° C. or more and then forming a solder plating having a thickness of about 5 μm on a lead frame made of an alloy of iron and nickel as shown in FIG. An anode lead 2 made of a tantalum metal wire is connected to 3 by resistance welding. Next, the anode lead 2 including the welding point between the external anode lead frame 3 and the anode lead 2 is formed of epoxy resin on the surface of the anode body 2 leading out including the welding point, with the anode lead 2 fixed to the external anode lead frame 3. An insulating member 4 is formed. The thickness of the insulating member 4 is substantially the same as the thickness of the anode body 1,
It is desirable that the insulating member 4 and the insulating member 4 be substantially on the same plane.

Next, the anode body 1 fixed to the external anode lead frame 3 is immersed in a 0.1 vol% phosphoric acid aqueous solution,
Perform anodic oxidation at a rate of 1 V / min.
A dielectric film layer 5 made of a tantalum pentoxide film of 2,000 Å is formed. Next, the anode body 1 is immersed in a 20 vol% methanol solution of copper dodecylbenzenesulfonate, impregnated inside the anode body 1, and then methanol is evaporated in an oven at a temperature of 50 ° C. Next, it is immersed in a 10% pyrrole monomer solution to form a polypyrrole layer 6 to be a solid electrolyte layer. The immersion of the copper dodecylbenzenesulfonate and the pyrrole monomer is repeated 10 to 20 times until a polypyrrole layer 6 of about 0.1 to 0.5 μm is formed inside the anode body 1 and 5 to 20 μm outside the anode body 1. Done. Next, a conductive metal layer 7 composed of a graphite layer and a silver paste layer is formed on the polypyrrole layer 6 by a known method, and then immersed in an electroless nickel plating bath for 30 minutes to form a nickel plating layer 8 having a thickness of about 5 microns. Temperature 2
The anode body 1 is dipped in a eutectic solder bath at 20 ° C. to form a solder layer 9 on the nickel plating layer 8. Thus, the graphite layer, the nickel plating layer, and the solder layer 3
A cathode metal layer 10 composed of a layer is formed. Next, the external anode lead frame 3 derived from the insulating member 4 was cut, and then bent along the insulating member 4 into an L-shape to produce a chip-type solid electrolytic capacitor.

The rated voltage of 16 V produced by the above method,
A voltage of 16 V is applied to 100 chip-shaped tantalum solid electrolytic capacitors having a capacitance of 10 μF, and the leakage current failure results after 1 minute are shown in Table 1. However, the leakage current is 1 μA
The ones exceeding the above were regarded as defective. For comparison, the leakage current was measured for a capacitor manufactured by the conventional technique. It can be seen that the capacitor maintained according to the present invention has clearly reduced leakage current defects as compared with the conventional product.

[0010]

[Table 1]

The reason why the nickel plating layer is formed on the silver paste layer is to prevent the so-called silver erosion phenomenon in which the silver paste is diffused into the solder. In the manufacturing method of the present invention, since the cathode metal layer of the capacitor element is used as it is as the external anode terminal, it is necessary to use a nickel plating layer to increase the heat resistance of the cathode metal layer. Also, since the silver paste layer is used as a catalyst for forming the electroless nickel plating layer, the copper paste may be a palladium paste or a mixture thereof. further,
In addition to nickel plating, plating of copper, gold, or the like may be used.

As another embodiment of the present invention, the solid electrolyte 6
Instead of polypyrrole, polyaniline, which is a kind of conductive polymer material, was formed. Polyaniline is formed by immersing anode body 1 in an aqueous solution obtained by diluting a solution obtained by mixing para-toluenesulfonic acid and aniline monomer in the same molar amount to 40% with water, and then immersing in an aqueous solution of 5% ammonium bichromate. The polyaniline film was formed by oxidative polymerization. When polyaniline is used for the solid electrolyte layer 6, there is an advantage that heat resistance and material cost can be reduced as compared with polypyrrole. If polypyrrole or polythiofin is used for the solid electrolyte layer 6, the solid electrolyte layer 6 can be formed at room temperature as compared with conventional manganese dioxide generated by thermal decomposition of manganese nitrate. There is an advantage that the applied external anode lead frame 3 can be connected. Therefore, there is an advantage that the process can be simplified as compared with the conventional method of manufacturing a capacitor using manganese dioxide and solid electrolyte 6.

In the embodiment of the present invention, a chip type tantalum solid electrolytic capacitor has been described as an example, but it is a matter of course that the present invention can be applied to a chip type aluminum solid electrolytic capacitor and the like.

[0014]

As described above, according to the present invention, after an external anode lead frame is connected to an anode lead, an insulating member is provided by molding only on the lead-out surface of the anode lead, and a dielectric material is sequentially provided on the peripheral surface of the anode body. The following effects are obtained by forming the coating layer, the solid electrolyte layer, and the cathode metal layer. Since the chip type capacitor can be obtained without covering the capacitor element with the resin, the stress received from the resin is eliminated and the deterioration of the leakage current can be prevented. The thickness can be reduced by the thickness of the exterior resin. Since the external cathode terminal and the expensive conductive adhesive for attaching the external cathode terminal are not required, the cost can be reduced and the connection reliability can be improved. Since the manufacturing process can be simplified, the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a chip type solid electrolytic capacitor manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the capacitor element during the manufacturing method is fixed to an external anode lead frame.

FIG. 3 is a longitudinal sectional view of a chip-type solid electrolytic capacitor manufactured by a conventional manufacturing method.

[Explanation of symbols]

 Reference Signs List 1 anode body 2 anode lead 3 external anode lead frame 4 insulating member 5 dielectric coating layer 6 solid electrolyte layer (polypyrrole) 7 conductive metal layer (graphite, silver paste) 8 plating layer (nickel plating layer) 9 solder layer 10 cathode metal Layer (external cathode terminal)

Claims (3)

(57) [Claims] 1. A step of connecting a solderable external anode lead frame to an anode lead made of a valve metal implanted on an anode body made of a valve metal, and deriving an anode lead including the external anode lead frame connection portion. Forming an insulating member by molding on the surface; forming a dielectric film layer, a solid electrolyte layer, and a cathode metal layer on the peripheral surface of the anode body in order; And forming the chip-type solid electrolytic capacitor. 2. The method according to claim 1, wherein said solid electrolyte layer is made of any one of polypyrrole, polythiophene, and polyaniline. 3. The cathode metal layer according to claim 1, wherein said cathode metal layer comprises a laminate of a conductive metal layer, a plating layer, and a solder layer.
3. The method for manufacturing a chip-type solid electrolytic capacitor according to any one of claims 1 to 2.