JPH0684712A - Manufacture of chip type solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To prevent the characteristic deterioration of a capacitor element while it is by reducing the intrusion of a mechanical and thermal stresses and moisture into the element. CONSTITUTION:After forming an interior resin layer 12 on the surface of a conductor layer 7 constituting a capacitor element 8 by dipping the layer 7 in a resin while a cathode lead wire 9 is connected to the layer 7 with a conductive bonding agent 10 so that the wire 9 can be led out in the same direction as that of an anode lead wire 3, the led-out part of the wire 9 is bent along the layer 12 and an external cathode and anode terminals 13 and 14 are respectively welded to the wires 9 and 3 so that the terminals 13 and 14 can be led out in opposite directions. Then a coating resin layer 15 is formed by transfer molding.

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.

[0002]

2. Description of the Related Art A conventional chip type solid electrolytic capacitor has an oxide film, a solid electrolyte layer, a carbon layer, on the surface of an anode body made of a valve metal having an anode lead wire 21 as shown in FIG. The conductor layers are sequentially formed to form the capacitor element 22, and then the capacitor element 22 is formed.
The cathode external terminal 24 is connected to the conductor layer constituting the anode via the conductive adhesive 23 so as to be drawn out in the direction opposite to the anode lead wire 21, and the anode external terminal 25 is connected to the anode lead wire 21. Next, the capacitor element 22 including the connection portion of the anode external terminal 25 and the cathode external terminal 24
After covering the whole of the anode lead wire 21 with the exterior resin 26, the exposed portions of the anode external terminal 25 and the cathode external terminal 24 are bent along the side and bottom surfaces of the exterior resin 26.

However, in the chip type solid electrolytic capacitor having the above-mentioned structure, the exterior is made of one layer of the exterior resin 26, and the exterior resin 26 is formed directly on the capacitor element 22, so that it can be applied to a printed circuit board or the like. If a rapid temperature change occurs during mounting or during the manufacturing process, the exterior resin 26
In addition to the drawback that the capacitor element 22 is damaged by the thermal stress of the capacitor and leakage current increases, a small amount of water easily enters the capacitor element 22 under high temperature and high humidity, and an oxide film and a conductor serving as a cathode layer are formed. In addition to the increase in tan δ, ESR, impedance, and decrease in capacitance due to poor contact with the layers, corrosion of the anode body caused large leakage current and short circuit.

Further, since the conductor layer serving as the cathode layer is directly connected to the cathode external terminal 24 with the conductive adhesive 23,
Due to deterioration of the conductive adhesive 23 due to moisture or heat, tan
This also caused further increases in δ, ESR, impedance, and eventually the occurrence of open defects.

Therefore, the capacitor element 22 is connected to the cathode external terminal 24, and the anode lead wire 21 is connected to the anode external terminal 2.
Although it is conceivable to provide the interior resin layer in a state of being connected to No. 5, it is not possible to dip coat the capacitor element 22 portion in such a state, and as the interior resin layer forming means, brush coating is applied one by one. And the like, there is a problem that the workability is poor and it is not suitable as an industrial production means, and at the same time, the interior resin layer formation state is insufficient for the connection part with the cathode external terminal, The leakage current increase due to thermal stress and the deterioration of various characteristics due to the infiltration of water have not been sufficiently prevented, and there has been a practical situation to be solved.

[0006]

As described above, in the conventional chip type solid electrolytic capacitor, leakage current increases due to thermal stress, capacitance decreases due to moisture or heat, ta
It has a cause of increase of nδ, ESR, impedance, short circuit failure and open circuit failure. Even if a measure against characteristic deterioration is taken, its effect is insufficient and workability is also improved. It deteriorated significantly and was not practical.

The present invention has been proposed in order to solve the problems of the prior art as described above, and its purpose is to exert an influence on the capacitor element due to thermal stress and moisture, and further, to a cathode external terminal connecting portion. It is an object of the present invention to provide a method for manufacturing a chip-type solid electrolytic capacitor, which has good workability without causing deterioration of electrical characteristics and defects due to deterioration of the.

[0008]

A method of manufacturing a solid electrolytic capacitor according to the present invention comprises an oxide film layer, a solid electrolyte layer, and a solid electrolyte layer on a surface of an anode body made of a valve metal having an anode lead wire.
A step of sequentially forming a carbon layer and a conductor layer to obtain a capacitor element, and a step of connecting a cathode lead wire to the conductor layer so as to be led out in the same direction as the anode lead wire,
Forming an interior resin layer by resin-coating the entire capacitor element except the connection portion of the anode lead wire and at least the external terminal of the cathode lead wire; and folding the cathode lead wire in a direction opposite to the anode lead wire. And a step of connecting the anode lead wire to the anode external terminal, and thereafter, a step of forming an exterior resin layer.

[0009]

When the solid electrolytic capacitor is manufactured by the manufacturing method of the present invention having the above-described structure, the entire capacitor element including the conductor layer constituting the capacitor element and the connecting portion of the cathode lead wire with the conductive adhesive is Since the inner resin layer is completely covered and the entire inner resin layer is covered with the outer resin layer, thermal stress and mechanical stress applied to the outer resin, and further, the capacitor element and the conductivity of moisture The influence of the conductive adhesive between the body layer and the cathode lead wire on the connection portion is greatly alleviated, and the deterioration of various electrical characteristics can be largely prevented. Further, the cathode lead wire and the cathode external terminal can be connected by welding, and the cause of the deterioration of the electrical characteristics caused by this portion can be eliminated and at the same time the interior resin layer can be easily formed. The method of the present invention has good workability.

[0010]

EXAMPLES An example of a method for manufacturing a solid electrolytic capacitor according to the present invention will be specifically described below with reference to FIGS. 1 and 2.

First, as shown in FIG. 2, the surface of the anode is electrochemically etched, and the anode lead wire is formed on the anode foil 2 made of a 3 mm square aluminum foil on which the dielectric oxide film 1 is formed through a chemical conversion process. 3 is attached, and then this anode foil 2 is immersed in a 2 mol / liter / pyrrole / ethanol solution for 5 minutes, and further immersed in a 0.5 mol / liter ammonium persulfate aqueous solution for 5 minutes to form polypyrrole by chemical oxidative polymerization. A chemically polymerized film 4 is formed, and further pyrrole monomer 0.2 mol / liter and sodium alkylnaphthalene sulfonate as a supporting electrolyte 0.0
It is immersed in an aqueous solution containing 5 mol / liter, and the chemically polymerized film 4 made of polypyrrole is used as an anode, and constant current electrolytic oxidative polymerization (1 mA / cm ² , 1 h) is performed with an external electrode, and polypyrrole is formed by electrolytic oxidative polymerization. After forming the electrolytically polymerized film 5 consisting of, the carbon layer 6 is formed by immersing it in colloidal carbon, and then a silver paste is applied on the carbon layer 6 to form the conductor layer 7 and the capacitor element 8
Make up.

Next, the conductor layer 7 of the capacitor element 8 is formed.
After connecting the cathode lead wire 9 through the conductive adhesive 10 so as to lead out in the same direction as the anode lead wire 3, the whole capacitor element 8 including the connecting portion between the cathode lead wire 9 and the conductor layer 7 Is dipped, pulled up and dried in, for example, a resin dip tank 11 made of a liquid epoxy resin. At this time, the resin dip tank 1 is provided so that the resin is not applied to the connection portions of the anode lead wire 3 and the cathode lead wire 9 with the external terminals.
The immersion position in 1 is up to AA '.

After forming the interior resin layer 12 by obtaining the above means as shown in FIG. 1, the cathode lead wire 9 is placed along the surface of the interior resin layer 12 and the anode lead wire 3 is formed.
And the cathode external terminal 13 is connected to the tip of the cathode lead wire 9 and the anode external terminal 14 is connected to the tip of the anode lead wire 3 in the opposite direction. The external resin layer 15 is applied by transfer molding to form a capacitor body, and the anode external terminal 14 and the cathode external terminal 13 led out from the side surface of the capacitor body are extended along the side surface of the capacitor body to the bottom surface of the capacitor body. Then, the chip type solid electrolytic capacitor having a rated voltage of 16 V and a nominal electrostatic capacity of 1 μF was completed.

On the other hand, as Comparative Example 1 according to the prior art, the same as the above-mentioned present invention except that the conductor layer constituting the capacitor element and the cathode external terminal are connected by a conductive adhesive and the interior resin layer is not provided. As a comparative example 2, a chip-type solid electrolytic capacitor having a rated voltage of 16 V and a nominal electrostatic capacity of 1 μF, which was produced by the method shown in FIG. 3, was used as a conductive layer for a capacitor element and a cathode external terminal. , And after that, a chip type solid electrolytic capacitor having a rated voltage of 16 V and a nominal electrostatic capacity of 1 μF, which is manufactured by the same method as that of the present invention described above, is completed except that an epoxy resin is brushed and an inner resin layer is applied. did.

The solid electrolytic capacitor (Example A) in the embodiment of the present invention completed as described above, the solid electrolytic capacitor (Conventional example B) as Comparative Example 1 according to the prior art, and the solid electrolytic capacitor as Comparative Example 2 A large number of samples were prepared for (conventional example C) and their initial characteristics and various characteristics after a high temperature / high humidity test (85 ° C., 90% RH, 100 h) were examined, and shown in Tables 1 and 2. The result is as follows.

ESR in Tables 1 and 2 is frequency 100K
It is a numerical value in Hz, the number of samples is 100 each, the numerical value is an average value, and the numerical value in parentheses shows variation.

[0017]

[Table 1]

[0018]

[Table 2]

As is clear from Tables 1 and 2 above, in the initial characteristics, there is no difference in capacitance and tan δ between Example A, Conventional Example B and Conventional Example C, but leakage current and ESR are the same as those of the conventional example. The example A is superior to the example B and the conventional example C, and this is due to the difference in the thermal influence on the capacitor element during the manufacturing process.

After the high-temperature and high-humidity test, Example A shows stable characteristics in all characteristics, whereas the characteristics of Conventional Example B and Conventional Example C are greatly deteriorated. The tan δ of B, the deterioration of leakage current and ESR characteristics, and the deterioration of ESR characteristics of the conventional example C show severe results. Due to the deterioration of the electric conductivity of the molecule, in the chip type solid electrolytic capacitor using the conductive polymer film as the solid electrolyte, the conductive adhesive used to connect the conductive layer that constitutes the capacitor element and the cathode lead wire. The entire capacitor element including the agent is completely made into internal resin, welding is possible as the connection of the external terminal of the cathode, and the external resin is made into a two-layer resin. Advantages of the production unit according to the invention which enables to easily have been demonstrated.

The present invention is not limited to the above-mentioned embodiment. For example, as the anode foil, a valve action metal foil such as tantalum or niobium other than aluminum foil, or
Needless to say, the present invention can be applied to a sintered element formed by sintering a metal powder of aluminum, tantalum, niobium or the like. Further, it is also applicable to those using solid electrolytes such as polythiophene, polyfuran or polyaniline, TCNQ complex, manganese dioxide, etc. other than polypyrrole as the conductive polymer, and further silicone resin, Teflon resin other than epoxy resin as the interior resin layer. May be used.

[0022]

As described above, according to the present invention, it is possible to obtain a method of manufacturing a chip type solid electrolytic capacitor which has good workability and is free from deterioration of various characteristics under high temperature and high humidity and which has high practical value. .

[Brief description of drawings]

FIG. 1 is a front sectional view showing a chip-type solid electrolytic capacitor obtained according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of forming an internal resin layer on a capacitor element according to an embodiment of the present invention.

FIG. 3 is a front sectional view showing a chip-type solid electrolytic capacitor obtained by a conventional example.

[Explanation of symbols]

 1 Oxide film 2 Anode foil 3 Anode lead wire 4 Chemically polymerized film 5 Electrolytic polymerized film 6 Carbon layer 7 Conductor layer 8 Capacitor element 9 Cathode lead wire 10 Conductive adhesive 12 Interior resin layer 13 Cathode external terminal 14 Anode external terminal 15 Exterior resin layer

Claims (1)

[Claims] 1. A step of obtaining a capacitor element by sequentially forming an oxide film layer, a solid electrolyte layer, a carbon layer and a conductor layer on the surface of the anode body made of a valve action metal from which the anode lead wire is derived, and the conductor layer. A step of connecting the cathode lead wire so as to be led out in the same direction as the anode lead wire, and a resin coating for the entire capacitor element excluding the connection portion of the anode lead wire and at least the external terminal of the cathode lead wire, A step of forming a layer, a step of folding back the cathode lead wire in a direction opposite to the anode lead wire, and connecting a tip end portion to a cathode external terminal and the anode lead wire to an anode external terminal, and thereafter forming an exterior resin layer. A method of manufacturing a chip-type solid electrolytic capacitor, which comprises sequentially performing the steps of: