JPH07114176B2 - Method for manufacturing 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 solid electrolytic capacitor, and more particularly to a method for connecting a cathode layer and a cathode terminal.

[0002]

2. Description of the Related Art Conventionally, a solid electrolytic capacitor is connected to a cathode layer and a cathode terminal by melting solder or the like. For example, Japanese Utility Model Publication No. 62-2762, JP-A-2-
In Japanese Patent No. 46715, in order to connect the cathode layer and the cathode terminal via a fuse made of solder, the fuse is heated to a melting temperature or higher by a parallel gap method or a pulse heating method to be fused and brazed.

Further, in JP-A-63-289950, an oxygen-free copper lead frame is brazed to a metal layer of a substrate by using a brazing material.

[0004]

Since the above-described conventional method for manufacturing a solid electrolytic capacitor for connecting a cathode layer and a cathode terminal is all brazing using a brazing material such as solder,
When the brazing portion rises above the melting temperature of the brazing material, the brazing material melts and flows out, causing a short circuit defect or an open defect.

An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor which connects a cathode layer and a cathode terminal without causing a short circuit defect or an open defect by thermocompression bonding without using a brazing material.

[0006]

A method of manufacturing a solid electrolytic capacitor according to the present invention comprises a step of forming tantalum powder and heating and firing the same to form a capacitor element in which an anode lead is erected, and an anode terminal on the anode lead. And a step of forming a cathode layer on the peripheral surface of the capacitor element via an oxide layer and a semiconductor layer, and a cathode terminal is placed on the cathode layer via a metal layer and heated to perform solid phase diffusion. A step of connecting by bonding, a step of covering the entire peripheral surface of the capacitor element to which the anode terminal and the cathode terminal are connected with a mold resin, the cathode terminal is oxygen-free copper, while, The metal layer is one of gold and copper.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.

1A and 1B are a sectional view of a solid electrolytic capacitor according to a first embodiment of the present invention and a partially enlarged sectional view of its cathode terminal portion. The first embodiment is shown in FIG.
As shown in (a) and (b), first, tantalum powder is molded and heated to form the capacitor element 3. In this capacitor element 3, a tantalum wire is previously set up as an anode lead 1, and an anode terminal 2 is welded to this anode lead 1.

On the other hand, the cathode terminal 5 is formed on the peripheral surface of the capacitor element 3 with an oxide layer and a semiconductor layer (both not shown) made of silver paste or the like on the cathode layer 6 and a metal layer 7 such as gold or copper. It is placed through, heated and connected by solid phase diffusion bonding. The cathode terminal 5 is formed of oxygen-free copper, and the entire surface is solder-plated. Next, the entire peripheral surface of the capacitor element 3 to which the anode terminal 2 and the cathode terminal 5 are connected in this manner is covered with the mold resin 4 such as epoxy resin to obtain the solid electrolytic capacitor according to the first embodiment.

Next, a method of connecting the cathode terminal 5 to the cathode layer 6 will be described. FIG. 2 is a perspective view illustrating a method of connecting a cathode terminal to the cathode layer according to the first embodiment of the present invention. As shown in FIG. 2, first, the metal layer 7 on which the connection portion of the cathode terminal 5 made of oxygen-free copper is placed on the cathode layer 6 via the metal layer 7 such as gold or copper is gold-plated or copper-plated. And the like. Next, the heater chip 8 made of molybdenum or the like is brought into contact with the upper surface of the connecting portion of the cathode terminal 5, and an electric current is applied to the heater chip 8 to generate heat. Next, the heater chip 8 heats and pressurizes the cathode terminal 5. At this time, when the temperature of the connecting portion rises up to 300 ° C. which is the softening temperature of the oxygen-free copper that is the base material of the cathode terminal 5, the copper of the cathode terminal 5 and the metal of the metal layer 7 or copper or the like interdiffuse and solid-phase. The cathode terminal 5 is connected to the cathode layer 6 by diffusion bonding.

FIG. 3 is a sectional view of a solid electrolytic capacitor according to a second embodiment of the present invention. In the second embodiment, as shown in FIG. 3, similarly to the first embodiment, first, tantalum powder is thermoformed to form the capacitor element 3. A tantalum wire is previously attached to the capacitor element 3 by an anode lead 1
Then, the anode terminal 2 is welded to the anode lead 1.

On the other hand, the cathode terminal 5 is formed on the peripheral surface of the capacitor element through an oxide layer, a semiconductor layer (both not shown) and a cathode layer 6 formed of silver paste or the like, and a metal layer 7 such as gold or copper is interposed. Place and heat to connect by solid phase diffusion bonding. The cathode terminal 5 is formed of oxygen-free copper, and the entire surface is solder-plated. The method of connecting the cathode terminal 5 to the cathode layer 6 is the same as that of the first embodiment described based on FIG. Next, the connecting portion between the cathode layer 6 and the cathode terminal 5 is covered with the reinforcing resin 9.

Next, in this way, the anode terminal 2 and the cathode terminal 5 are
And the connection between the cathode layer 6 and the cathode terminal 2 is covered with the reinforcing resin 9 and the entire circumference of the capacitor element 3 is covered with the mold resin 4 such as epoxy resin. A capacitor is obtained. As described above, in the second embodiment, the connection is reinforced by the reinforcing resin 9, so that it is stronger than the solid electrolytic capacitor manufactured according to the first embodiment.

FIG. 4 is a characteristic diagram showing the temperature dissimilarity of the connection strength between the present invention and the conventional example. As shown in FIG. 4, since the connection of the present invention is solid phase diffusion bonding, it has stable strength even at a high temperature, unlike the conventional connection using a brazing material such as solder.

[0015]

As described above, according to the present invention, the oxygen-free copper is momentarily heated by the heater chip and the cathode layer and the cathode terminal are pressure-welded by the solid phase diffusion bonding, so that the stability is maintained in a short time. There is an effect that excellent terminal connection can be obtained.

Further, since stable bonding strength can be obtained even at high temperature, there is an effect that a stable connection can be maintained even against heat when mounting components.

[Brief description of drawings]

1A and 1B are a sectional view of a solid electrolytic capacitor according to a first embodiment of the present invention and a partially enlarged sectional view of a cathode terminal portion thereof.

FIG. 2 is a perspective view illustrating a method of connecting a cathode terminal to the cathode layer according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a solid electrolytic capacitor according to a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing temperature differences in connection strength between the present invention and a conventional example.

[Explanation of symbols]

 1 Anode Lead 2 Anode Terminal 3 Capacitor Element 4 Mold Resin 5 Cathode Terminal 6 Cathode Layer 7 Metal Layer 8 Heater Chip 9 Reinforcing Resin

Claims (4)

[Claims] 1. A step of molding a tantalum powder and heating it to form a capacitor element in which anode leads are erected,
Welding an anode terminal to the anode lead, forming a cathode layer on the peripheral surface of the capacitor element via an oxide layer and a semiconductor layer, and placing a cathode terminal on the cathode layer via a metal layer. A solid electrolytic capacitor comprising a step of heating and connecting by solid-phase diffusion bonding, and a step of coating the entire peripheral surface of the capacitor element to which the anode terminal and the cathode terminal are connected with a mold resin. Manufacturing method. 2. A step of forming a capacitor element in which anode leads are planted by molding tantalum powder and heating and firing the same.
Welding an anode terminal to the anode lead, forming a cathode layer on the peripheral surface of the condenser element via an oxide layer and a semiconductor layer, and placing a cathode terminal on the cathode layer via a metal layer. A step of heating and connecting by solid phase diffusion bonding, a step of coating a connecting portion of the cathode layer and the cathode terminal with a reinforcing resin, and a mold resin covering the entire circumference of the capacitor element coated with the reinforcing resin. The method for producing a solid electrolytic capacitor, comprising: 3. The method for producing a solid electrolytic capacitor according to claim 1, wherein the cathode terminal is oxygen-free copper. 4. The method for producing a solid electrolytic capacitor according to claim 1, wherein the metal layer is one of gold and copper.