JPS5963716A - Manufacturing method of solid electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing solid electrolytic condensate.

In conventional solid tantalum electrolytic capacitors, an oxide film that becomes a dielectric is formed on the surface of the anode body made by molding and sintering tantalum powder, which is a valve metal, through anodization, and a semiconductor layer is formed on the oxide film. A manganese dioxide layer is formed, a carbon layer is formed on top of this semiconductor layer, a 2N electroconductive coating containing fine silver powder is applied and cured, and a cathode terminal is soldered to it. I'm pulling it out.

In such prior art, when soldering the terminals, the silver in the conductive PFri paint layer dissolves into the solder, reducing the conductivity of the cathode layer and, as a result, changing the electrical characteristics of the capacitor, i.e., the impedance. , equivalent series resistance, and tan δ deteriorated.

An object of the present invention is to provide a method for manufacturing electrolytic capacitors without deteriorating electrical characteristics and without using expensive silver paint.

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

FIG. 1 is a sectional view of a solid electrolytic capacitor element according to an embodiment of the present invention. The anode body 1 is made by pressurizing tantalum powder, molding it, and then sintering it. A lead wire 2 is drawn out from this body 1.

Lead wire 2 is, for example, a tantalum wire. On the surface of this anode body 1, an oxide film 3 which becomes a dielectric is formed by chemical conversion treatment.

Next, a manganese dioxide layer 4, which is a semiconductor layer, is formed on the surface by a known technique. A first carbon layer 5a is formed on the negative side of this semiconductor layer 4. the first carbon layer 5a with
penetrates into the porous semiconductor layer 4, and therefore the semiconductor layer 4 and the bond layer 5a come into contact with a low resistance, maintaining good conductivity between them.

A second carbon layer 5b is further formed on the first carbon layer 5a. The second carbon layer 5b has a composition that prevents the plating solution from penetrating when the anode body is immersed in the plating solution to form a metal plating layer in a later step. If the first carbon layer 5a cannot prevent the plating solution from penetrating
If a capacitor element having only the above-mentioned electrolytic capacitor is immersed in a plating solution, the plating solution will penetrate into the semiconductor layer 4 through the first carbon layer 5a, and the characteristics of the electrolytic capacitor will deteriorate. If the plating solution penetrates, 1. Normally, the plating solution is washed away, but what happens if the plating solution penetrates into the body layer and the inside of the porous anode body? 7+&;l
: It was difficult, took a long time, and was incomplete. In the present invention, since the second carbon layer 5b is formed on the first carbon layer 5a, the plating solution is applied to the first carbon layer 5a.
It is prevented from penetrating into the semiconductor layer 4 from a.

The first carbon layer 5a is obtained by applying and drying a mixture of graphite, a binder containing a small amount of binder, and the resin components from 1 to 1 dispersed in water, and drying the second carbon layer 5513 kl.
: Contains graphite and heat-resistant resin component (P"3 melt iI)
, j was applied and heat cured. In addition, 1. The details of this case: and the 1st and 2nd in the drawings.
The carbon layers 5a and 5b will be collectively designated by the reference numeral 5.

The capacitor element on which this carbon layer 5 has been formed is immersed in a hot lightning-decomposed nickel plating solution to form a nickel plating layer 6.

Although not shown, a cathode terminal is soldered to this plating layer 6 and pulled out. Also, the anode terminal is welded to the lead &i12 and pulled out. Then, if necessary, the capacitor is completed by enclosing it in a metal case 2 or by applying a synthetic resin exterior.

In the conventional technique, a conductive paint containing fine silver particles is applied onto the carbon layer 5a, and a cathode terminal is soldered to the layer. In such prior art, the silver particles in the conductive paint layer were not eaten into the solder, so the conductivity of the conductive paint layer decreased and the characteristics of the capacitor deteriorated. . 1. In order to prevent this, expensive silver-containing solder has been used in the past, but it has not been possible to completely prevent the above phenomenon. Furthermore, when soldering the cathode terminal, if the conventional silver paint layer gets too hot, more silver will melt into the solder, so strict limits must be placed on the soldering temperature and time.

However, in the present invention, since the metal plating layer 6 is used as the cathode,
These temperature and time restrictions did not have to be as severe as in the case of silver paint layers, thus making the work easier. In this embodiment, a nickel plating layer 6 is formed, but other metals such as copper may be plated.

A second embodiment of the invention is shown in FIG. Anodic oxide film 3
A heat-resistant and electrically insulating synthetic resin layer 7 is coated on the surface of the anode body 1 on which the lead wires 2 are drawn out. Thereafter, similarly to the first embodiment, a semiconductor layer 4, a first carbon layer 5a, and a second carbon layer 5b are sequentially formed, and then a metal plating layer 6 is formed. In this embodiment, the periphery of each of the semiconductor layer 4, carbon layer 5, and metal plating layer 6 is formed in contact with the synthetic 4R11 fat layer 7. That is, since these layers 4, 5, and 6 are formed with a uniform thickness over the entire surface of the anode body 1, the semiconductor layer 4 of the plating solution is
Penetration is reliably prevented. That is, when immersing in the plating solution to form the plating layer 6, the liquid level must be carefully adjusted so that the plating layer 6 does not go beyond the second carbon layer 5b'5c and directly touch the first carbon layer 5a or the semiconductor layer 4. There is no need to manage it.

Since it is only necessary to prevent the plating liquid level from exceeding the synthetic resin layer and touching the lead wire 2, the liquid level can be easily adjusted.

The formation of the SHOEI conductor layer 4 is an anodic oxide film; (formation of) 1
．． The anode body 1 is immersed in an aqueous manganese nitrate solution and converted into a manganese dioxide layer by thermal decomposition, which is repeated several times. The synthetic resin layer 7 shown in the second figure is formed by this operation from 2 to 3.
It may be applied after repeating three times.

As described above, according to the present invention, since silver paint or silver-containing solder is not used, the cost is low, and there is no risk of deterioration of the sharp bending characteristics due to the silver curling phenomenon during soldering. Furthermore, since the metal plating layer is used, the present invention does not require strict control to control the temperature during soldering for one hour, as is the case when forming a conventional silver paint layer. Therefore, manufacturing of capacitors has become easier. Furthermore, a first carbon layer is formed on top of the semiconductor layer in contact with a low resistance, a second carbon layer is provided on top of that to prevent penetration of the plating solution, and a metal plating layer is formed on top of that, so that after plating This eliminates the need for a long period of cleaning, and prevents the plating solution from penetrating into the semiconductor layer and the like, thereby preventing deterioration of the capacitor's mechanical characteristics. Capacitors manufactured by this method can be used at higher temperatures than those using silver paint.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a capacitor element according to one embodiment of the present invention, and FIG. 2 is a sectional view of a capacitor element according to another embodiment. ■... Anode body, 3... Oxide film, 4... Semiconductor layer,
5a... ml carbon layer, 5b... second carbon layer,
6...Nickel plating layer, 7...Synthetic resin layer Agent Patent Attorney Kei Nishi Part'1,~23 4

Claims (1)

[Claims] +1+ A semiconductor layer is formed on the oxide film of the anode body, which is made of a valve metal and has a dielectric oxidizer film formed by anodization. A first carbon layer in contact with the carbon layer is formed, a second carbon layer is formed on the first carbon layer to prevent penetration of a plating solution, and a core metal plating layer serving as a cathode layer is formed on top of the second carbon layer. A method for manufacturing solid electrolytic capacitor. (2. In the method for manufacturing a solid electrolytic capacitor as set forth in claim 1, a side heat-resistant and electrically insulating composite is applied to the surface of the anode body on which the dielectric oxide film is formed, from which the lead wire is drawn out. A method characterized in that a resin layer is formed, and the peripheries of each of the semiconductor layer, first carbon layer, v-bond layer, and metal plating layer that are formed thereafter are in contact with the synthetic resin layer. .