JPH03227006A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To reduce the cost of material, and to contrive reduction in the cost of the title capacitor by a method wherein the outside of a positive lead is composed of valve-action metal, and besides, the inside of the positive lead is composed of the metal other than valve-action metal. CONSTITUTION:For example, tantalum metal powder which functions as a valve is press-molded by burying a part of a binary-constructed positive lead 2, and a molded body 1 is manufactured. The positive lead is composed of binary structure consisting of titanium on the inside and tantalum 4 on the outside. An ingot, consisting of titanium on the inside and tantalum on the outside, is subjected to cold pressure welding and the desired wire diameter is obtained by wire drawing. As the obtained positive lead 2 contains a small quantity of expensive tantalum 4 and a large quantity of inexpensive titanium 3, the cost of material of the anode lead 2 can be reduced. Then, the molded body 1 obtained as above is sintered at a high temperature in vacuum, a dielectric layer, a manganese dioxide layer, a carbon layer and a silver-paste layer are formed thereon successively, and a solid electrolytic capacitor element is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a solid electrolytic capacitor, and particularly to the structure of an anode lead installed in an element.

[Conventional technology]

Conventionally, this type of solid electrolytic capacitor element is made by press-molding a metal powder such as tantalum or niobium having a valve action into a predetermined shape, as shown in FIG. Anode lead 2 made of the same tantalum, niobium, etc.
The molded body with the anode lead 2 planted thereon was sintered in a vacuum at a high temperature of 1000 to 2000°C to form a capacitor element.

[Problem to be solved by the invention]

The conventional solid electrolytic capacitor element described above uses an anode lead wire 2 made of very expensive tantalum or the like.
The material cost of capacitor elements increases, which increases the price of the entire capacitor product and reduces price competitiveness in the market.

In addition, if the anode lead 2 is made thinner or shorter and bent in order to prevent these increases in material costs, the leakage current of the capacitor will increase due to mechanical stress or thermal stress in the subsequent process. The disadvantage is that the reliability of the product deteriorates.

The purpose of the present invention is to make the anode lead thinner and shorter in order to prevent an increase in material costs, and to reduce product reliability due to an increase in capacitor leakage current due to mechanical stress or thermal stress in subsequent processes. Except for the disadvantages that cause deterioration,
The purpose of the present invention is to provide a solid electrolytic capacitor that can reduce material costs and capacitor product prices without changing the thickness or length of the anode lead wire.

[Means to solve the problem]

The solid electrolytic capacitor of the present invention is a capacitor element in which a cathode layer such as a dielectric layer, a semiconductor layer, a graphite layer and a silver paste layer is sequentially deposited on a molded body of valve metal having an anode lead planted thereon. The present invention is characterized in that the outside of the anode lead is made of the valve metal, and the inside is made of a metal other than the valve metal.

According to the present invention, the anode lead planted on the capacitor element has a dual structure in which not only an expensive valve metal such as tantalum is laminated, but also an expensive valve metal is laminated on an inexpensive metal. Therefore, the material cost of capacitor elements can be significantly reduced.

In addition, to reduce material costs, the anode lead is made thinner and more flexible.
Since there is no need to shorten the length, the reliability of the product is improved.

〔Example〕

Hereinafter, the present invention will be explained with reference to the drawings. FIG. 1 is a perspective view of a molded capacitor element according to an embodiment of the present invention. Further, FIG. 2 is a cross-sectional view of an anode lead used in one embodiment of the present invention, and FIG. 3 is a cross-sectional view of a solid electrolytic capacitor according to one embodiment of the present invention.

A part of the anode lead 2 having a dual structure of the present invention is embedded in a metal powder, such as tantalum, which has a valve action, and is press-molded to produce a molded body 1 as shown in FIG.

The anode lead 2 of the present invention has an umbrella diameter of 0 as shown in FIG.
．． It is made of a two-dimensional clad material with a diameter of 1 to 0.5 mm and made of titanium 3 on the inside and tantalum 4 on the outside. Also, the diameter of titanium is approximately 5 mm of the anode lead 2.
0 to 90%.

The manufacturing method involves cold welding an ingot made of titanium on the inside and tantalum on the outside, and then drawing the ingot to a predetermined wire diameter.

The anode lead 2 obtained in this way contains less expensive tantalum 4 and more cheap titanium 3.
The material cost can be reduced by about 50-80%.

Next, the molded body 1 thus obtained is sintered at high temperature in a vacuum, and a dielectric layer, a manganese dioxide layer, a carbon layer, and a silver paste layer are sequentially formed thereon to produce a solid electrolytic capacitor element. do.

Finally, as shown in FIG. 3, from the capacitor element to the anode external lead 5. The cathode external lead 6 is led out and insulated with an exterior resin 7 such as epoxy resin to form a solid electrolytic capacitor.

Although the case where the anode lead 2 has a circular cross section has been described here, it goes without saying that it may have a square or elliptical cross section as shown in FIGS. 4 and 5. Furthermore, it goes without saying that similar effects can be obtained by using Mo or Nb as the metal inside the anode lead 2.

〔Effect of the invention〕

As explained above, the present invention uses an expensive metal such as tantalum only in the outer thin part of the inexpensive metal such as TiMO, so (1) II! The material cost of the extreme card is reduced by more than 50%, which significantly reduces the price of capacitors and promotes cost reduction.

(2) Since there is no need to reduce costs by making the lQi pole lead thinner or shorter, reliability is improved when stress is not applied to the capacitor.

There are effects such as

[Brief explanation of drawings]

FIG. 1 is a perspective view of a capacitor element molded body of the present invention, and FIG.
Figures (a) and (b) are a perspective view and a sectional view of an anode lead of the present invention, Figure 3 is a side sectional view of a solid electrolytic capacitor of the present invention, and Figures 4 and 5 are a perspective view and a sectional view thereof of an anode lead of the present invention. A perspective view of an anode lead of another embodiment, and FIG. 6 is a perspective view of a conventional capacitor element molded body. DESCRIPTION OF SYMBOLS 1... Molded body, 2... Anode lead, 3... Titanium, 4... Tantalum, 5... Anode external lead, 6... Cathode external lead, 7... Exterior resin.

Claims (3)

[Claims] 1. In a capacitor element in which cathode layers such as a dielectric layer, a semiconductor layer, a graphite layer, and a silver paste layer are successively deposited on a molded body of valve metal powder with an anode lead planted thereon, the outside of the anode lead is attached to the valve metal powder. A solid electrolytic capacitor comprising a working metal and an inner side made of a metal other than the valve working metal. 2. The solid electrolytic capacitor according to claim 1, wherein the melting point of the inner metal of the anode lead is 1000° C. or higher. 3. 2. The solid electrolytic capacitor according to claim 1, wherein the valve metal is tantalum, and the metal other than the valve metal is titanium, molybdenum, or niobium.