JPS6017902Y2 - solid electrolytic capacitor - Google Patents

Description

[Detailed explanation of the idea] This proposal concerns the improvement of solid electrolytic capacitors.

In general, this type of solid electrolytic capacitor is made of a capacitor element A made by press-molding metal powder with valve action, such as tantalum, niobium, or aluminum, into a cylindrical shape and sintering it, as shown in Figure 1. A functional metal wire is planted as an anode lead B, a first external lead member C is welded to the protruding portion of this anode lead B, and a second external lead member is coated with an oxide layer on the surface of the capacitor element A. , is connected to the electrode lead layer E formed through the semiconductor layer and the graphite layer using a solder member F, and then the main parts including the capacitor element A are covered with a resin material G. .

By the way, the electrode lead layer E in the capacitor element A is made of a conductive material containing about 50 to 70% silver powder by weight in order to ensure good soldering properties with the second external lead member. However, due to the large amount of silver powder used, although it has excellent characteristics as a capacitor such as impedance and dielectric loss, it has the disadvantage of increasing the cost of the capacitor.

In view of these points, the present invention provides a solid electrolytic capacitor that can effectively reduce costs without significantly sacrificing electrical characteristics.Examples will be described below.

In FIG. 2, reference numeral 1 denotes a capacitor element constructed by press-molding metal powder having a valve action into a cylindrical shape and sintering it.

Reference numeral 2 denotes an anode lead made of a metal wire having a valve action and led out from the capacitor element 1, and in the illustrated example, the anode lead is planted at the center of the metal wire and led out prior to pressure molding of the metal powder. It can also be derived by welding to the circumferential surface of the capacitor element 1.

3 is a first electrode lead layer formed on the circumferential surface of the capacitor element 1 via an oxide layer, a semiconductor layer, and a graphite layer, and is made of a material selected from the group consisting of tin, copper, lead, zinc, iron, chromium, and aluminum. It is composed of a conductive member containing one or more selected metal powders or synthetic powders and resin.

The first electrode extraction layer 3 is made of a suspension of one or more metal powders or alloy powders selected from the group consisting of tin, copper, lead, zinc, iron, chromium, and aluminum, a resin, and a solvent. The capacitor element 1 is immersed in water, pulled up, and then heat-treated.

Reference numeral 4 denotes a second electrode drawing layer formed of a conductive material containing noble metal powder and resin that can be soldered on the first electrode drawing layer 3, and for example, a conductive material containing silver powder and resin. It is composed of

Note that this second electrode extraction layer 4 is formed, for example, similarly to the first electrode extraction layer 3, by immersing the capacitor element 1 in a suspension of silver powder, resin, and a solvent, pulling it up, and then heat-treating it. has been done.

Reference numeral 5 denotes a first external lead member bent into an L shape, for example, and a bent portion 5a thereof is welded to cross the protrusion 2a of the anode lead 2.

Reference numeral 6 denotes a second external lead member having a straight shape, for example, and its inner end is connected to the second electrode lead layer 4 of the capacitor element 1 by a solder member 7.

Reference numeral 8 denotes a resin material which is applied so as to cover the main parts including the capacitor element 1. In addition to the molding method, the outer covering can also be done by a dipping method, a dripping method, etc.

In this way, the electrode lead layer in the capacitor element 1 is composed of the first and second electrode lead layers 3 and 4, and the first electrode lead layer 3 is electrically connected to the graphite layer, and the second electrode lead layer 3 is connected to the graphite layer. The electrode lead layer 4 is electrically connected to the first electrode lead layer 3 and connected to the second external lead member 6 by a solder member 7, respectively.

Therefore, as the conductive material constituting the first electrode extraction layer 3, there is no need to use noble metal powder such as silver, gold, or platinum, which has good soldering properties, but is simply an inexpensive material that can provide good electrical connection. Since metal powder can be used, only the second electrode lead layer 4 may be made of a conductive material whose main component is metal powder of a noble metal such as silver or gold, which has excellent solderability.

For this reason, the proportion of the second electrode extension layer 4 in the electrode extension layer is approximately halved, and the capacitor cost can be significantly reduced.

Furthermore, when the second electrode lead layer 4 in the capacitor element 1 is made of a conductive material containing silver powder and resin, when the second external lead member 6 is soldered thereto,
The silver in the second electrode lead layer is eaten away by the solder member 7, resulting in a defective part, but the first electrode lead layer 3 is interposed between the second electrode lead layer 4 and the graphite layer. Because of this, the defect will not reach the graphite layer.

For this reason, locally the first and second electrode lead layers 3
, 4 is reduced, but the electrical connectivity between the first electrode extraction layer 3 and the graphite layer is not impaired in any way, so that an excellent overall connection state can be obtained.

Therefore, it is possible to obtain practically satisfactory characteristics.

In addition, in conventional capacitors, the thickness of the electrode lead layer is sufficiently thick so that even if the silver in the electrode lead layer is eaten away, the defective part does not reach the graphite layer. Usage is increasing and costs are rising.

Next, specific examples will be described.

An oxide layer, a semiconductor layer, and a graphite layer are formed on the surfaces of a capacitor element made of tantalum powder with a size of 3.5φ×3.7.

This capacitor element is made of 70% tin powder, solvent (butyl acetate) and resin (epoxy resin) by weight.
Immersion in a suspension consisting of 30%.

After pulling it up, it is heated to around 100° C. to remove the solvent and form a first electrode extraction layer.

Furthermore, this capacitor element is made of 70% tin powder, solvent (butyl acetate) and resin (epoxy resin) by weight.
Immersion in a suspension consisting of 30%.

After pulling, heat to around ioo'c to remove the solvent and remove the second
form an electrode extraction layer.

A solid tantalum electrolytic capacitor shown in FIG. 2 is manufactured using a conventional method.

When the characteristics of this capacitor were measured, the results shown in the table below were obtained.

In the table, the electrode lead layer of the conventional product is constructed using the same material as the second electrode lead layer of the present product.

From the table above, the dielectric loss and impedance of this product are slightly worse than the conventional product, but the dielectric loss is usually 10%.
is considered to be the permissible limit, so there is no practical problem at all.

Additionally, the cost of the electrode lead layer can be reduced by half compared to conventional products.

FIG. 3 shows another embodiment of the present invention, in which the capacitor element 1 is formed into a rectangular parallelepiped, and the protrusion 2a of the anode lead 2 led out from the capacitor element 1 has a Z-shaped first external lead. Member 51 is welded.

The second electrode lead layer 4 of the capacitor element 1 has Z
A second external lead member 6 □ is connected with a solder member 7 .

According to this embodiment, the same effects as those of the above-mentioned embodiments can be expected, and when mounting the capacitor on a printed board, workability can be significantly improved since the capacitor can be soldered simply while being placed on the printed board.

FIG. 4 shows a further different embodiment of the present invention, in which the second external lead member is omitted and the solder layers 7, 6□ serve the same purpose.

Note that the present invention is not limited to the above embodiments in any way,
For example, the metal powders in the first electrode extraction layer may be used in combination or in an alloyed state.

Furthermore, if the metal is sensitive to ambient conditions, it can be plated.

As described above, according to the present invention, costs can be effectively reduced without significantly sacrificing electrical characteristics.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional example, and FIGS. 2 to 4 are side sectional views showing different embodiments of the present invention. In the figure, 1 is a capacitor element, 3 is a first electrode extraction layer, and 4 is a second electrode extraction layer.

Claims (1)

[Scope of utility model registration request] In a capacitor element made of a metal powder having a valve action, an electrode extraction layer as a cathode is formed on the circumferential surface of the capacitor element through an oxide layer, a semiconductor layer, and a graphite layer.
The electrode drawing layer is divided into a first electrode drawing layer and a second electrode drawing layer, and the first electrode drawing layer is made of one or more metal powders selected from the group consisting of tin, copper, lead, zinc, iron, chromium, and aluminum. Or a conductive member containing alloy powder and resin, the first
A solid electrolytic capacitor characterized in that a second electrode extension layer on the electrode extension layer is formed of a conductive member containing solderable noble metal powder and resin.