JP2738183B2 - Chip-shaped 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 chip solid electrolytic capacitor, and more particularly to an external electrode structure having improved volumetric efficiency.

[0002]

2. Description of the Related Art A conventional chip-shaped solid electrolytic capacitor includes a resin mold type in which external positive and negative leads are attached to both ends of a capacitor element shown in FIG. A simple resin package is formed by forming a simple resin package using a method such as electrostatic coating, and then forming external terminal electrodes consisting of a conductive paste, nickel plating layer, and solder layer at both ends of the element without using external positive and negative leads. is there.

[0003]

As shown in FIG. 4, a conventional resin-molded chip-type solid electrolytic capacitor has external and positive leads 22 and 23 connected to a capacitor element 21 so that it can be reduced in size and thickness. It was difficult.

[0004] In addition, in the case of using a molded resin sheath, there is a disadvantage that it is not possible to flexibly cope with a change in shape because an expensive mold is used.

In order to solve these drawbacks, there is a simple resin-encased chip-shaped solid electrolytic capacitor. As shown in FIG. 5, external positive / negative terminals 31, 32 can be formed directly from both ends of the element without using external electrode lead-outs, as shown in FIG. It becomes possible.

[0006] However, after covering the element peripheral surface with a resin by electrostatic coating or the like, a part of the cathode conductor layer is exposed,
The process is complicated, such as the formation of external positive and negative terminals from three layers of the conductive layer, the plating layer, and the solder layer, and there is a problem in mass production.

Further, since the conductive layer is formed by silver paste or the like, the shape of the external positive / negative terminal varies, which causes a connection failure with the pattern of the circuit board at the time of component mounting, or a tomb in which one side of the capacitor floats. There were also problems such as stones.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the conventional disadvantages, to achieve excellent volumetric efficiency, to achieve high electrode terminal shape accuracy, to prevent the occurrence of a tombstone phenomenon at the time of component mounting, and to further improve the reliability and economy of connection. It is an object of the present invention to provide a chip-shaped solid electrolytic capacitor capable of obtaining a positive effect.

[0009]

According to the present invention, there is provided a solid electrolytic capacitor chip comprising a solid electrolytic capacitor element comprising an anodic oxide film layer, a solid electrolyte layer, and a cathode conductor layer formed sequentially on an anode body having an anode lead. In a chip-shaped solid electrolytic capacitor connected to the upper and lower surfaces of the capacitor element and made of a heat-resistant insulating resin plate having electrode terminals at both ends, the electrode terminals are formed thick only on the side connected to the anode lead. It is characterized by being.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a chip-shaped solid electrolytic capacitor according to one embodiment of the present invention, and FIG. 2 is a sectional view of a heat-resistant insulating resin plate used in the embodiment of the present invention.

As shown in FIG. 1, an anode body 1 made of tantalum metal having an anode lead 2 planted thereon is successively formed by a well-known means on an anode oxide layer, a manganese dioxide layer, and a cathode conductor layer made of silver paste. 3 is formed.

Next, as shown in FIG.
On both ends of a heat-resistant insulating resin plate 4 made of a polyimide resin having a length of 3.2 mm and a width of 1.6 mm, electrode terminals 5a and 5b made of a 15-micron-thick copper foil and a 5-micron solder are provided.
To form At this time, only the side connected to the anode lead is 1
The electrode terminals are formed thick using a copper foil of 00 microns.

Next, the electrode terminal 5a and the cathode conductor layer 3 are
The electrode terminal 5b and the anode lead 2 are electrically and mechanically connected by a conductive adhesive 6 such as a silver paste.

Next, the anode lead 2 protruding from the insulating resin plate 4 is cut to form a chip-shaped solid electrolytic capacitor. Table 1 shows the height dimensions and mounting test results of the 16 V, 6.8 μF chip tantalum capacitor thus formed. In addition, a comparison was made between a resin mold type in which the capacitor element was formed using the same material and the same method, and a simple resin exterior chip tantalum capacitor.

[0015]

[Table 1]

The thickness is an average value of n = 50 pieces, and the mounting failure rate is n = 10,000 tombstones in a mounting test of 10,000 pieces.
Shows the total soldering failure rate.

FIG. 3 is also a sectional view of another embodiment of the solid electrolytic capacitor chip according to the present invention. The connection reliability between the anode lead 12 and the electrode terminal 15b can be improved by coating the gap of the anode lead lead-out surface with an insulating resin 17 such as an epoxy resin.

[0018]

As described above, the present invention has the following effects by electrically and mechanically connecting heat-resistant insulating resin plates having different electrode terminals to capacitor elements. (1) Compared with the conventional resin mold type, external electrode lead-outs are not required, so that the size and thickness can be reduced. or,
Since an expensive mold is not required, it is possible to flexibly cope with a change in chip shape. (2) The process can be simplified as compared with the conventional simple resin exterior type, and the dimensional accuracy of the external electrode terminals is high, so that the tombstone phenomenon that occurs at the time of mounting the printed wiring board can be improved. (3) Since the electrode terminal on the side connected to the anode lead is formed to be thick, an expensive silver paste for electrically connecting the anode lead and the electrode terminal can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIG. 2 is a cross-sectional view of a heat-resistant insulating resin plate having electrode terminals having different thicknesses at both ends used in an embodiment of the present invention.

FIG. 3 is a sectional view of another embodiment of the present invention.

FIG. 4 is a sectional view of an example of a conventional resin-molded chip solid electrolytic capacitor.

FIG. 5 is a cross-sectional view of an example of a conventional simple resin-encapsulated chip solid electrolytic capacitor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 anode body 2, 12 anode lead 3 cathode conductor layer 4 heat-resistant insulating resin plate 5 a, 5 b, 15 b electrode terminal 6 conductive adhesive 21 capacitor element 22 external anode lead 23 external cathode lead 31 anode terminal 32 cathode terminal

Claims (1)

(57) [Claims] 1. A solid electrolytic capacitor element comprising an anodic oxide film layer, a solid electrolyte layer, and a cathode conductor layer formed sequentially on an anode body having an anode lead, and two ends connected to the upper and lower surfaces of the capacitor element. A chip-shaped solid electrolytic capacitor comprising a heat-resistant insulating resin plate having electrode terminals, wherein the electrode terminals are formed thick only on a side connected to an anode lead.