JPH05121278A - Chip-shaped solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To provide a title capacitor excellent in volume efficiency and in reliability and economy with no packaging failure. CONSTITUTION:On the top and the bottom of a capacitor with a cathode conductor layer 3, a heat-resistant insulating resin plate 4 (polyimide) having electrode terminals 5a, 5b different in thickness on both ends keeps the thick electrode terminal 5b connected to an anode lead 2 by a conductive adhesive 6, and the other thin electrode terminal 5a connected to the cathode conductor layer 3 electrically and mechanically. This design dispenses with use of external electrode leads, so that tomb stone phenomenon upon component packaging can be prevented because of excellent volume efficiency and high precision of electrode terminal shape; further, because of a thick electrode terminal on the side connected to an anode lead, connection reliability is high, and so is economy effect.

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 with improved volume 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 electrode leads are attached to both ends of a capacitor element shown in FIG. A simple resin coating type is used, in which a simple resin coating is applied by a method such as electrostatic coating and then external terminal electrodes consisting of a conductive paste, a nickel plating layer, and a solder layer are formed on both ends of the element without using external positive / cathode leads. is there.

[0003]

As shown in FIG. 4, the conventional resin-molded chip solid electrolytic capacitor has external positive / cathode leads 22 and 23 connected to the capacitor element 21, so that it can be made compact and thin. It was difficult.

Further, in the case of molding resin packaging, there is a drawback 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 exterior type chip-shaped solid electrolytic capacitor. As shown in FIG. 5, the external positive / negative terminals 31, 32 can be formed directly from both ends of the element without using external electrode lead-outs, so that the resin mold type can be made smaller and thinner. It will be possible.

However, a part of the cathode conductor layer may be exposed after resin coating on the peripheral surface of the element by electrostatic coating or the like.
There is a problem in mass production because the process such as forming the external positive and negative terminals from the three layers of the conductive layer, the plating layer and the solder layer is complicated.

Further, since the conductive layer is formed by silver paste or the like, the shape of the external positive / cathode terminals varies, which may cause a connection failure with the pattern of the circuit board during mounting of the component, or one side of the capacitor may float. There were problems such as stones.

The object of the present invention is to eliminate the drawbacks of the prior art, to be excellent in volumetric efficiency, to be highly precise in the shape of electrode terminals, and to prevent the tombstone phenomenon during the mounting of parts. It is intended to provide a chip-shaped solid electrolytic capacitor that can achieve the desired effect.

[0009]

A chip-shaped solid electrolytic capacitor of the present invention comprises a solid electrolytic capacitor element comprising an anodic oxide film layer, a solid electrolyte layer and a cathode conductor layer which are sequentially formed on an anode body having an anode lead. 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, wherein the electrode terminals are formed thick only on the side connected to the anode lead. It is characterized by being

[0010]

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a chip solid electrolytic capacitor according to an 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 in which anode leads 2 are erected is formed on the anode conductor layer composed of an anodized film layer, a manganese dioxide layer, and a silver paste in order by well-known means. 3 is formed.

Next, as shown in FIG. 2, a thickness of 0.1 mm,
At 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, a copper foil having a thickness of 15 μm and electrode terminals 5a, 5b made of a solder having a thickness of 5 μm are provided.
To form. At this time, only the side connected to the anode lead 1
Electrode terminals are formed thick by using a copper foil of 00 micron.

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 to each other with a conductive adhesive material 6 such as silver paste.

Next, the anode lead 2 protruding from the insulating resin plate 4 is cut to form a chip solid electrolytic capacitor. Table 1 shows the height dimensions of the chip tantalum capacitor of 16 V and 6.8 μF thus formed and the mounting test results. We also compared the resin-molded type, in which the capacitor element was formed using the same material and the same method, with a simple resin-coated chip tantalum capacitor.

[0015]

[Table 1]

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

FIG. 3 is also a sectional view of another embodiment of the chip solid electrolytic capacitor of the present invention. By coating the void portion on the lead surface of the anode lead with the insulating resin 17 such as epoxy resin, the connection reliability between the anode lead 12 and the electrode terminal 15b can be improved.

[0018]

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

[Brief description of drawings]

FIG. 1 is a sectional view of an 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 one 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-shaped solid electrolytic capacitor.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode body 2,12 Anode lead 3 Cathode conductor layer 4 Heat-resistant insulating resin plate 5a, 5b, 15b Electrode terminal 6 Conductive adhesive 21 Capacitor element 22 External anode lead 23 External cathode lead 31 Anode terminal 32 Cathode terminal

Claims (1)

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