JPS6236374B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to solid electrolytic capacitors, and particularly to improvements in solid electrolytic capacitors using resin for the exterior.

Conventionally, this type of solid electrolytic capacitor is manufactured by forming a dielectric layer 2 by chemically converting an anode body 1 made of a metal with valve action such as tantalum, aluminum, or niobium, as shown in FIG. A semiconductor layer 3 and a cathode layer 4 are formed, an external lead wire 5 is connected to the cathode layer, and the outer peripheral surface thereof is covered with resin.

However, solid electrolytic capacitors packaged with resin cannot prevent moisture and impurities from getting in, and the product's electrical characteristics (capacitance change, dielectric loss tangent, leakage current, etc.) deteriorate during humidity tests.

An object of the present invention is to provide a solid electrolytic capacitor that solves the above-mentioned conventional drawbacks.

According to the present invention, there is obtained a solid electrolytic capacitor characterized in that the anode body lead portion is coated with an insulating material, and the entire capacitor element except the anode body lead portion is coated with a low melting point metal layer.

This embodiment will be explained below with reference to FIGS. 2 and 3.

In Fig. 2, reference numeral 1 indicates an anode body produced by press-molding powders of tantalum, aluminum, niobium, etc. and then sintering them in a high-temperature vacuum, and 2 indicates an anode body produced by chemical conversion treatment of the anode body 1 in an electrolyte such as phosphoric acid. It is a dielectric layer of metal oxide. 3 is a semiconductor layer such as manganese dioxide, which is deposited, for example, by thermal decomposition of manganese nitrate. Reference numeral 4 denotes a cathode layer made of metal such as solder formed on the entire outer peripheral surface of the semiconductor layer 3, an external lead wire 5 is connected to this cathode layer 4, and an anode body lead 7 led out from an anode body such as tantalum wire and the cathode. layer 4
The periphery of the implanted base of the anode lead 7 is covered with an insulator 8 such as butadiene resin to prevent direct contact between the anode lead 7 and the anode body lead 7. Reference numeral 6 is an exterior insulating material such as epoxy resin or silicone resin applied by a molding method or dip method, and reference numeral 9 is an anode external lead wire welded to the tip of the anode body lead 7.

In this embodiment, the anode lead 7 was covered with the insulator 8 after the semiconductor layer 3 was formed, but the anode lead 7 was covered with the insulator 8 before the dielectric layer 2 was formed (FIG. 3) or before the semiconductor layer 3 was formed. There is no problem even if the lead 7 is covered with the insulator 8. In addition, as shown in Figure 4, the conventional construction method (first
After attaching the anode lead wire through the cathode layer 4, the entire capacitor element is covered with an insulator 8, and then from above the insulator 8, the adhesion with at least one of the lead wires is removed. Alternatively, a method of covering the entire capacitor element with a second solder layer 10 coated with a silver paste layer or the like would not depart from the spirit of the present application. In this case, the cathode layer 4 need not be made of metal, and it goes without saying that a conductive adhesive or the like may be used. Further, in this embodiment, butadiene resin is used as the insulator 8, but it goes without saying that an inorganic insulator such as epoxy resin, silicone resin, or glass may also be used.

Next, the temperature of tantalum solid electrolytic capacitors manufactured by the present invention and the conventional method is 85.
Figure 5 shows the change in capacitance over time, Figure 6 shows the change in dielectric loss tangent, and Figure 7 shows the change in leakage current in a high temperature and humidity test at 95% RH and 95% humidity. The vertical axis in FIG. 7 shows a logarithmic scale. As shown in FIGS. 5, 6 and 7, it can be seen that the products manufactured according to the present invention have significantly improved high temperature and humidity resistance properties.

As described above, according to the present invention, at least the area around the implanted base of the anode body lead is covered with an insulating material, and the entire capacitor element except for the anode body lead is covered with a metal layer, so that moisture, impurities, etc. can be removed from the capacitor element. It is possible to significantly reduce the intrusion into the capacitor and suppress the deterioration of the electrical characteristics of the capacitor.
It is possible to provide a solid electrolytic capacitor with great practicality and reliability.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of the conventional product, Figures 2, 3,
FIG. 4 is a side sectional view showing an embodiment of the present invention.
FIGS. 5, 6, and 7 are graphs showing changes over time in capacitance, dielectric loss tangent, and leakage current, respectively, in a high-temperature humidity test of the product according to the present invention and a conventional product. 1: anode body, 2: dielectric layer, 3: semiconductor layer,
4: Cathode layer, 5: (Cathode) external lead wire, 6: Exterior insulation material, 7: Anode body lead, 8: Insulator, 9:
(Anode) External lead wire. 10: Solder layer.

Claims (1)

[Claims] 1. In a solid electrolytic capacitor in which a dielectric layer, a semiconductor layer, and a cathode layer are sequentially formed on an anode body made of a metal having a valve action and the anode body is packaged with resin, at least the anode body lead portion is covered with an insulator, and the anode A solid electrolytic capacitor characterized by covering the entire capacitor element except for the body leads with a solder layer.