JPH07201658A - Tantalum solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To protect a tantalum solid electrolytic capacitor against burning due to Joule's heat upon short circuit. CONSTITUTION:A manganese dioxide layer 4, a carbon layer 5 and a cathode conductive layer 6 are formed sequentially on an anode 1 having a lead wire 2 with a dielectric oxide film 3 being formed on the surface. A conductive layer 7, which is rendered dielectric by heat, is formed between the carbon layer 5 and the cathode conductive layer 6. Upon occurrence of short circuit, the resistance of the conductive layer 7 is increased by the Joule's heat to render the conductive layer 7 dielectric thus suppressing undue heating and protecting the capacitor against burning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tantalum solid electrolytic capacitor, and more particularly to a novel tantalum solid electrolytic capacitor provided with means for preventing a burnout accident due to Joule heat generation at the time of short circuit.

[0002]

2. Description of the Related Art As is well known, a semiconductor is provided on an anode body 1 having an anode lead wire 2 such as a tantalum wire and a dielectric oxide film 3 formed on the surface of a sintered body of tantalum powder. A conventional tantalum solid electrolytic capacitor having a structure in which a manganese dioxide layer 4 as a substrate, a carbon layer 5 such as graphite, and a cathode conductive layer 6 of a silver paste are sequentially laminated.
6) is short-circuited, Joule heat is generated by the flowing current. On the other hand, the anode 2 mainly composed of the tantalum sintered body has an effective surface area much larger than the apparent surface area.
When it exceeds 00 ° C, it burns explosively. For this reason, there is a risk that the tantalum solid electrolytic capacitor is short-circuited and burns out if the amount of heat generated at that time is large, and the circuit board or, in the worst case, the electronic device itself.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art. The object of the present invention is to provide heat insulation between the carbon layer and the cathode conductive layer. An object of the present invention is to provide a highly reliable tantalum solid electrolytic capacitor capable of preventing burnout due to Joule heat generation at the time of short circuit by forming a conductive layer that becomes solid.

[0004]

To this end, the present invention provides a semiconductor layer, a carbon layer and a cathode conductive layer on an anode body having an anode lead wire and having a dielectric oxide film formed on the surface thereof. A tantalum solid electrolytic capacitor in which layers are sequentially laminated is characterized in that a conductive layer that is thermally insulated is formed between a carbon layer and a cathode conductive layer.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings and its operation. As shown in FIG. 1, the present invention relates to a tantalum solid electrolytic capacitor having the structure described in the section of the prior art, in which a conductive layer that is thermally insulated is provided between the carbon layer 5 and the cathode conductive layer 6. 7 is formed.
The conductive layer 7 which is insulated by heat is made by dispersing conductive particles such as carbon and silver in an insulating resin such as polyolefin and fluororesin, and is dried and cured by a solvent.
It is made by thermosetting, pressure molding, etc., and at a temperature lower than 300 ° C., conductive particles are in contact with each other to form a conductive passage to maintain conductivity as a whole, and at a temperature higher than 300 ° C., an insulating resin is It melts and expands, cutting off the contact between the conductive particles and insulating the whole. Therefore, when the tantalum solid electrolytic capacitor is short-circuited, the Joule heat generated thereby increases the resistance, and the conductive layer 7 is insulated by heat.
Is insulated, excessive heat generation at the time of short circuit is suppressed, and burnout accident is prevented.

[0006]

According to the present invention, however, since the conductive layer 7 which is insulated by heat is provided between the carbon layer 5 and the cathode conductive layer 6, excessive heat generation during a short circuit is suppressed. Therefore, a burnout accident is prevented and the safety is excellent.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an example of a tantalum solid electrolytic capacitor according to the present invention.

FIG. 2 is a vertical sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode body 2 Anode lead wire 3 Dielectric oxide film 4 Manganese dioxide layer 5 Carbon layer 6 Cathode conductive layer 7 Conductive layer insulated by heat

Claims (1)

[Claims] 1. A tantalum solid electrolytic capacitor in which a semiconductor layer, a carbon layer, and a cathode conductive layer are sequentially laminated on an anode body having an anode lead wire and having a surface on which a dielectric oxide film is formed, A tantalum solid electrolytic capacitor, characterized in that a conductive layer which is insulated by heat is formed between the carbon layer and the cathode conductive layer.