JPH104032A - Multi-terminal solid-state electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a solid-state electrolytic capacitor from being wrongly mounted with reverse polarity by a method wherein an anode lead-out wire is implanted in metal fine powder as buried so as to penetrate through a pellet of metal fine powder later, the metal fine powder is compression-molded and sintered into a porous pellet, and an oxide layer, a manganese dioxide layer, a carbon layer, and a paste layer are successively formed on the surface of the porous pellet. SOLUTION: An anode lead-out wire 1 is implanted in metal fine powder as buried so as to penetrate through a pellet of metal fine powder later, the metal fine powder is compression-molded into a pellet. Then, the pellet is sintered into a porous pellet 2, and a spacer 23 of fluororesin is provided to the base of the porous pellet 2 so as to prevent the root of the anode lead-out wire which penetrates through the pellet 2 from getting excessively wet with the material of a cathode when the cathode is formed. Then, a dielectric oxide film is formed on the surface of the porous pellet 2, a manganese dioxide semiconductor layer 24 is formed on the dioxide film, a carbon cathode layer 25 is provided onto the semiconductor layer 24, and a silver paste layer is formed thereon for the formation of a solid-state electrolytic capacitor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-terminal solid electrolytic capacitor.

[0002]

2. Description of the Related Art In a conventional solid electrolytic capacitor, as shown in FIG. 4, an anode lead wire 21 is buried in a metal powder having a valve action, and the metal powder having a valve action is compressed by a press into pellets. In order to prevent the base of the anode lead wire 21 of the porous pellet 22 obtained by sintering the pellet from being wetted more than necessary by the raw material liquid at the time of forming the cathode, the base of the anode lead wire 21 of the porous pellet 22 is required. The spacer 23 made of fluororesin is installed.

Next, an oxide film, which is a dielectric, is formed on the surface of the porous pellet 22. The porous pellet 22, on which the oxide film has been formed, is immersed in a manganese nitrate solution, and is then subjected to a heat treatment to perform manganese dioxide as a semiconductor layer. The layer 24 is formed.
Next, a carbon layer 25 serving as a cathode layer and a silver paste layer 26 are sequentially formed on the surface of the manganese dioxide layer 24 to obtain a solid electrolytic capacitor element 27.

An external electrode 28 which is a lead frame is attached to the solid electrolytic capacitor element 27, and is used as an anode external electrode 28A and a cathode external electrode 28B, respectively. Next, the exterior 29 is formed by transfer molding using an epoxy resin, and then the lead frame as the external electrode 28 is attached to the exterior 2.
Forming is performed along 9 to obtain a solid electrolytic capacitor.

[0005]

As shown in FIG. 4, the external electrodes of the conventional solid electrolytic capacitor are porous pellets 22.
An external electrode 28 made of a lead frame is attached to the tip of the anode lead wire 21 that is led out by resistance welding 30 to form an anode external electrode 28A. An external electrode 28 is attached to the surface of the silver paste layer 26 of the solid electrolytic capacitor element 27 with a conductive adhesive 31 to form a cathode external electrode 28B.

However, according to this conventional structure, since the external electrode 28 has polarities on the anode external electrode 28A and the cathode external electrode 28B, when mounting the solid electrolytic capacitor on the printed wiring board, the polarity is reversed. In many cases, this would lead to a major accident such as burning of the solid electrolytic capacitor. A fuse in which a fuse is inserted between the external electrode 28 and the solid electrolytic capacitor element 27 has been put to practical use so that even if the polarity is reversed, a large accident such as burnout does not occur. But,
This method of inserting a fuse has low reliability. The man-hour required to insert a fuse between the solid electrolytic capacitor element 27 and the external electrode 28 increases the cost of the solid electrolytic capacitor. There were drawbacks such as these, and it was a big problem.

[0007]

In order to solve the above-mentioned problems, as shown in FIG. 1, an anode lead wire 1 penetrating a pellet is implanted in a metal fine powder having a valve action and compression-molded. Into pellets. Next, after sintering the pellet to form a porous pellet 2, the base of the anode lead wire 1 penetrating the pellet is prevented from being wetted more than necessary by the raw material at the time of forming the cathode. A co-spacer 23 made of fluororesin is installed at the root.

Next, an oxide film as a dielectric is formed on the surface of the porous pellet 2, and a manganese dioxide layer 24 as a semiconductor layer is formed on the oxide film. Next, a carbon layer 25 serving as a cathode layer and a silver paste layer 26 are sequentially formed on the manganese dioxide layer 24 to obtain a solid electrolytic capacitor 3. An external electrode 4 made of a lead frame is attached to the left and right ends of the anode lead wire 1 penetrating from the solid electrolytic capacitor element 3 by resistance welding 30 to form an anode external electrode 4A.
And Next, as shown in FIG. 2, the surface of the silver paste layer 26 of the solid electrolytic capacitor element 3 and the external electrode 4 made of a lead frame are attached with a conductive adhesive 31 to form a cathode external electrode 4B.

In the present invention, as shown in FIGS. 1 and 2, the anode external electrode 4A is led out from both the left and right sides of the outer casing 29 of the solid electrolytic capacitor, and the cathode external electrode 4B is 90% of the anode external electrode 4A.
Since it was derived from the ° direction, there was no mounting with the polarity reversed, and there was no major accident at the time of burning.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described by taking a chip type tantalum solid electrolytic capacitor as an example. As shown in FIG.
Pellet 5 through which anode lead wire 1 made of tantalum wire having a diameter of 0.25 mm and penetrating through 13.5 mg of fine tantalum metal powder
Is manufactured by compression molding. Next, as shown in FIG. 1, the pellet 5 through which the anode lead-out wire 1 penetrates is sintered in a vacuum at a temperature of 1600 ° C. to obtain a porous pellet 2 of 1.1 × 1.7 × 1.1 mm. Next, as shown in FIG. 5, one end of the anode lead wire 1 derived from the porous pellet 2 is attached to the side end of the stainless steel strip 6 by welding, so that the process can be performed easily. .

Next, the porous pellets 2 attached to the stainless steel strip 6 are immersed in a 0.1% phosphoric acid solution, and a voltage of about 65 V DCC is applied between the stainless steel strip 6 and the phosphoric acid solution. Is applied to form an oxide film as a dielectric. Next, as shown in FIG. 1, the porous pellet 2 on which an oxide film as a dielectric is formed is held in an atmosphere of 35 ° C. so that the lead wire 1 passing through the anode becomes horizontal.
After the manganese nitrate solution is dropped and impregnated using a dispenser, the manganese nitrate solution is thermally decomposed in a humidified atmosphere at 230 ° C. The operation of dropping and impregnating the manganese nitrate solution → pyrolysis is repeated 10 times to form a manganese dioxide layer 24 as a semiconductor layer as shown in FIG.

Next, a carbon layer 25 serving as a cathode layer and a silver paste layer 26 are sequentially formed on the surface of the manganese dioxide layer 24 to obtain a solid electrolytic capacitor element 3. Next, the solid electrolytic capacitor element 3 is separated from the stainless steel strip 6 and placed on a lead frame 8 as shown in FIG. 6, and the tip of the penetrating anode lead wire 1 is resistance-welded to the positive electrode lead 9 and goes directly to this The silver paste layer 26 of the solid electrolytic capacitor element 3 is attached to the negative electrode lead 10 provided in the direction in which the conductive paste 31 is provided, as shown in FIG. Note that the oxide film formed on the anode lead wire 1 penetrating before performing the resistance welding 30 was mechanically scraped off only at the welded portion to improve the reliability of welding.

Next, the lead frame 8 on which the solid electrolytic capacitor element 3 was mounted was inserted into a transfer mold, and the exterior 29 was made of epoxy resin. Next, unnecessary portions of the lead frame 8 are cut off, and as shown in FIG. 1, the external electrodes 4 as the positive electrode leads 9 are formed along the outer package 29 to form the anode external electrodes 4A. Next, as shown in FIG. 2, the external electrode 4, which is the negative electrode 10, is formed along the exterior 9 to form a cathode external electrode 4B. The external dimensions of the chip-type tantalum solid electrolytic capacitor obtained above are 3.4 × 2.6 × 1.9 mm, and the rated voltage is 16. V
DC and capacitance were 6.8 μF.

[0014]

As described above, the present invention has the following advantages. Because of the non-polar structure, there was no major accident such as burning due to the conventional reverse mounting. The cost has been reduced by 10 to 15% since the man-hour for inserting the fuse is no longer required.

[Brief description of the drawings]

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

2 is a cross-sectional view of A-A ¹ of the present invention.

FIG. 3 is a perspective view showing a pellet of the present invention.

FIG. 4 is a conventional sectional view.

FIG. 5 is a perspective view showing a state where the pellet of the present invention is attached to a stainless steel strip.

FIG. 6 is a lead frame used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Penetrating lead wire 2 ... Porous pellet 3 ... Solid electrolytic capacitor element 4 ... External electrode 4A ... Anode external electrode 4B ... Cathode external electrode 5 ... Pellet 6 ... Stainless steel strip 7 ... Side surface 8 ... Lead frame 9 ... Positive electrode lead 10 ... Negative electrode lead 21 ... Anode lead wire 22 ... Porous pellet 23 ... Spacer 24 ... Manganese dioxide layer 25 ... Carbon layer 26 ... Silver paste layer 28 ... External electrode 28A ... Anode external electrode 28B ... Cathode external electrode 29 ... exterior 30 ... resistance welding 31 ... conductive adhesive

Claims (1)

[Claims] 1. A metal powder having a valve action, in which an anode lead wire is implanted, is compressed into a compact, then sintered to form a porous pellet, and an oxide film, manganese dioxide is formed on the surface of the porous pellet. A solid electrolytic capacitor comprising a layer, a carbon layer, and a paste layer sequentially formed, wherein the anode lead wire is implanted so as to penetrate the porous pellet.