KR100449627B1 - A method for manufacturing tantalum electrolytic capacitor using conductive polymer layer - Google Patents

Abstract

The present invention relates to a method of manufacturing a tantalum electrolytic capacitor using a conductive polymer layer; Its purpose is to improve the electrical properties and to prevent the short circuit between the positive and negative terminals by closely contacting the electrolyte layer to the inside of the pit formed in the dielectric film and forming a thick film when manufacturing a tantalum electrolytic capacitor using polypyrrole as an electrolyte. Of course, to provide a tantalum electrolytic capacitor that can improve the withstand voltage.

According to the present invention for achieving the above object, in the method for manufacturing a tantalum electrolytic capacitor comprising the step of providing a dielectric layer in the tantalum pellet, the conductive polymer layer is formed on the pellet provided with the dielectric layer, containing the pyrrole monomer containing the pellet Polymerizing with a solution and an oxidant solution; Impregnating the polymerized pellet into a polypyrrole-containing solution to form a polypyrrole layer on the surface of the pellet; Forming an electrically conductive layer on the pellet on which the polypyrrole electrolyte layer is formed; Technical aspect of the present invention relates to a method for manufacturing a tantalum electrolytic capacitor using a conductive polymer layer comprising a.

Description

Method for manufacturing tantalum electrolytic capacitor using conductive polymer layer {A METHOD FOR MANUFACTURING TANTALUM ELECTROLYTIC CAPACITOR USING CONDUCTIVE POLYMER LAYER}

The present invention relates to the production of tantalum electrolytic capacitors using conductive polymers, and more particularly, to a method of manufacturing tantalum capacitors using polypyrrole as an electrolyte.

In general, tantalum capacitors have a larger capacity per volume, have excellent frequency characteristics and temperature characteristics, and are increasingly used due to low leakage current, low loss, and low impedance values. Tantalum capacitors are classified into chip type (aka surface mount type), dip type (lead type) and metal case type, and their uses are mainly camcorders, mobile phones, notebook PCs, etc. It is mounted and used in the surface mount parts (SMD) set of the same civil equipment, and in the case of the deep type, it is used in the civil devices such as audio and TV, and in the case of the metal case type, which is required for high reliability such as military use.

In general, as shown in FIG. 1, a tantalum capacitor includes a tantalum pellet 10, which is a core element, and the tantalum pellet 10 includes a positive electrode terminal 20 and a negative electrode terminal 30 as shown in FIG. 2. Has a structure. The tantalum pellet 10 is a core material of the tantalum capacitor which determines the capacity of the capacitor and has a significant influence on other main characteristics. The tantalum pellet 10 is formed and sintered to a predetermined size using fine and complex forms of tantalum powder, and is about 0.7-2 μm. It is a porous body that accounts for 50-60% of micropores.

The production of a tantalum electrolytic capacitor having the above structure is largely performed in the order of (tantalum pellet production)-(chemical conversion)-(calcination)-(case assembly)-(inspection). The tantalum pellet 10 is formed by forming a dielectric layer (Ta ₂ O ₅ ) through a chemical conversion treatment, and then a cathode layer (MnO ₂ / C / Ag layer) of a capacitor is formed in the firing process. If the chemical and calcined liquids are permeated along the fine pores of the tantalum pellet in this chemical and calcining step, after a predetermined time, the treated liquid is solidified by a thermochemical reaction, and this solid replaces the electrolyte, thereby exhibiting the characteristics of the capacitor. do. Therefore, the properties of tantalum capacitors are greatly affected by the chemical conversion and firing processes, among other manufacturing process steps.

On the other hand, as a solution to the problem of manganese dioxide (MnO ₂ ) used as the electrolyte of tantalum solid electrolytic capacitors using tantalum as a dielectric, products using conductive polymers having relatively high electrical characteristics and reliability have been produced as electrolytes. Polypyrrole, one of the conductive polymers, has a tendency to be used as an electrolyte of various types of electrolytic capacitors because of its high frequency characteristics and relatively good heat resistance.

Conventional manufacturing methods for tantalum electrolytic capacitors using polypyrrole, which is a conductive polymer, have a method of directly polymerizing pyrrole to tantalum pellets on which dielectric films are formed to form a polypyrrole layer, or electropolymerization after chemical polymerization. However, it is difficult to form a thick film of a tantalum electrolytic capacitor only by the method of chemical polymerization, and to form a polypyrrole thick film by a combination of chemical polymerization and electropolymerization, it is difficult to obtain a thick film having an appropriate thickness and, above all, a complicated process. In particular, even when the electrolyte layer is formed by impregnating the polypyrrole solution from the beginning, pores of the solvent exist after drying, and since the molecular size of the polypyrrole is large, it is difficult to impregnate the inside of the pit formed in the dielectric film.

Therefore, the present invention improves the electrical properties and prevents short circuit between the positive and negative terminals by closely contacting the electrolyte layer to the inside of the pit formed in the dielectric film and forming a thick film when manufacturing a tantalum electrolytic capacitor using polypyrrole as an electrolyte. In addition, the purpose of the present invention is to provide a method for manufacturing a tantalum electrolytic capacitor which can improve the breakdown voltage.

1 is an internal structure diagram of a typical tantalum electrolytic capacitor

Figure 2 is a front view of the pellet for tantalum electrolytic capacitor of Figure 1

Figure 3 is a structure diagram of the surface layer of the pellet for tantalum electrolytic capacitor of the present invention

Explanation of symbols on the main parts of the drawings

10 ...... Tantalum Pellets 12 ....... Dielectric Layer

14 ...... Polypyrrole Electrolyte Layer 15 ....... Conductive Layer

In the present invention for achieving the above object, in the manufacturing method of the tantalum electrolytic capacitor comprising the formation of a conductive polymer layer on the pellet provided with a dielectric layer, the dielectric layer is provided in the pellet,

Polymerizing the pellet provided with the dielectric layer using a pyrrole monomer-containing solution and an oxidant solution;

Impregnating the polymerized pellet into a polypyrrole-containing solution to form a polypyrrole layer on the surface of the pellet;

Forming an electrically conductive layer on the pellet on which the polypyrrole electrolyte layer is formed; It relates to a method of manufacturing a tantalum electrolytic capacitor using a conductive polymer layer comprising a.

Hereinafter, the present invention will be described in detail.

In the polypyrrole solution constituting the electrolyte layer of the tantalum electrolytic capacitor, an oxidizing agent is added dropwise to a solution in which a 5-ring heterocyclic pyrrole monomer and a dopant are dissolved, and a conductive solution in which the polymerized polypyrrole is dissolved in chloroform or metacresol is used. In order to form the polypyrrole electrolyte layer on the surface of the tantalum electrolytic capacitor, the polypyrrole solution is formed by directly impregnating the polypyrrole solution, chemically polymerizing the dielectric, or electropolymerizing after the chemical polymerization. It is difficult to penetrate the polypyrrole to the inside of the pit formed in the dielectric film, to form internal pores or to decrease the adhesion between the dielectric layer and the electrolyte layer and to form a thick film.

In order to solve this drawback, the present invention, in using the polypyrrole solution, first impregnates the tantalum pellet having the dielectric layer in the solution containing the pyrrole monomer to prepare the polypyrrole electrolyte layer completely up to the inside of the tantalum pellet coating so that there are no internal pores. It is characterized by forming a thick film using a polypyrrole solution thereon.

Figure 3 shows the surface structure of tantalum pellets prepared according to the present invention. In the pellet 10 of the present invention, as shown in FIG. 3, a dielectric layer (Ta ₂ O ₅ ) 12 is formed on the surface of the tantalum pellet through chemical conversion, and a polypyrrole electrolyte layer 14 is formed thereon. At this time, the electrolyte layer 14 formed in the tantalum pellet element of the present invention is impregnated with a tantalum pellet element having a dielectric layer in a solution containing a pyrrole monomer, and polymerized by using an oxidizing agent to prepare a polypyrrole electrolyte layer 14a Next, a pellet element on which the polypyrrole electrolyte layer 14a is formed is deposited in a polypyrrole solution to form the polypyrrole electrolyte layer 14b again. The polypyrrole electrolyte layer is appropriate to have a thickness of 5 ~ 100㎛ range.

In the polymerization treatment, the pellets provided with the dielectric layer are impregnated with a pyrrole monomer-containing solution, and then taken out, and then impregnated with the oxidant solution. In the reverse order, the pellet provided with the dielectric layer may be impregnated with the oxidant solution, and then taken out, and may be impregnated again with the pyrrole monomer-containing solution or sprayed with the pyrrole monomer-containing solution on the surface of the taken out pellet.

In forming the polypyrrole electrolyte layer 14, the pyrrole monomer solution is impregnated with a tantalum element to form a polypyrrole electrolyte layer 14a up to a dense pit between the dielectric surface layers of the tantalum pellet and the polypyrrole solution thereon. By forming the electrolyte layer (14a) using the excellent affinity and adhesion, it is possible to form a thick film.

The polypyrrole solution is not only conventional dodecylbenzenesulfonic acid but also butylbenzenesulfonic acid (butylbenzenesulfonic acid) or octylbenzenesulfonic acid (octylbenzenesulfonic acid), n≥4 or more alkylbenzenesulfonic acid (alkylbenzenesulfonic acid; C _n H _{2n + 1} C ₆ H A polypyrrole solution having ₄ SO ₃ H) as a dopant can be used. The pyrrole monomer-containing solution may use a stock solution or a diluent thereof, and more preferably dilute the concentration to at least 20% when the diluent is used.

In the present invention, the oxidizing agent used in the polypyrrole polymerization may be ammonium persulfate (NH ₄ ) ₂ S ₂ O ₈ ], ferric chloride (FeCl ₃ ), potassium permanganate (KMnO ₄ ), dichromate ( K ₂ Cr ₂ O ₇ ), potassium iodide (KIO ₃ ), potassium perchlorate (KClO ₄ ) or potassium chlorate (KClO ₃ ) can be applied.

Thereafter, an electrically conductive layer 15 is formed on the tantalum pellet element 10 provided with the polypyrrole electrolyte layers 14a and 14b, as shown in FIG. The electrically conductive layer may be formed using a paste composed of carbon or metal powder or mixed powder. Preferably, the carbon layer is prepared by impregnating the carbon-containing solution, and then containing the silver pellet containing the carbon layer. The solution is impregnated to finally form an Ag layer.

Hereinafter, the present invention will be described in detail through examples.

EXAMPLE

Conventional Example 1

The polypyrrole electrolyte layer was chemically polymerized and formed on a tantalum pellet device having a Ta ₂ O ₅ dielectric layer formed by chemical conversion, and then a carbon layer and an Ag layer were formed.

Conventional Example 2

A tantalum pellet element having a Ta ₂ O ₅ dielectric layer formed by chemical treatment was deposited on a polypyrrole solution to form a polypyrrole electrolyte layer, and then a carbon layer and an Ag layer were formed.

Inventive Example

The same tantalum pellet element was first impregnated into the pyrrole monomer, and then polymerized with a 20% FeCl ₃ solution as an oxidizing agent. Subsequently, the tantalum element was deposited in a polypyrrole solution to form a polypyrrole electrolyte layer having a thickness of about 50 μm, and then a carbon layer and an Ag layer were prepared. In this case, the polypyrrole solution used was polymerized by mixing a pyrrole monomer: dodecylbenzenesulfonic acid: ammonium persulfate in a molar ratio of 1: 0.5: 0.13 and then liquefied using a chloroform solution.

As such, the electrical properties of the manufactured tantalum capacitors were measured at two kinds of frequencies, and the results are shown in Table 1.

division Measuring frequency Capacity value (㎌) Impedance Withstand voltage (10V) Invention 120 Hz 110.611 11.5767 pass 10KHz 101.108 0.1546 Conventional Materials 1 120 Hz 100.12 10.78 fail 10KHz 92.411 0.1417 Conventional material 2 120 Hz 101.174 13.118 pass 10KHz 91.135 0.22

As shown in Table 1, when the tantalum electrolytic capacitor of the same capacity is manufactured, it was found that the one manufactured according to the present invention is superior in capacitance, impedance, and withstand voltage than the conventional one.

As described above, the present invention closely forms a polypyrrole electrolyte layer to the inside of the pit formed in the dielectric film of the tantalum element, and forms an electrolyte layer using a polypyrrole solution thereon to form a thick film having excellent affinity and adhesion. It is very useful to provide a tantalum electrolytic capacitor with improved electrical characteristics.

Claims (8)

In the method of manufacturing a tantalum electrolytic capacitor comprising the step of providing a dielectric layer on the tantalum pellet, and then forming a conductive polymer layer on the pellet provided with the dielectric layer, Impregnating the pellet having the dielectric layer in a solution containing a pyrrole monomer and polymerizing the solution using an oxidant solution; Impregnating the polymerized pellet into a polypyrrole-containing solution to form a polypyrrole layer on the surface of the pellet; Forming an electrically conductive layer on the pellet on which the polypyrrole electrolyte layer is formed; Method for manufacturing a tantalum electrolytic capacitor using a conductive polymer layer, characterized in that comprises a The method according to claim 1, wherein the pyrrole monomer-containing solution is prepared using a stock solution or a dilution thereof. The method of claim 2, wherein the pyrrole monomer-containing solution is prepared using a solution diluted to at least 20% of its concentration. The method of claim 1, wherein the oxidizing agent is ammonium persulfate (NH ₄ ) ₂ S ₂ O ₈ ], ferric chloride (FeCl ₃ ), potassium permanganate (KMnO ₄ ), dichromate (K ₂ Cr ₂ O ₇ ), potassium iodide (KIO ₃ ), potassium perchlorate (KClO ₄ ) or potassium chlorate (KClO ₃ ) The production method characterized in that one selected from The method of claim 1, wherein the polypyrrole electrolyte layer has a thickness in a range of 5 to 100 μm. The method according to claim 1, wherein the polymerization process is performed by impregnating a pellet having a dielectric layer impregnated with a pyrrole monomer-containing solution and then taking it out, followed by impregnation with an oxidant solution. The method according to claim 1, wherein the polymerization process is performed by impregnating a pellet having a dielectric layer in a solution containing a pyrrole monomer and then spraying an oxidizing agent solution on the surface of the pellet taken out. The method of claim 1, wherein the electrically conductive layer is formed using a paste made of carbon, metal powder or mixed powder.