JPH1074661A - Manufacture of electronic part and conductive paste used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure preferable electrically connection between an inner electrode and an outer electrode by applying, a conductive past containing boric acid as the outer electrode to the surface where the inner electrode of an electronic part is exposed, and drying and baking are effected. SOLUTION: A conductive paste containing boric acid is applied to the face where an inner electrode 1 is exposed, and the electronic part is baked. As boric acid in the conductive paste, fine powder of boric acid is added or an aqueous solution is added. The conductive paste used for an electronic part contains metal powder particles, an aqueous solution, and boric acid. As metal powder particles, at least one kind selected from a group of Cu, Ag, Ni, Pd, and Zn is used. Consequently, oxidization of the electrode metal which becomes a cause of defective connection between the inner electrode 1 and an outer electrode 2 is prevented, so that preferable electrical connection can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electronic component having a structure in which an internal electrode and an external electrode are electrically connected by metal bonding, and a conductive paste used for the method. This is to ensure a good connection.

[0002]

2. Description of the Related Art A conventional example using a multilayer ceramic capacitor as an electronic component having an internal electrode and an external electrode will be described. FIG. 2 is a sectional view of a conventional multilayer ceramic capacitor. The multilayer ceramic capacitor has internal electrodes 21 formed therein, and each end of the internal electrode 21 is formed to be exposed at a specific end face of the multilayer ceramic capacitor. A conductive paste for forming the external electrode 22 is applied to the exposed end face so as to be electrically connected to the internal electrode 21, dried, and then baked, so that each metal is formed between the conductive paste and the internal electrode 21. Are alloyed to form a metal bond and are electrically connected.

[0003]

However, in a multilayer ceramic capacitor, when a base metal such as nickel is used for the internal electrode 21 and copper is used for the external electrode 22, both the nickel of the internal electrode 21 and the copper of the external electrode 22 are oxidized. It is easy to apply the conductive paste for the external electrode 22
Oxidation easily occurs in each of the steps of drying and firing, and as a result, there has been a problem that metal bonding between the internal electrode 21 and the external electrode 22 due to alloying is hindered and a connection failure occurs.

An object of the present invention is to provide a method for manufacturing an electronic component which solves the above-mentioned conventional problems and a conductive paste used for the method.

[0005]

In order to achieve the above object, the present invention provides a method for applying, drying and baking a conductive paste containing boric acid as an external electrode on a surface of an electronic component where an internal electrode is exposed. is there. This is because boric acid is an internal electrode,
The purpose of the present invention is to prevent oxidation of an electrode metal that inhibits metal bonding between an external electrode and promote good metal bonding between an internal electrode and an external electrode.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The invention according to claim 1 of the present invention relates to an electronic component having an internal electrode, in which a conductive paste containing boric acid is applied to a surface where the internal electrode is exposed, and then the electronic component is formed. It is baked in. This is because the added boric acid melts at a temperature of about 185 ° C. during the baking process of the electrode, oozes out onto the surface of the applied conductive paste, covers the entire coated surface with a thin film, and removes the metal in the conductive paste and the electron Prevents oxidation of the internal electrode surface of the component, and further heating the boric acid melted at around 300 ° C becomes boric anhydride, preventing oxidation of the electrode metal and melting the oxide film on the internal electrode and external electrode metal surfaces, It also has the function of removing. Therefore, when the temperature is further increased, the respective metals diffuse from each other from the contact surface between the applied metal of the external electrode and the metal of the internal electrode, and at a predetermined baking temperature, alloy at the contact surface of these metals to form an alloy. The electrode and the external electrode are metal-bonded, so that good electrical connection can be ensured.

According to a second aspect of the present invention, boric acid in the conductive paste is added as fine boric acid powder. Even when boric acid is added in the form of fine powder, the same effect as described above can be obtained.

According to a third aspect of the present invention, boric acid in a conductive paste is added as a boric acid solution. The same effect as described above can be obtained even when added in the state of a boric acid solution.

According to a fourth aspect of the present invention, after the conductive paste is applied to the electronic component body, the conductive paste is dried, and then the conductive paste is baked. The added boric acid prevents oxidation of the electrode metal at the temperature of the baking process of the conductive paste for external electrodes,
The formed metal oxide film is dissolved and removed to promote metal bonding at the contact surface between the internal electrode and the external electrode.

The invention according to claim 5 of the present invention is a conductive paste used for an electronic component containing metal powder particles, a solvent and boric acid. This is because, in an electronic component having an internal electrode, the conductive paste is applied as an external electrode so as to be connected to the internal electrode, dried, and then baked, so that boric acid contained therein prevents oxidation of each metal. This is an effective conductive paste capable of dissolving and removing an oxide film on a metal surface and performing good metal bonding between an internal electrode and an external electrode.

According to a sixth aspect of the present invention, there is provided an electroconductive device according to the fifth aspect, wherein the metal powder particles are at least one selected from the group consisting of Cu, Ag, Ni, Pd and Zn. Paste. This is that boric acid contained in the conductive paste effectively acts on the metal group and can form a good metal bond between the internal electrode and the external electrode. The effect is as already explained.

The invention according to claim 7 of the present invention is the conductive paste used for the electronic component according to claim 5 or 6, wherein boric acid is added as fine boric acid to the conductive paste. This means that even when boric acid is added and contained in the form of fine powder, it effectively prevents oxidation of the electrode metal and removes the oxide film on the metal surface. As you did.

According to the invention of claim 8 of the present invention, a boric acid solution is added as boric acid to the conductive paste.
Or a conductive paste used for the electronic component according to 6. This effectively prevents the oxidation of the electrode metal and removes the oxide film on the metal surface even when boric acid is added and contained in the state of a solution. It is on the street.

(Embodiment 1) Hereinafter, an embodiment of the present invention will be described with reference to an F characteristic (−20% to + 80%) of a capacitance of 100 nF.
%) A description will be given using a conductive paste in which boric acid is added to a multilayer ceramic capacitor.

In the monolithic ceramic capacitor having the structure shown in FIG. 1, boric acid is not added to both end surfaces of the internal electrode 1 made of nickel, which is exposed, for the external electrode 2 made of copper. A conductive paste and a conductive paste to which 5 wt% of boric acid is added in the form of fine powder are applied, dried at a temperature of 120 ° C. for 5 minutes, and baked at a temperature of 900 ° C. for 10 minutes to obtain a laminated ceramic. A capacitor was obtained. The capacitance of the obtained multilayer ceramic capacitor was measured, and then 50 capacitors having a capacitance within the allowable range (80 nF to 180 nF) and 50 capacitors having a capacitance outside the allowable range (<80 nF) were measured with respect to the internal electrode 1. After polishing the orthogonal side surfaces, the connection state between the internal electrode 1 and the external electrode 2 was observed with a microscope, and the results are shown in (Table 1). In the case of the connection failure, a sample in which one or more places where the internal electrode 1 and the external electrode 2 were not connected was counted as a connection failure.

[0016]

[Table 1]

As can be seen from Table 1, in the case where boric acid was not added, 0.8% of defects out of the allowable range of capacitance occurred, whereas 5 wt% of boric acid was added. No capacitance failure occurred from the device. In addition, when the side surface was polished, it was recognized that at least one portion where the internal electrode 1 and the external electrode 2 were not connected occurred in all of the products having poor capacitance. On the other hand, even when the capacitance was within the allowable range, when the boric acid was not added, the connection was not completely separated but the connection state was unstable. The metal of the internal electrode 1 and the metal of the external electrode 2 were completely alloyed, and no unstable metal was found.

From the above results, the use of the conductive paste to which boric acid is added as the external electrode 2 prevents oxidation of the electrode metal, which may cause a connection failure between the internal electrode 1 and the external electrode 2, and It can be seen that an oxide film generated on the surface of the electrode metal is also removed to enable metal bonding between the internal electrode 1 and the external electrode 2, and that good electrical connection can be obtained.

Although the present embodiment has been described using a multilayer ceramic capacitor, the present invention is not limited to a multilayer ceramic capacitor, but may be applied to an electronic component having a configuration in which the internal electrode 1 and the external electrode 2 need to be electrically connected. If so, it can be applied to any electronic component.

[0020]

As described above, according to the present invention, when a conductive paste to which boric acid is added is used for an external electrode of an electronic component, even when a base metal is used, a good electric connection between the internal electrode and the external electrode can be obtained. Connection can be secured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional multilayer ceramic capacitor.

[Explanation of symbols]

 1 internal electrode 2 external electrode 21 internal electrode 22 external electrode

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Satoshi Endo 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Yoshiya Sakaguchi 1006 Kadoma Kadoma, Kadoma City, Osaka Pref.

Claims (8)

[Claims] 1. A method of manufacturing an electronic component having an internal electrode, wherein a conductive paste containing boric acid is applied to an end face where the internal electrode is exposed, dried, and baked on the electronic component. 2. The method according to claim 1, wherein the conductive paste containing boric acid as a fine boric acid powder is baked on the end face of the electronic component.
3. The method for manufacturing an electronic component according to claim 1. 3. The method for manufacturing an electronic component according to claim 1, wherein a conductive paste to which boric acid is added as a boric acid solution is baked on an end face of the electronic component. 4. The method according to claim 1, wherein the conductive paste is applied to the electronic component, dried, and then the conductive paste is baked.
The method for manufacturing an electronic component according to any one of the above. 5. A conductive paste used for an electronic component containing metal powder particles, a solvent and boric acid. 6. The metal powder particles of Cu, Ag, Ni, P
The conductive paste used for an electronic component according to claim 5, comprising at least one selected from the group consisting of d and Zn. 7. The conductive paste according to claim 5, wherein a fine powder of boric acid is added to the conductive paste as boric acid. 8. The conductive paste used for an electronic component according to claim 5, wherein a boric acid solution is added as boric acid to the conductive paste.