JP3115713B2 - Ceramic electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various ceramic electronic components such as multilayer chip inductors and multilayer chip capacitors, and more particularly to the structure of external electrodes.

[0002]

2. Description of the Related Art Many of the conventional external electrodes of ceramic electronic components are obtained by mixing glass frit with silver or silver-palladium alloy powder, forming a paste, and baking the paste. For this reason, most of the chip-type electronic components that have been used frequently with the recent miniaturization have been plated with nickel, tin, or the like on the baked electrodes.

[0003] However, in the case of such a ceramic electronic component, there has been a problem that when electroplating is performed, a plating solution infiltrates into the ceramic body and remains therein, which sometimes causes deterioration of characteristics of the electronic component. .

[0004]

For this reason, it has recently been proposed to use an adhesive type conductive paste as an external electrode. However, when such a conductive paste is used, a ceramic element is required. In the case of a laminated ceramic electronic component having an internal electrode, the adhesiveness to the body is insufficient, and the contact between the internal electrode and the external electrode is not good, which poses a practical problem.

Accordingly, an object of the present invention is to provide a ceramic electronic component having an external electrode having excellent solderability and good adhesive strength.

[0006]

According to a first aspect of the present invention, there is provided a ceramic electronic component having a ceramic body and an external electrode on the ceramic body. A first layer mainly composed of metal and glass formed on the ceramic body, and a second layer mainly composed of metal powder having a silver-copper alloy layer on the surface formed on the first layer. And a layer.

According to a second aspect of the present invention, in the first aspect, the first layer is formed of silver, a silver-palladium alloy, copper,
It was selected from nickel.

According to a third aspect of the present invention, in the first aspect of the invention, the first layer comprises a layer mainly composed of metal and glass, and a glass mainly composed of metal formed on this layer. It has a two-layer structure with a layer not containing.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the second layer includes a layer mainly composed of a metal powder having an alloy layer of silver and copper on a surface thereof, It has a two-layer structure with a solder or tin layer formed thereon.

[0010]

According to the ceramic electronic component of the first aspect,
The first layer of the external electrode formed on the ceramic body is a layer mainly composed of metal and glass, and the second layer formed on the first layer is an alloy layer of silver and copper on the surface. Since the first layer has good adhesion to the ceramic body, the second layer has good solderability, and the first layer and the second layer have good solderability. Due to the role of the two layers, the adhesive strength to the ceramic body is good and the solderability is also excellent.

According to the second aspect of the present invention, since the main component of the first layer is a metal selected from silver, a silver-palladium alloy, copper, and nickel, the sinterability of the first layer can be easily increased. Become.

According to the third aspect of the present invention, the first layer includes a layer mainly composed of metal and glass, and a layer mainly composed of metal and not containing glass formed on this layer. Because of the two-layer structure, the bonding surface of the first layer with the second layer is a layer containing no glass, and the structure of the second layer mainly composed of a metal powder having an alloy layer of silver and copper on the surface Together with this, the solderability of the external electrode is improved.

According to the fourth aspect of the present invention, the second layer of the external electrode is formed on a layer mainly composed of metal powder having an alloy layer of silver and copper on the surface, and on this layer. Since it has a two-layer structure including a layer made of solder or tin, solderability is further improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail.

FIGS. 1 and 2 show a multilayer chip inductor 1 which is an example of a ceramic electronic component.

The multilayer chip inductor 1 is made of Cu-Z
A ceramic body 2 made of an n-Co ferrite material or the like, an internal electrode 3 made of silver or the like laminated inside the ceramic body 2, and both ends of the ceramic body 2 for energizing the internal electrode 3 It is composed of a pair of external electrodes 4 formed in the portion.

As shown in FIG. 1, the external electrodes 4 are formed on both ends of a ceramic body 2 with a first layer 5 mainly composed of metal and glass, and formed outside the first layer 5. A second layer 6 composed mainly of a metal powder having an alloy layer of silver and copper on the surface.

The first layer 5 is formed by applying a conductive paste containing silver powder and glass as main components to both ends of the ceramic body 2 and baking at a temperature equal to or higher than the softening point of the glass.

The second layer 6 is coated with a conductive paste mainly composed of a metal powder having an alloy layer of silver and copper on the surface,
It is formed by baking at low temperature.

The particle size of the metal powder of the second layer 6 is desirably a size convenient for use as a paste, for example, 1 to 20 μm.

Next, a method of forming the external electrode 4 will be further described.

Cu—Zn—forming the ceramic body 2
A base (for example, 2.0 × 1.2 × 0.9 mm) composed of a Co-based ferrite material and silver forming the internal electrode 3 was prepared, and silver powder was used as the first layer 5 of the external electrode 4. ,
A conductive paste made of lead borosilicate glass frit and an organic vehicle is applied and baked at 650 ° C. for 1 hour.

Next, as the second layer 6, a conductive paste composed of silver-copper alloy powder containing 70 parts by weight of silver and 30 parts by weight of copper and an organic vehicle is applied and baked at 580 ° C. for 30 minutes.

According to the multilayer chip inductor 1 thus formed, since the surface of the metal powder of the second layer 6 is an alloy of silver and copper, the solder wettability is within 1 second at 215 ° C. 280 soldering heat resistance
It was 10 seconds or more at ℃, and good solderability was obtained.

Also, since the metal powder of the second layer 6 is baked at a low temperature, there are many gaps between the metal powders, and when soldering, the solder fills the gaps of the metal powder of the second layer 6. While reaching the first layer 5, it comes into close contact with the metal component of the first layer 5. As a result, the tensile strength was 5 kg or more and the flexural strength was 3 mm or more, and good adhesion between the external electrode 4 and the ceramic body 2 was obtained.

As described above, according to the present embodiment, it is possible to provide a multilayer chip inductor 1 having a high practical value and having an external electrode 4 having excellent solderability and good adhesion strength to the ceramic body 2. Can be.

Next, another embodiment of the present invention will be described with reference to FIGS.

FIG. 4 shows a multilayer chip capacitor 10 as another embodiment of a ceramic electronic component.

The multilayer chip capacitor 10 shown in FIG.
A ceramic body 12 made of a barium titanate-based ceramic material or the like, an internal electrode 13 made of palladium or the like laminated inside the ceramic body 12, and both ends of the ceramic body 12 for supplying electricity to the internal electrode 13 It is composed of a pair of external electrodes 14 formed in the portion.

The external electrode 14 is formed on the ceramic body 12
A first layer 15 mainly composed of metal and glass formed at both ends of the first layer 15 and a second layer mainly composed of metal powder having an alloy layer of silver and copper on the surface formed outside the first layer 15. 16.

As shown in FIG. 3, the first layer 15 has a layer 15a coated with a conductive paste mainly composed of silver powder and glass, and a glass mainly composed of silver powder further formed on this layer 15a. It is formed by baking at a temperature equal to or higher than the softening point of glass in a two-layer structure with the layer 15b coated with a conductive paste not containing.

The silver powder may be a powder containing palladium or a copper powder, and the glass is mainly borosilicate glass frit, but is not limited thereto.

The second layer 16 is formed by applying a conductive paste mainly composed of a metal powder in which a silver-copper alloy layer is formed on the surface of a copper powder on the layer 15b and baking at a low temperature.
And a layer 16b formed on the layer 16a by dipping solder.

It is desirable that the metal powder of the second layer 16 has a particle size suitable for use as a paste, for example, 1 to 20 μm.

Next, a method for forming the external electrode 14 will be further described.

A base made of barium titanate-based ceramic material forming the ceramic body 12 and palladium forming the internal electrode 13 (for example, 2.0 × 1.2 ×
0.9 mm), a silver powder, a lead borosilicate glass frit, and a layer 15a on the inner side of the first layer 15 of the external electrode 14, as shown in FIG. A conductive paste made of an organic vehicle is applied and dried.

Next, as a layer 15b outside the first layer 15, a glass-free conductive paste made of silver powder and an organic vehicle is applied on the layer 15a and baked at 650 ° C. for 1 hour.

Next, as a layer 16a inside the second layer 16, a conductive paste composed of a metal powder having a silver-copper alloy layer formed on the surface of a copper powder and an organic vehicle is applied on the layer 15b, and 580 Bake at ℃ for 30 minutes.

Further, a flux is applied to the layer 16a as a layer 16b outside the second layer 16, and the layer 16a is dipped in a solder bath at 230.degree.

In this manner, the external electrodes 14 are formed on both ends of the ceramic body 12.

FIGS. 5 and 6 show a state where the external electrode 14 is enlarged and a state where the layer 16a inside the second layer 16 is enlarged.

As apparent from FIGS. 5 and 6, the second layer 1
6 between the metal powders in the layer 16a inside the
The solder 6b fills and partially reaches the layer 15b outside the first layer 15, and the second layer 16 and the first layer 15 are directly bonded to each other to obtain high adhesion strength. .

The penetration of the solder as described above is caused by the second layer 1
This is due to the fact that the metal powder of the inner layer 16a of the layer 6 is bonded only to the surface by sintering of the silver and copper alloys on the surface, so that the gap between the metal powders is large.

It was confirmed that the thus configured external electrode 14 can obtain better solderability and better adhesion than the external electrode 4 of the first embodiment.

Therefore, according to the present embodiment, it is possible to provide a sufficiently practical multilayer chip capacitor 10 having the external electrodes 14 having excellent solderability and good adhesion strength.

The present invention is not limited to the above-described embodiment, and can be variously modified within the scope without changing the gist.

For example, as described in the second embodiment, the metal powder of the second layer may be a metal powder formed with a plurality of metal layers as long as the surface is an alloy of silver and copper.

Further, silver powder or glass may be blended in order to strengthen the bonding of the metal powder of the second layer.

The present invention is characterized in that metal powder having a silver-copper alloy layer on the surface is bonded only to the surface by sintering, but the silver-copper alloy forms a eutectic composition. As a result, the melting point is lowered, and the baking can be performed at a temperature lower than that of a conductive paste of silver alone or the like, which is economically excellent.

The present invention can be applied not only to a multilayer chip inductor and a multilayer chip capacitor but also to external electrodes of other ceramic electronic components.

[0051]

According to the first aspect of the present invention, the first layer mainly composed of metal and glass formed on the ceramic body, and the first layer formed on the first layer Since the external electrode is composed of a second layer mainly composed of a metal powder having a silver-copper alloy layer formed on the surface, the external electrode has excellent solderability and good adhesion strength to the ceramic body. A ceramic electronic component having an electrode can be provided.

According to the second aspect of the present invention, by using a metal powder of the first layer selected from silver, a silver-palladium alloy, copper and nickel, a ceramic electronic device having an external electrode with good sinterability is provided. Parts can be provided.

According to the third aspect of the present invention, the first layer has a two-layer structure of a layer mainly containing metal and glass and a layer not containing glass mainly containing metal. Thereby, a ceramic electronic component having an external electrode with good solderability can be provided.

According to the fourth aspect of the present invention, since the second layer is formed of a layer mainly composed of metal powder having a silver-copper alloy layer formed on the surface thereof, and a layer made of solder or tin.
A ceramic electronic component having an external electrode with better solderability can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a multilayer chip inductor according to an embodiment of the present invention.

FIG. 2 is a front view showing a multilayer chip inductor according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a manufacturing process of a multilayer chip capacitor according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a multilayer chip capacitor according to another embodiment of the present invention.

5 is an enlarged view of an external electrode of the multilayer chip capacitor shown in FIG.

FIG. 6 is an enlarged view of a circle shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer chip inductor 2 Ceramic body 4 External electrode 5 First layer 6 Second layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-47011 (JP, A) JP-A-64-51609 (JP, A) JP-A-4-144211 (JP, A) JP-A-1- 315903 (JP, A) JP-A-4-236412 (JP, A) JP-A-3-270004 (JP, A) JP-A-6-61089 (JP, A) JP-A-6-61088 (JP, A) JP-A-6-29144 (JP, A) JP-A-2-17829 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 17/00 H01F 27/00-27/06 H01F 41/04

Claims (4)

(57) [Claims] 1. A ceramic electronic component having a ceramic body and an external electrode on the ceramic body, wherein the external electrode is formed of a metal or glass formed on the ceramic body as a main component. A ceramic electronic component, comprising: a first layer; and a second layer mainly composed of a metal powder having an alloy layer of silver and copper on a surface formed on the first layer. 2. The ceramic electronic component according to claim 1, wherein the metal of the first layer is selected from silver, a silver-palladium alloy, copper, and nickel. 3. The first layer has a two-layer structure of a layer mainly composed of metal and glass, and a layer formed on this layer and mainly composed of metal and not containing glass. 2
The described ceramic electronic component. 4. The second layer has a two-layer structure of a layer mainly composed of a metal powder having an alloy layer of silver and copper on the surface and a layer made of solder or tin formed on this layer. The ceramic electronic component according to any one of claims 1 to 3.