JPH0661089A - Ceramic electronic parts - Google Patents

Abstract

PURPOSE:To obtain ceramic electronic parts excellent in solderbility and adhesion. CONSTITUTION:In a ceramic electronic parts having a ceramic element 2 and an outer electrode 4 thereon, the outer electrode 4 is constituted of the following; a first layer 5 formed on the ceramic element 2 the main component of which layer is metal and glass, and a second layer 6 which is formed on the first layer 5, has a silver or platinum layer on the surface and contains metal powder as the main component. In this structure, the adhesion of the outer electrode 4 to the ceramic element 2 is improved, and solderbility is also enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic electronic component, and more particularly to a ceramic electronic component suitable for application to electronic components such as chip inductors and multilayer chip capacitors.

[0002]

2. Description of the Related Art Most external electrodes of conventional ceramic electronic parts are those prepared by mixing silver or silver-palladium alloy powder with glass frit, forming a paste, and baking the mixture, and are not necessarily excellent in solderability. Therefore, in the case of chip-type electronic components that have been widely used due to miniaturization in recent years, most of them have been plated with nickel, tin or the like on the baked electrodes.

[0003]

However, in the case of such a ceramic electronic component, when the electroplating is performed, the plating solution penetrates into the ceramic body and remains inside, which sometimes causes deterioration of the characteristics of the electronic component. There was a problem of letting it.

Therefore, attempts have recently been made to use an adhesive type carbon-containing conductive paste as an external electrode, but in the case of such a conductive paste, the adhesiveness with the ceramic body is insufficient. Also, in the case of a multilayer ceramic electronic component having a large number of internal electrodes, the contactability between the internal electrodes and the external electrodes was not good, and there was a practical problem.

Therefore, the present invention is excellent in solderability,
Moreover, it is an object of the present invention to provide a ceramic electronic component having an external electrode having good adhesive strength.

[0006]

To achieve the above object, the invention according to claim 1 provides a ceramic electronic component having a ceramic body and external electrodes on the ceramic body, wherein the external electrodes are A first layer mainly composed of a metal and glass formed on the ceramic body, and a second layer mainly composed of a metal powder having a silver or platinum layer on the surface formed on the first layer, It is composed of.

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

According to a third aspect of the invention, in the first aspect of the invention, the first layer is a layer containing a metal and glass as main components, and a metal formed on this layer as a main component is glass. It has a two-layer structure with a layer not containing it.

According to a fourth aspect of the present invention, in the first to third aspects of the invention, the second layer is a layer containing a metal powder having a silver or platinum layer on the surface as a main component, and the second layer is formed on the layer. It has a two-layer structure with the formed layer of solder or tin.

[0010]

According to the ceramic electronic component of claim 1,
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 this first layer has a silver or platinum layer on the surface. Since the layer is composed mainly of metal powder, the first layer improves the adhesion to the ceramic body, and the second layer improves the solderability. Due to the division of roles, the adhesive strength with the ceramic body is good and the solderability is also excellent.

According to the ceramic electronic component of the second aspect, 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 made. Become.

According to another aspect of the ceramic electronic component of the present invention, the first layer includes a layer containing metal and glass as main components and a layer formed on the layer containing metal as main components and not containing glass. Since it has a two-layer structure, the bonding surface side of the first layer and the second layer is a layer containing no glass, and the structure of the second layer mainly composed of metal powder having a silver or platinum layer on the surface. Together, the solderability of the external electrodes becomes good.

According to another aspect of the ceramic electronic component of the present invention, the second layer of the external electrode comprises a layer mainly composed of metal powder having a silver or platinum layer on the surface, and a solder or a layer formed on this layer. Since it has a two-layer structure with a layer made of tin, the solderability becomes better.

[0014]

EXAMPLES Examples of the present invention will be described in detail below.

FIG. 1 shows a multilayer chip inductor 1 which is an example of a ceramic electronic component.

This laminated chip inductor 1 is made of Cu-Z.
The ceramic body 2 made of an n-Co ferrite material, the internal electrodes 3 made of silver or the like laminated inside the ceramic body 2, and the internal electrodes 3 formed at both ends of the ceramic body 2 It has a pair of external electrodes 4 for energization.

The external electrode 4 comprises a first layer 5 mainly composed of metal and glass formed on the outer peripheral portions of both ends of the ceramic body 2, and a silver layer formed on the outer surface of the first layer 5. And a second layer 6 whose main component is a metal powder having

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

The second layer 6 is formed by coating the outside of the first layer 5 with a conductive paste whose main component is copper powder having silver formed on the surface and baking at a low temperature.

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

Next, the method for forming the external electrode 4 will be described in more detail.

Cu-Zn- which forms the ceramic body 2.
An element body (for example, 2.0 × 1.2 × 0.9 mm) composed of a Co-based ferrite material and silver that forms the internal electrode 3 is prepared, and silver is used as the first layer 5 of the external electrode 4 on this. Powder,
A conductive paste composed of lead borosilicate glass frit and organic vehicle is applied and baked at 650 ° C. for 1 hour.

Next, as the second layer 6, a conductive paste composed of copper powder having a silver-plated surface and an organic vehicle is applied to form a second layer 50.
Bake at 0 ° C for 30 minutes.

According to the external electrode 4 of the multilayer chip inductor 1 thus formed, since the surface of the metal powder of the second layer 6 is a silver layer, the solder wettability is 0.5 at 215 ° C.
It was within seconds, and since the metal powder was copper, the solder heat resistance was 10 seconds or more at 280 ° C., and good solderability was obtained.

Further, since the metal powder of the second layer 6 is baked at a low temperature, there are many voids between the metal powders, and the solder fills the voids of the metal powder of the second layer 6 during soldering. While reaching the first layer 5, it comes into close contact with the metal components of the first layer 5. As a result, the tensile strength is 5 kg or more and the bending strength is 3
Since the thickness was not less than mm, good adhesion between the external electrode 4 and the ceramic body 2 was obtained.

As described above, according to this embodiment, the multilayer chip inductor 1 having a high practical value, which is provided with the external electrodes 4 which are excellent in solderability and have a good adhesive strength with the ceramic body 2, is provided. be able to.

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

FIG. 2 shows a multilayer chip capacitor 10 as another example of the 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 internal electrodes 13 formed at both ends of the internal electrode 13 It is provided with a pair of external electrodes 14 for energization.

The external electrode 14 is a ceramic body 12.
A first layer 15 mainly composed of metal and glass formed on the outer peripheral portions of both ends of the first layer 15 and a second layer 16 mainly composed of a metal powder having a silver layer on the surface formed on the outside of the first layer 15. It has and.

The first layer 15 is a layer 15a coated with a conductive paste containing silver powder and glass as main components, and this layer 1
Each layer 15a and 15b is formed by baking at a temperature equal to or higher than the softening point of glass, which has a two-layer structure of a layer 15b in which a conductive paste containing silver powder as a main component and not containing glass is further applied on 5a. The silver powder may be a powder containing a small amount of palladium or may be a copper powder, and the glass powder is mainly lead borosilicate glass frit, but is not limited thereto.

The second layer 16 is a layer 16 which is obtained by forming a nickel layer on the surface of copper powder, and further applying a conductive paste containing metal powder having a silver layer formed thereon as a main component and baking at a low temperature.
a and a layer 16b formed by solder dipping on the layer 16a.

The particle size of the metal powder of the second layer 16 is preferably a size convenient for use as a paste, for example, 1 to 20 μm.

Next, the method of forming the external electrode 14 will be described in more detail.

An element body composed of a barium titanate-based ceramic material forming the ceramic body 12 and palladium forming the internal electrode 3 (for example, 2.0 × 1.5 × 0.
9 mm) is prepared, and the first layer 15 of the external electrode 14 is attached to this.
A conductive paste made of silver powder, lead borosilicate-based glass frit, and organic vehicle is applied as the inner layer 15a, 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 and baked at 650 ° C. for 1 hour.

Next, a nickel layer is formed on the surface of the copper powder as the inner layer 16a of the second layer 16, and a conductive paste consisting of a metal powder having a silver layer and an organic vehicle is applied on the nickel layer, and the temperature is 600 ° C. Bake for 15 minutes.

Further, as a layer 16b outside the second layer 16, the layer 16a is fluxed and dipped in a solder bath at 230 ° C.

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

3 and 4 show an enlarged state of the external electrode 14 and an enlarged state of the layer 16a of the second layer 16. As shown in FIG.

As is apparent from FIGS. 3 and 4, the second layer 1
The voids between the metal powders in the layer 16a of No. 6 are filled with the solder of the layer 16b and partially reach the layer 15b of the first layer 15.
By directly bonding and, high adhesion strength between the two can be obtained.

Penetration of the solder as described above is due to the second layer 1
This is because the metal powder of No. 6 is a bond only on the surface due to the sintering of silver on the surface, so that the gap between the metal powders is large. It has been confirmed that the external electrode 14 configured in this way has better solderability and better adhesion than the external electrode 4 does.

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 adhesive strength.

The present invention is not limited to the above-described embodiments, but can be variously modified and implemented within the scope of the invention.

For example, as mentioned in the second embodiment, the metal powder of the second layer may be a metal powder having a plurality of metal layers as long as the surface has silver or platinum. Moreover, you may mix | blend silver powder or glass in order to strengthen the bond of the metal powder of a 2nd layer.

The present invention is applicable not only to multilayer chip inductors and multilayer chip capacitors, but also to external electrodes in other ceramic electronic components.

[0047]

According to the present invention described in detail above, the following effects can be obtained.

According to the first aspect of the present invention, a first layer mainly composed of metal and glass is formed on the ceramic body, and a silver or platinum layer is formed on the surface formed on the first layer. Since the external electrode is composed of the second layer containing the metal powder formed as the main component, it is possible to provide a ceramic electronic component having an external electrode having excellent solderability and good adhesion strength.

According to the second aspect of the present invention, by using silver, silver-palladium alloy, copper or nickel as the metal powder of the first layer, the sinterability becomes good.

According to the third aspect of the present invention, the first layer has a two-layer structure of a layer containing a metal and glass as main components, and a layer containing no metal containing glass as a main component thereon. As a result, the solderability is improved.

According to the invention described in claim 4, since the second layer is formed by a layer containing a metal powder having a silver or platinum layer formed on the surface as a main component and a layer made of solder or tin, more solder is obtained. It is possible to provide a ceramic electronic component having an external electrode having good attachability.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing a multilayer chip capacitor that is another embodiment of the present invention.

FIG. 3 is an enlarged view of external electrodes of the multilayer chip capacitor shown in FIG.

FIG. 4 is an enlarged view of a circled portion in FIG.

[Explanation of symbols]

 1 Multilayer Chip Inductor 2 Ceramic Element 4 External Electrode 5 First Layer 6 Second Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01G 1/147 A 9174-5E 4/12 361

Claims (4)

[Claims] 1. A ceramic electronic component having a ceramic element body and external electrodes on the ceramic element body, wherein the external electrode comprises a metal and glass formed on the ceramic element body as a main component. A ceramic electronic component comprising a layer and a second layer formed on the first layer and containing a metal powder having a silver or platinum layer on the surface as a main component. 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 containing a metal and glass as a main component and a layer formed on the layer containing a metal as a main component and not containing glass, or 2. The ceramic electronic component according to 2. 4. The second layer has a two-layer structure of a layer mainly composed of a metal powder having a silver or platinum layer on the surface and a layer formed of solder or tin on the layer. Item 3. A ceramic electronic component according to items 1 to 3.