JPH04263410A - Method of adhering conductive paste for electronic part and outer electrode - Google Patents

Abstract

PURPOSE:To provide the method of adhering conductive paste generating no bubbles in the electronic part, having improved bonding strength with an outer electrode, and in the adhering paste. CONSTITUTION:In the electronic part obtained by coating an outer electrode on the terminal of a chip 3, the junction area of the outer electrode 4 is wider than the conventional electrode in which the edge face of chip is cut on the plane surface orthogonally intersecting with axis, because the edge part of the chip 3 is formed in such a manner that its cross-sectional area is gradually becoming smaller as going to outside, and the strength of bonding of the outer electrode 4 can be improved substantially. Also, as the conductive paste is stuck by conducting a process, in which the edge part of the chip C is formed in such a manner that its cross-sectional area gradually becoming smaller as going to outside direction, and another process in which the edge part of the aforesaid chip part C is picked up after it has been dipped in the conductive paste in the vessel S, the air around the adhesive surface can be pushed out to outside, and no bubbles are generated in the adhering paste.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component having an external electrode and a method for applying a conductive paste for an external electrode useful in manufacturing the electronic component.

0002

[Prior Art] Electronic components having external electrodes, such as multilayer ceramic capacitors, are manufactured by laminating a plurality of unfired sheets printed with conductive paste films that serve as internal electrodes, and then forming the laminated sheets into a prismatic shape. After cutting into shapes to obtain unfired chip parts, a conductive paste that will become external electrodes is attached to the ends of the chip parts, and the chip parts with the paste attached are fired at an appropriate temperature. It is manufactured by firing unfired ceramic and baking each paste. Some capacitors are designed so that after firing an unfired chip component, a conductive paste for external electrodes is attached and baked.

The conductive paste adhesion process in the above manufacturing process involves vertically lowering the chip component C toward a tank S containing the conductive paste P, as shown in FIGS. 12 to 14. This is done by immersing the end portion in conductive paste P to a predetermined adhesion dimension and then pulling up the chip component C. At the end of the chip component C after dipping, there is a mark shown in Figure 1.
As shown in 5, a conductive paste P is applied from the end surface to the circumferential surface.

0004

[Problems to be Solved by the Invention] However, in the conventional method of applying conductive paste by dipping, during the descent,
In particular, when the end surface Ca of the chip component C touches the surface of the conductive paste P, bubbles E are likely to be generated, and the conductive paste
The problem is that the viscosity of the paste P also affects the air bubbles E, so that the air bubbles E do not leave the end surface Ca until the immersion is completed, and the air bubbles E remain in the adhered paste P. These residual bubbles may form porous portions in the external electrodes after baking, or may impede electrical conductivity between the external electrodes and the internal electrodes.

Furthermore, since the end surface Ca of the chip component C is cut along a plane perpendicular to the axis, the bonding area with the conductive paste P cannot be further expanded, and the external electrode after baking cannot be expanded. However, there is a problem in that large bonding strength cannot be expected.

The present invention has been made in view of the above-mentioned problems, and the first purpose is to provide an electronic component with improved bonding strength of external electrodes, and the second purpose is to provide an electronic component with improved bonding strength of external electrodes.
An object of the present invention is to provide a method for applying a conductive paste without forming bubbles during paste.

[0007]

[Means for Solving the Problems] In order to achieve the above first object, in claim 1, in an electronic component formed by coating an external electrode on the end of a chip, the end of the chip is directed outward. The shape is such that the cross-sectional area gradually decreases.

[0008] In order to achieve the above second object, a second aspect of the present invention provides a step of processing the end of the chip component into a shape whose cross-sectional area gradually decreases outward, and The conductive paste is attached from the step of immersing the material in a conductive paste tank and then lifting it up.

[0009]

[Operation] In the electronic component according to claim 1, the end of the chip component has a shape in which the cross-sectional area gradually decreases toward the outside, so that the end surface of the chip component is cut on a plane perpendicular to the axis. The bonding area of the external electrode is expanded compared to the conventional one.

In the attachment method according to the second aspect, since the end of the chip component is processed into a shape whose cross-sectional area gradually decreases toward the outside, the conductive paste is applied from the apex of the end when immersed. - Since air around the edges can be pushed out by bringing the paste into contact, air bubbles are not formed in the applied paste.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross-sectional view of a multilayer ceramic capacitor to which the present invention is applied. In the drawing, the same reference numerals are used for parts having the same structure as the conventional example.

The multilayer ceramic capacitor shown in the figure includes a prismatic multilayer chip 3 formed by laminating a plurality of flat internal electrodes 1 with ceramics 2 interposed therebetween, and a multilayer chip 3 attached opposite to the multilayer chip 3. A pair of external electrodes 4 are provided.

The laminated chip 3 has spherical curved surfaces 3a formed with a predetermined curvature and bulging outward at both ends in the longitudinal direction. In addition, the internal electrodes 1 are arranged parallel to each other with their positions alternately shifted, and the edges of two of them are exposed from the curved surface 3a on the right side in the figure, and the edges of the other two are exposed from the curved surface 3a on the right side in the figure. It is exposed from the left curved surface 3a. Further, the external electrode 4 is attached to each curved surface 3a of the laminated chip 3 over the circumferential surface thereof, and is electrically connected to the edge of the internal electrode 1 exposed from each curved surface 3a.

In the above multilayer ceramic capacitor, the capacitance obtained between the internal electrodes 1 can be taken out from the pair of external electrodes 4.

The method for manufacturing the multilayer ceramic capacitor described above will be explained below.

First, a conductive paste film that will become an internal electrode is printed in a predetermined pattern on one side of an unfired sheet made of a ceramic composition and several tens of micrometers thick.

Next, several tens of printed unfired sheets are stacked and cut in the stacking direction to obtain prismatic unfired chip parts.

Next, as shown in FIG. 3, both end faces in the longitudinal direction of the unfired chip component C are polished or cut to the position of the broken line to form a spherical curved surface Cb. A metal paste film serving as an internal electrode is exposed on each curved surface Cb.

Next, as shown in FIGS. 4 to 7, the curved surface Cb
The chip component C is vertically lowered toward the tank S with the tip facing downward, and after its end is immersed in the conductive paste P to a predetermined adhesion dimension, the chip component C is pulled up. A conductive paste P is applied to the chip component C after immersion from the curved surface Cb to the circumferential surface. Conductive paste P is also applied to the other curved surface Cb of chip component C in the same manner. Although only one chip component C is shown in the drawing,
In reality, the same process is performed by arranging a large number of chip components C at the same height on a holding plate or the like and moving them up and down.

Next, the chip component C to which the paste has been applied is fired at an appropriate temperature. Through this firing, a fired ceramic body is obtained, and at the same time, each paste is fired. In the above manner, the multilayer ceramic capacitor shown in FIG. 1 is manufactured.

In the dipping process for attaching the conductive paste P, a spherical curved surface Cb is formed at the end of the chip component C in advance, so that the curved surface Cb is formed during dipping as shown in FIG.
Since the conductive paste P can be brought into contact with the conductive paste P in order starting from the apex of the curved surface and the air around the curved surface can be pushed out, air bubbles will not be formed in the adhered paste.

Furthermore, since the manufactured product is provided with an external electrode 4 so as to cover the curved surface 3a of the laminated chip 3, the end face of the laminated chip is cut on a plane perpendicular to the axis. The bonding area of the external electrodes 4 can be expanded compared to the conventional structure, and thereby the bonding strength of the external electrodes 4 can be greatly improved.

In the embodiment, a spherical curved surface Cb was formed at the end of the chip component C, but a chip component C having a quadrangular pyramidal peak Cc as shown in FIG. As shown in Figure 10, a curved surface Cd shaped like a semicircle is formed, as shown in Figure 10, a slope Ce is formed, as shown in Figure 11, a mountain part Cf of a triangular cross section is formed, etc. Various end shapes can be adopted as long as the cross-sectional area gradually decreases toward the end, and the same functions and effects as described above can be achieved. Of course, the shape of the chip component is not limited to a prismatic shape, but may also be a cylindrical shape or the like.

Furthermore, although the present invention has been applied to a multilayer ceramic capacitor in the embodiment, it goes without saying that it can be applied to other electronic components as long as they have similar external electrodes.

[0025]

As described in detail above, according to the electronic component according to claim 1, the bonding area of the external electrode can be reduced compared to the conventional device in which the end face of the laminated chip is cut along a plane perpendicular to the axis. By expanding this, the bonding strength of the external electrodes can be significantly improved.

Furthermore, according to the attachment method according to claim 2,
During immersion, the air around the adhesion surface can be pushed out to the outside, so that air bubbles are not formed in the paste being applied.

[Brief explanation of the drawing]

[Figure 1] Cross-sectional view of a multilayer ceramic capacitor

[Figure 2] Perspective view of main parts of a multilayer ceramic capacitor

[Figure 3] Manufacturing process diagram

[Figure 4] Manufacturing process diagram

[Figure 5] Manufacturing process diagram

[Figure 6] Manufacturing process diagram

[Figure 7] Manufacturing process diagram

[Fig. 8] A perspective view of a main part of a chip component showing another embodiment.

[Fig. 9] A perspective view of a main part of a chip component showing another embodiment.

[Figure 10
] A perspective view of the main parts of a chip component showing another embodiment.

[Figure 11]
A perspective view of the main parts of a chip component showing another embodiment

[Figure 12] Adhesion process diagram showing a conventional example

[Figure 13] Adhesion process diagram

[Figure 14] Adhesion process diagram

[Figure 15] Cross-sectional view of the main parts of the chip component after completion of adhesion

[Explanation of symbols]

C...chip component, Cb...curved surface, S...tank, P...conductive paper
3... Laminated chip, 3a... Curved surface, 4... External electrode.

Claims (2)

[Claims] 1. An electronic component comprising an end of a chip coated with an external electrode, characterized in that the end of the chip has a shape whose cross-sectional area gradually decreases outward. . 2. Processing the end of the chip component into a shape whose cross-sectional area gradually decreases outward, and immersing the end of the chip component in a conductive paste bath and then pulling it up. 1. A method for attaching a conductive paste for external electrodes, comprising: