CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2020-081566 filed on May 1, 2020. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a ceramic electronic component including a ceramic body and an external electrode on a surface of the ceramic body, and to a method for manufacturing a ceramic electronic component suitable to manufacture the ceramic electronic component of the present invention.

2. Description of the Related Art

When a ceramic electronic component including a ceramic body and an external electrode on a surface of the ceramic body is soldered to and thus mounted on a substrate, and the substrate is warped, flexed or the like, the ceramic body may have a cracked side surface. That is, in mounting by soldering, a land electrode of the substrate and the external electrode of the ceramic electronic component are firmly soldered together, and when the substrate is warped, flexed or the like and stress is caused, the stress is not released anywhere, and instead is transmitted to the ceramic body, and the ceramic body may have a side surface cracked.

To address this issue, a ceramic electronic component is disclosed in Japanese Patent Laid-Open No. 2005-217128. In Japanese Patent Laid-Open No. 2005-217128, it is assumed that a ceramic body cracks due to glass added to an external electrode in order to improve bonding strength, and a large amount of glass is diffused in a region of the ceramic body where the external electrode is provided, whereas no glass is diffused in a region of the ceramic body where the external electrode is not provided. Therefore, the ceramic body has a difference in stress at a boundary between the region with the external electrode and the region without the external electrode, and the boundary is thus more likely to crack.

More specifically, when a ceramic electronic component including a pair of external electrodes is cut and observed in a cross section including the pair of external electrodes, the external electrode typically has a U shape and includes an end surface region on an end surface of the ceramic body and a side surface region on a side surface of the ceramic body. When the external electrode has glass added thereto, a region in which a large amount of glass is diffused and a region in which glass is not diffused are formed in the ceramic body at a terminal portion of the side surface region of the external electrode. Therefore, a difference in stress is caused at a boundary between the region where the large amount of glass is diffused and the region where glass is not diffused, and the boundary is thus more likely to crack. Note that in Japanese Patent Laid-Open No. 2005-217128, the side surface of the ceramic body provided with the side surface region of the external electrode is referred to as a “major surface.”

Accordingly, in the ceramic electronic component of Japanese Patent Laid-Open No. 2005-217128, the external electrode includes the end surface region formed of a layer having a high glass content, and the side surface region formed of two layers of a lower layer having a low glass content and an upper layer formed on the lower layer and having a high glass content. That is, a layer having a high glass content is not directly formed on the side surface of the ceramic body, and instead, initially, a lower layer having a low glass content is formed, and an upper layer having a high glass content is formed thereon, so that the ceramic body does not have a side surface including a region with glass diffused therein, and the side surface of the ceramic body is unlikely to be cracked even when a substrate having the ceramic electronic component mounted thereon is warped, flexed or the like. That is, the boundary between the region with a large amount of glass diffused therein and the region with no glass diffused therein is not located in the side surface of the ceramic body, so that the side surface of the ceramic body is unlikely to be cracked even when the substrate having the ceramic electronic component mounted thereon is warped, flexed or the like.

The ceramic electronic component of Japanese Patent Laid-Open No. 2005-217128 includes an external electrode having a side surface region entirely formed of two layers including a lower layer having a low glass content and an upper layer having a high glass content, and thus has a surface with the high glass content layer exposed. Furthermore, although the external electrode typically has a surface electrolytically plated to provide a plating layer formed thereon, the external electrode, having the surface with the high glass content layer exposed, prevents the plating layer from being formed on the glassy portion. The portion that does not have the plating layer formed thereon would have low solder wettability.

SUMMARY OF THE INVENTION

A ceramic electronic component according to a preferred embodiment of the present invention includes a ceramic body including a ceramic layer and an internal electrode stacked in layers, and at least a pair of external electrodes on a surface of the ceramic body. The internal electrode and the external electrode are electrically interconnected. The ceramic body includes a pair of end surfaces at which the internal electrode is led out, and four side surfaces connecting the pair of end surfaces. The external electrode includes at least a high glass content layer including glass and a low glass content layer including no glass or including glass at a ratio smaller than the high glass content layer. In at least one of a cross section including the pair of external electrodes that is obtained by cutting in a direction perpendicular or substantially perpendicular to a direction of a plane in which the internal electrode extends and a cross section including the pair of external electrodes that is obtained by cutting in a direction parallel or substantially parallel to the direction of the plane in which the internal electrode extends, the external electrode includes an end surface region on the end surface and a side surface region on the side surface. The side surface region includes a first end portion electrically connected to the end surface region at a ridge portion of the ceramic body connecting the end surface and the side surface together, and a second end portion opposite to the first end portion. The end surface region includes the high glass content layer in contact with the ceramic body. At least at a portion where the internal electrode is led out, at least the second end portion and a vicinity thereof includes the low glass content layer in contact with the ceramic body. At least a portion of the side surface region including a surface with the low glass content layer exposed.

A method for manufacturing a ceramic electronic component according to a preferred embodiment of the present invention including a ceramic body including a ceramic layer and an internal electrode stacked in layers, and at least a pair of external electrodes on a surface of the ceramic body, wherein the internal electrode and the external electrode are electrically interconnected, the ceramic body includes a pair of end surfaces at which the internal electrode is led out, and four side surfaces connecting the pair of end surfaces, the external electrode includes at least a high glass content layer including glass and a low glass content layer including no glass or including glass at a ratio smaller than the high glass content layer, in at least one of a cross section including the pair of external electrodes that is obtained by cutting in a direction perpendicular or substantially perpendicular to a direction of a plane in which the internal electrode extends and a cross section including the pair of external electrodes that is obtained by cutting in a direction parallel to the direction of the plane in which the internal electrode extends, the external electrode includes an end surface region on the end surface and a side surface region on the side surface, the side surface region includes a first end portion electrically connected to the end surface region at a ridge portion of the ceramic body connecting the end surface and the side surface together, and a second end portion opposite to the first end portion, the end surface region includes the high glass content layer in contact with the ceramic body, at least at a portion where the internal electrode is led out, and at least the second end portion and a vicinity thereof includes the low glass content layer in contact with the ceramic body, the method including preparing a plurality of ceramic green sheets; applying a first conductive paste to a major surface of at least one ceramic green sheet; stacking a plurality of ceramic green sheets in layers to prepare a green ceramic body; firing the green ceramic body to prepare a ceramic body including the ceramic layer and the internal electrode stacked in layers; and applying second and third conductive pastes to a surface of the fired ceramic body and baking the second and third conductive pastes on the surface of the ceramic body to form the external electrode.

Ceramic electronic components according to preferred embodiments of the present invention each include an external electrode including a side surface region with at least a portion thereof including a surface with a low glass content layer exposed, and at that portion, the external electrode includes the side surface region with higher platability or larger plating strength and, thus, higher solder wettability than a high glass content layer.

Further, methods for manufacturing ceramic electronic components according to preferred embodiments of the present invention each facilitate manufacturing ceramic electronic components according to preferred embodiments of the present invention.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

