Ceramic electronic component

Abstract

A ceramic electronic component (101) includes a multilayer object (1) having a first surface (1a), a pad electrode (5) provided on the first surface (1a), and a protective film (6) provided so as to extend over the periphery of the pad electrode (5) to the first surface (1a) and to surround the pad electrode (5). When a virtual plane serving as a reference for the first surface (1a) is referred to as a reference surface (7), then the periphery of the protective film (6) is depressed below the reference surface (7), and at least the central surface of a portion of the pad electrode (5) which is not covered with the protective film (6) is protrudent above the reference surface (7).

Description

Ceramic Electronic Components

[0001] The present invention relates to a ceramic electronic component.

[0002] Japanese Patent Laid-Open Publication No. 2002-231860 (Patent Document 1) describes a configuration in which a conductor land is arranged on the surface of a ceramic substrate. The conductor land includes an underlying conductor film. A glass layer is arranged so as to surround the periphery of the underlying conductor film. The glass layer is arranged so as to straddle the portion of the underlying conductor film near the periphery and the surface of the ceramic substrate. A Ni-plated layer is arranged so as to cover the underlying conductor film. An Au-plated layer is arranged so as to cover the Ni-plated layer.

[0003] According to Patent Document 1, this configuration makes it possible to prevent the edge of the underlying conductor film from being pulled and turned up even when stress is generated in the Ni plating layer.

[0004] Japanese Patent Application Laid-Open No. 2002-231860

[0005] In the above-described configuration, the conductive land protrudes from the surface of the ceramic substrate. If an impact is applied to this conductive land, a crack may occur starting from the interface between the glass layer and the ceramic substrate at the outer periphery of the glass layer. If this crack propagates, a crack may occur at the interface between the underlying conductive film and the ceramic substrate, moving inward from the outer periphery of the underlying conductive film.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a ceramic electronic component in which cracks are unlikely to occur between the pad electrode and the laminate even when an impact is applied.

[0007] To achieve the above object, a ceramic electronic component according to the present invention includes a laminate having a first surface, a pad electrode disposed on the first surface, and a protective film disposed so as to straddle an outer edge of the pad electrode and the first surface and to surround the pad electrode. When an imaginary plane serving as a reference for the first surface is taken as a reference plane, the outer edge of the protective film is recessed below the reference plane, and at least a central surface of a portion of the pad electrode not covered by the protective film is raised above the reference plane.

[0008] According to the present invention, since the outer edge of the protective film is recessed from the reference plane, the interface where cracks start is located at a position recessed from the reference plane, which makes it easier to avoid situations where an impact is applied to this interface, thereby realizing a ceramic electronic component in which cracks are less likely to occur between the pad electrode and the laminate even if an impact is applied.

[0009] Fig. 3 is a partially enlarged cross-sectional view of a ceramic electronic component according to a first embodiment of the present invention. Fig. 4 is a view in which a reference plane is added to Fig. 1. Fig. 5 is a partially enlarged cross-sectional view of a ceramic electronic component according to a second embodiment of the present invention. Fig. 6 is a view in which a reference plane is added to Fig. 3. Fig. 7 is a partially enlarged cross-sectional view of a modified example of the ceramic electronic component according to the second embodiment of the present invention. Fig. 8 is a partially enlarged cross-sectional view of a ceramic electronic component according to a third embodiment of the present invention. Fig. 9 is a partially enlarged cross-sectional view of the ceramic electronic component according to the third embodiment of the present invention.

[0010] The dimensional ratios shown in the drawings do not necessarily represent the actual ratios, and may be exaggerated for the sake of convenience. In the following description, when the concepts of up and down are mentioned, they do not necessarily mean absolute up and down, but may mean relative up and down in the illustrated position.

[0011] (Embodiment 1) A ceramic electronic component according to embodiment 1 of the present invention will be described with reference to Figures 1 and 2. The ceramic electronic component according to this embodiment is shown in Figure 1. The laminate 1 has such terminal portions. Figure 1 shows an enlarged view of one terminal portion of the laminate 1 and its vicinity. This also applies to the other figures described below.

[0012] The ceramic electronic component 101 includes a laminate 1 having a first surface 1a, a pad electrode 5 disposed on the first surface 1a, and a protective film 6 disposed across the outer edge of the pad electrode 5 and the first surface 1a, surrounding the pad electrode 5. The laminate 1 is formed by stacking multiple ceramic layers. The laminate 1 is formed, for example, by stacking multiple ceramic green sheets, compressing them, and then sintering them to form an integrated structure. Some wiring connected to the pad electrode 5 may be disposed inside the laminate 1, but the internal structure of the laminate 1 is not shown here. The first surface 1a refers to the entire so-called mounting surface of the laminate 1. In FIG. 1, the first surface 1a is the entire lower surface of the laminate 1. The first surface 1a includes a wide flat portion and a recessed portion. The geometric plane assumed at the height of the wide flat portion is the reference plane 7 shown in FIG. 2. In FIG. 2, the reference plane 7 is indicated by a dashed line. FIG. 2 is a diagram in which the reference plane 7 has been added to FIG. 1.

[0013] If a virtual plane serving as a reference for first surface 1a is referred to as reference plane 7, the outer edge of protective film 6 is recessed below reference plane 7. At least the central surface of the portion of pad electrode 5 that is not covered by protective film 6 is raised above reference plane 7. The combination of pad electrode 5 and protective film 6 is sometimes referred to as a "terminal portion." When ceramic electronic component 101 is mounted on another object, electrical connection is made through the terminal portion.

[0014] The first surface 1a includes a bottom 9, an inclined surface 8, and a flat portion 14. The ceramic electronic component 101 has a recessed bottom 9 at the outer edge of the terminal portion. The flat portion 14 is a flat portion that extends to the height of the reference plane 7. The inclined surface 8 is located between the bottom 9 and the flat portion 14. The inclined surface 8 does not have to be flat, and may be a curved surface.

[0015] The configuration shown in this embodiment can be realized by forming the pad electrode 5 on the first surface 1a, and then forming the protective film 6 so as to extend over the outer edge of the pad electrode 5 and the first surface 1a, and then pressing the first surface 1a with a plate having a slight cushioning property. By doing so, the outer edge of the protective film 6 is recessed below the reference surface 7.

[0016] In this embodiment, the outer edge of the protective film 6 is recessed below the reference plane 7, so that the portion where a crack starts, i.e., the interface between the protective film 6 and the laminate 1, is located at a position recessed below the reference plane 7. This makes it easier to avoid situations in which an impact is applied to this interface. In this way, a ceramic electronic component can be realized in which cracks are less likely to occur between the pad electrode and the laminate even if an impact is applied.

[0017] In addition, in this embodiment, the outer edge of the protective film 6 is recessed below the reference plane 7, so that the amount of protrusion of the entire terminal portion can be suppressed, which is also advantageous for reducing the height.

[0018] As shown in this embodiment, an inclined surface 8 forming part of the surface of the laminate 1 is provided on the outside of the outer edge of the protective film 6, and when viewed from a direction perpendicular to the first surface 1a, the protective film 6 and the inclined surface 8 are in contact with each other, and the inclined surface 8 preferably connects a bottom portion 9 of the first surface 1a that is recessed together with the outer edge of the protective film 6 to a flat portion 14 of the first surface 1a that is at the same height as the reference plane 7. By employing this configuration, it is possible to smoothly connect the flat portion 14 that is at the same height as the reference plane 7 and the bottom portion 9 of the recess.

[0019] 3 and 4, a ceramic electronic component according to a second embodiment of the present invention will be described. The ceramic electronic component according to the second embodiment is shown in Fig. 3. Fig. 4 is Fig. 3 with a reference plane 7 added.

[0020] The basic configuration of the ceramic electronic component 102 is the same as that described in the first embodiment, but it further includes the following configuration: In the ceramic electronic component 102, the outer edge of the pad electrode 5 is recessed below the reference surface 7.

[0021] In this embodiment, the outer edge of the pad electrode 5 is recessed below the reference plane 7, which makes it difficult for an impact to be applied to the outer edge of the pad electrode 5, which could be the starting point of a crack. Therefore, it is possible to realize a ceramic electronic component in which cracks are unlikely to occur between the pad electrode and the laminate, even if an impact is applied.

[0022] In this embodiment, the outer edge of the pad electrode 5 is recessed below the reference plane 7, so that the amount of protrusion of the entire terminal portion can be suppressed, which is further advantageous for achieving a low profile.

[0023] Note that barrel polishing may be performed on the entire laminate 1 for chamfering. When the terminal portion is located near the end of the first surface 1a, barrel polishing may result in a ceramic electronic component 103 as shown in FIG. 5 . In the ceramic electronic component 103, the chamfered portion 15 formed by barrel polishing is in contact with the inclined surface 8. The flat portion 14 does not necessarily surround the entire periphery of the inclined surface 8. When the chamfered portion 15 is present as in the ceramic electronic component 103 illustrated in FIG. 5 , the flat portion 14 may be adjacent to part of the periphery of the inclined surface 8, and the chamfered portion 15 may be adjacent to the flat portion 14 instead of the flat portion 14 in other parts.

[0024] Here, the configuration in which chamfered portion 15 formed by barrel polishing and inclined surface 8 are in contact with each other is shown based on ceramic electronic component 102 described in embodiment 2, but this is merely an example. The present invention is not limited to this, and may be configured such that chamfered portion 15 formed by barrel polishing and inclined surface 8 are in contact with each other based on ceramic electronic component 101 described in embodiment 1, for example.

[0025] Third Embodiment A ceramic electronic component according to a third embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 shows the ceramic electronic component according to the third embodiment.

[0026] The basic configuration of ceramic electronic component 104 is the same as that described in embodiment 1, but it further includes the following configuration. In ceramic electronic component 104, a flat surface 11 extends outward from a portion where the outer edge of protective film 6 is recessed below reference plane 7. Flat surface 11 is lower than reference plane 7. There is a step 12 between flat surface 11 and a flat portion 14 at the same height as reference plane 7.

[0027] In this embodiment, the same effects as those described in the first embodiment can be obtained.

[0028] Furthermore, as a modification of this embodiment, a ceramic electronic component 105 shown in Fig. 7 may be used. In the ceramic electronic component 105, a flat surface 11 also extends outward from a portion where the outer edge of the protective film 6 is recessed below the reference plane 7. The flat surface 11 is lower than the reference plane 7. An inclined surface 13 is provided between the flat surface 11 and a flat portion 14 that is at the same height as the reference plane 7. Even with this configuration, the same effects as those described in the first embodiment can be obtained.

[0029] It should be noted that a plurality of the above-described embodiments may be appropriately combined and employed. The above-described embodiments disclosed herein are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims.

[0030] REFERENCE SIGNS LIST 1 laminate, 1a first surface, 5 pad electrode, 6 protective film, 7 reference surface, 8, 13 inclined surface, 9 bottom portion, 11 flat surface, 12 step, 14 flat portion, 15 chamfered portion, 101, 102, 103, 104, 105 ceramic electronic component.

Claims

1. A ceramic electronic component comprising: a laminate having a first surface; a pad electrode arranged on the first surface; and a protective film arranged to straddle an outer edge of the pad electrode and the first surface and to surround the pad electrode, wherein, when a virtual plane serving as a reference for the first surface is taken as a reference surface, the outer edge of the protective film is recessed below the reference surface, and at least the central surface of a portion of the pad electrode not covered by the protective film is raised above the reference surface.

2. The ceramic electronic component according to claim 1, wherein an outer edge of the pad electrode is recessed below the reference surface.

3. A ceramic electronic component as described in claim 1 or 2, wherein an inclined surface forming part of the surface of the laminate is provided outside the outer edge of the protective film, and when viewed from a direction perpendicular to the first surface, the protective film and the inclined surface are in contact, and the inclined surface connects a bottom portion of the first surface that is recessed together with the outer edge of the protective film to a flat portion of the first surface that is at the height of the reference plane.

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