Multilayer ceramic electronic component and its manufacturing method

Abstract

A laminated ceramic electronic component includes a body component, a first external electrode, a second external electrode, and a protective layer. The body component is formed by alternatingly laminating a ceramic layer and an internal electrode layer, and has a first surface, a second surface, a first end surface, a second end surface, a first side surface, and a second side surface. The internal electrode layer is exposed on the first side surface and the second side surface, and on the first end surface or the second end surface. The first external electrode and the second external electrode extend from the first end surface or the second end surface to at least one of the first surface and the second surface, and have a first external electrode side surface and a second external electrode side surface. The protective layer contains a ceramic material and covers the first side surface, the second side surface, and the first external electrode side surface and the second external electrode side surface of the first external electrode and the second external electrode.

Description

[Technical field]

[0001] The present disclosure relates to a multilayer ceramic electronic component and a method for manufacturing the same. [Background technology]

[0002] An example of the prior art is described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-118083 A Summary of the Invention

[0004] The multilayer ceramic electronic component of the present disclosure includes a substantially rectangular parallelepiped element component, a first external electrode, a second external electrode, and a protective layer. The element component is formed by alternately stacking a plurality of ceramic layers and a plurality of internal electrode layers having different polarities, and has a first surface and a second surface facing each other in a stacking direction of the plurality of ceramic layers and the plurality of internal electrode layers, a first end surface and a second end surface facing each other, and a first side surface and a second side surface facing each other. The plurality of internal electrode layers are exposed to the first side surface and the second side surface, and are exposed to either the first end surface or the second end surface according to polarity. The first external electrode is connected to the internal electrode layer exposed to the first end surface, and the second external electrode is connected to the internal electrode layer exposed to the second end surface. Each of the first external electrode and the second external electrode extends over at least one of the first surface and the second surface, and has a first external electrode side surface and a second external electrode side surface that are flush with the first side surface and the second side surface, respectively. The protective layer includes a ceramic material and covers the first side surface and the second side surface and the first external electrode side surface and the second external electrode side surface of the first external electrode and the second external electrode.

[0005] In addition, a method for manufacturing a multilayer ceramic electronic component disclosed herein includes cutting a master laminate formed by alternately stacking a plurality of ceramic green sheets and a plurality of internal electrode layers at predetermined intervals to produce a first rod-shaped body having first and second surfaces and first and second cut surfaces, chamfering edges between the first and second surfaces and the first and second cut surfaces, and forming first and second external electrodes extending from each of the first and second cut surfaces to at least one of the first and second surfaces to produce a second rod-shaped body, cutting the second rod-shaped body at predetermined intervals in a direction perpendicular to a longitudinal direction of the second rod-shaped body to form third and fourth cut surfaces at which the plurality of internal electrode layers are exposed, and forming a protective layer containing a ceramic material on each of the third and fourth cut surfaces. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view illustrating an example of a multilayer ceramic electronic component according to an embodiment of the present disclosure. [Diagram 2] 2 is an exploded perspective view showing the multilayer ceramic electronic component of FIG. 1. [Diagram 3] 3 is a cross-sectional view showing a body part of the multilayer ceramic electronic component taken along the cutting line AA in FIG. 2. [Figure 4] 3 is a photograph showing a part of the multilayer ceramic electronic component cut along the cutting line AA in FIG. 2. [Figure 5A] FIG. 1 is a perspective view showing a state in which a plurality of conventional multilayer ceramic electronic components are mounted on a mounting substrate. [Figure 5B] 2 is a perspective view showing a state in which a plurality of the multilayer ceramic electronic components of FIG. 1 are mounted on a mounting substrate. [Figure 6A] FIG. 5B is a cross-sectional view taken along the cutting line BB in FIG. 5A. [Figure 6B] FIG. 5C is a cross-sectional view taken along the cutting line CC in FIG. 5B. [Figure 7] FIG. 4 is a perspective view showing an example of a multilayer ceramic electronic component according to another embodiment of the present disclosure. [Figure 8]8 is an exploded perspective view showing the multilayer ceramic electronic component of FIG. 7. [Figure 9] FIG. 11 is a perspective view showing an example of a multilayer ceramic electronic component according to still another embodiment of the present disclosure. [Figure 10] 10 is a cross-sectional view taken along the cutting line DD in FIG. 9. [Figure 11] FIG. 2 is a perspective view showing a state in which a conductive paste is printed on a ceramic green sheet. [Figure 12] FIG. 2 is an external view showing a state in which a plurality of ceramic green sheets on which a conductive paste is printed are stacked. [Figure 13] FIG. 2 is a perspective view showing a base laminate. [Figure 14] FIG. 2 is a perspective view showing a state in which a first rod-shaped body obtained by cutting the base laminate has been chamfered. [Figure 15] 11 is a perspective view showing a state in which a plurality of first rod-shaped bodies are rotated so that a first cut surface is positioned within an imaginary plane. FIG. [Figure 16] 13 is a diagram showing a state in which external electrode paste is applied to a first cut surface of a first rod-shaped body. FIG. [Figure 17] FIG. 11 is a perspective view showing a second rod-shaped body on which an external electrode base layer is formed. [Figure 18] FIG. 11 is a perspective view showing a state in which a second rod-shaped body is being cut. [Figure 19] FIG. 2 is a perspective view showing a state in which the cut surfaces of second base parts cut into individual chips are aligned in the up-down direction. [Figure 20] FIG. 4 is a cross-sectional view illustrating a state in which ceramic paste is being applied to a second base part. [Figure 21] FIG. 4 is a perspective view showing a state of a second base part on which a protective layer has been formed. [Figure 22A] FIG. 4 is a cross-sectional view that illustrates a state in which a plurality of second rod-shaped bodies are melt-fixed to one another by a thermoplastic resin sheet to produce an assembly. [Figure 22B] FIG. 4 is a cross-sectional view that illustrates a state in which a plurality of second rod-shaped bodies are melt-fixed to one another by a thermoplastic resin sheet to produce an assembly. [Diagram 23]FIG. 13 is a perspective view showing a state in which the assembly is cut to produce a third rod-shaped body. [Figure 24] 11 is a perspective view showing a state in which a ceramic green sheet is arranged on a cut surface of a third rod-shaped body. FIG. [Diagram 25] FIG. 11 is a perspective view showing a third rod-shaped body to which a ceramic green sheet is attached. [Figure 26] FIG. 11 is a perspective view showing a state of a third rod-shaped body to which a ceramic green sheet has been attached after firing. [Figure 27] FIG. 2 is a perspective view showing a base laminate laminated on a support sheet. [Figure 28] FIG. 2 is a perspective view showing a state in which a first rod-shaped body obtained by cutting the base laminate together with the support sheet has been chamfered. [Figure 29] 29 is a perspective view showing a state in which the first rod-shaped body of FIG. 28 is rotated so that the cut surface is positioned in the up-down direction. [Diagram 30] 30 is a cross-sectional view showing a state in which an external electrode foundation layer is applied to a cut surface of the first rod-shaped body in FIG. 29. FIG. [Diagram 31] 31 is a perspective view showing a second rod-shaped body in which an external electrode base layer is formed on the first rod-shaped body in FIG. 30. FIG. [Diagram 32] 32 is a perspective view showing a state in which the support sheet of the second rod-shaped body in FIG. 31 has been peeled off. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The objects, features and advantages of the present disclosure will become more apparent from the following detailed description and drawings.

[0008] 2. Description of the Related Art In recent years, electronic components mounted on circuit boards of electronic devices have become more highly functional and more densely mounted on the circuit boards. One example of such electronic components is a multilayer ceramic electronic component, particularly a multilayer ceramic capacitor.

[0009] Patent Document 1 discloses that in order to improve the obtainable capacitance per unit volume, which is the function of a multilayer ceramic capacitor, the side margin portions for protecting the internal electrodes are made thin to increase the area ratio of the internal electrodes, and by not forming external electrodes on the side surfaces of the element body that constitutes the multilayer ceramic capacitor, the occurrence of leakage current between the external electrodes and the internal electrodes is reduced even if the side margin portions are made thin.

[0010] In the multilayer ceramic capacitor of Patent Document 1, the external electrodes are exposed on the side surfaces of the multilayer ceramic capacitor, so when the multilayer ceramic capacitors are mounted at high density on a circuit board, there is a risk of a short circuit between the external electrodes of adjacent multilayer ceramic capacitors.

[0011] Hereinafter, embodiments of the multilayer ceramic electronic component and the method for manufacturing the multilayer ceramic electronic component of the present disclosure will be described with reference to the drawings. In the following, the case where the multilayer ceramic electronic component is a multilayer ceramic capacitor will be described. Note that the method for manufacturing the multilayer ceramic electronic component of the present disclosure is not limited to the method for manufacturing a multilayer ceramic capacitor, and can also be applied to the method for manufacturing various multilayer ceramic electronic components such as a multilayer piezoelectric element, a multilayer thermistor element, a multilayer chip coil, and a ceramic multilayer substrate. Each of the drawings referred to below, except for the photograph shown in FIG. 4, is schematic, and the positions, dimensional ratios, etc. of the components of the multilayer ceramic electronic component are not necessarily illustrated accurately.

[0012] FIG. 1 is a perspective view showing an example of a multilayer ceramic electronic component according to an embodiment of the present disclosure, and FIG. 2 is an exploded perspective view showing the multilayer ceramic electronic component of FIG. 1. In an actual multilayer ceramic electronic component, components are firmly sintered and bonded to each other, so that it cannot be disassembled as shown in FIG. 2. FIG. 3 is a cross-sectional view showing an element component of the multilayer ceramic electronic component cut along the cut line AA in FIG. 2, and FIG. 4 is a photograph showing a part of the multilayer ceramic electronic component cut along the cut line AA in FIG. 2. FIG. 4 shows a portion of the element component near the end face and a portion of the external electrode on the element component side. FIG. 5A is a perspective view showing a state where a plurality of conventional multilayer ceramic electronic components are mounted on a mounting substrate, FIG. 5B is a perspective view showing a state where a plurality of the multilayer ceramic electronic components of FIG. 1 are mounted on a mounting substrate, FIG. 6A is a cross-sectional view cut along the cut line BB in FIG. 5A, and FIG. 6B is a cross-sectional view cut along the cut line CC in FIG. 5B.

[0013] 1, the multilayer ceramic electronic component 1 of this embodiment includes an element component 2, a first external electrode 3a, a second external electrode 3b, and a protective layer 6. Hereinafter, the multilayer ceramic electronic component 1 may be referred to as a multilayer ceramic capacitor 1.

[0014] The element component 2 has a substantially rectangular parallelepiped shape, as shown in FIG. 2, for example. The element component 2 is a laminate in which a plurality of dielectric ceramic layers (hereinafter also simply referred to as ceramic layers) 4 and a plurality of internal electrode layers 5 having different polarities are alternately laminated, and a ceramic layer 4 is interposed between a pair of internal electrode layers 5 to which different polarities are imparted. The element component 2 has a first surface 7a and a second surface 7b that face each other in the lamination direction of the plurality of ceramic layers 4 and the plurality of internal electrode layers 5. The element component 2 also has a first end surface 8a and a second end surface 8b that face each other, and a first side surface 9a and a second side surface 9b that face each other. Hereinafter, the first surface 7a and the second surface 7b may be collectively referred to as the main surface 7a and the main surface 7b. The first end face 8a and the second end face 8b may be collectively referred to as end face 8a and end face 8b, and the first side face 9a and the second side face 9b may be collectively referred to as side face 9a and side face 9b. The ceramic layer 4 may contain a ceramic material such as BaTiO3 (barium titanate). The ceramic layer 4 may be mainly composed of barium titanate. The internal electrode layer 5 may contain a metal such as Ni (nickel), Pd (palladium), Cu (copper), Ag (silver), or an alloy thereof. The internal electrode layer 5 may be mainly composed of nickel or a nickel alloy.

[0015] The multiple internal electrode layers 5 are exposed on both the first side surface 9a and the second side surface 9b. Furthermore, the multiple internal electrode layers 5 are exposed on either the first end surface 8a or the second end surface 8b depending on the polarity. In other words, each of the multiple internal electrode layers 5 is exposed on the first end surface 8a or the second end surface 8b depending on the polarity applied to the internal electrode layer 5.

[0016] The first external electrode 3a is located on one of the first end face 8a and the second end face 8b (first end face 8a) as shown in FIG. 2, and is connected to the internal electrode layer 5 exposed on the end face. The second external electrode 3b is located on the other of the first end face 8a and the second end face 8b (second end face 8b) as shown in FIG. 2, and is connected to the internal electrode layer 5 exposed on the end face. The first external electrode 3a extends from the first end face 8a to at least one of the first face 7a and the second face 7b. The second external electrode 3b extends from the second end face 8b to at least one of the first face 7a and the second face 7b. On at least one of the main faces 7a and 7b, the first external electrode 3a and the second external electrode 3b extend a predetermined distance in a direction perpendicular to the end faces 8a and 8b. 1 and 2 show an example in which the first external electrode 3a and the second external electrode 3b extend from the end faces 8a and 8b to both the main faces 7a and 7b.

[0017] The first external electrode 3a and the second external electrode 3b each have a first external electrode side surface 3c and a second external electrode side surface 3d. The first external electrode side surface 3c and the second external electrode side surface 3d of the first external electrode 3a are flush with the first side surface 9a and the second side surface 9b, respectively, of the element component 2. The first external electrode side surface 3c and the second external electrode side surface 3d of the second external electrode 3b are flush with the first side surface 9a and the second side surface 9b, respectively, of the element component 2.

[0018] The protective layer 6 includes an insulating ceramic material. The protective layer 6 may include a ceramic material such as barium titanate. The protective layer 6 may be mainly composed of barium titanate. The protective layer 6 covers the side surface 9a and the side surface 9b of the element component 2, the external electrode side surface 3c and the external electrode side surface 3d of the first external electrode 3a, and the external electrode side surface 3c and the external electrode side surface 3d of the second external electrode 3b. In this embodiment, the first external electrode side surface 3c and the second external electrode side surface 3d of the first external electrode 3a are flush with the first side surface 9a and the second side surface 9b, respectively, and the first external electrode side surface 3c and the second external electrode side surface 3d of the second external electrode 3b are flush with the first side surface 9a and the second side surface 9b, respectively. This makes it possible to easily and accurately simultaneously form the protective layer 6 on the element component 2, the first external electrode 3a, and the second external electrode 3b, which include different materials.

[0019] When the first external electrode 3a extends from the first end face 8a to both the first face 7a and the second face 7b, and the second external electrode 3b extends from the second end face 8b to both the first face 7a and the second face 7b, the protective layer 6 has a substantially H-shaped shape when viewed from a direction perpendicular to the side faces 9a and 9b, as shown in Figs. 1 and 2. When the first external electrode 3a extends from the first end face 8a to one of the first face 7a and the second face 7b, and the second external electrode 3b extends from the second end face 8b to one of the first face 7a and the second face 7b, the protective layer 6 has a substantially U-shaped shape when viewed from a direction perpendicular to the side faces 9a and 9b. Note that in Fig. 1, for convenience of explanation, the boundary between the element part 2 and the protective layer 6 is shown by a two-dot chain line, but the actual boundary is not clearly visible.

[0020] In the multilayer ceramic capacitor 1 of this embodiment, the side surfaces 9a, 9b and the external electrode side surfaces 3c, 3d are covered with the protective layer 6 containing an insulating ceramic material, so that when multiple multilayer ceramic electronic components 1 are mounted on a circuit board, the multiple multilayer ceramic electronic components 1 can be arranged closely together while reducing short circuits between the multilayer ceramic electronic components 1. Therefore, the multilayer ceramic capacitor 1 of this embodiment can be mounted on a circuit board with high density.

[0021] In the multilayer ceramic capacitor 1, the region from the end of the side surface of the internal electrode layer 5 to the side surface of the element component is called a side margin. In the multilayer ceramic electronic component 1 of this embodiment, the protective layer 6 essentially functions as a side margin, but the thickness of the protective layer 6 can be made thin (for example, 30 μm or less). Therefore, in the multilayer ceramic electronic component 1, the area ratio of the internal electrode layer 5 can be increased to increase the obtained capacitance. The area ratio of the internal electrode layer 5 may be the ratio of the area of ​​the part where the multiple internal electrode layers 5 overlap each other to the area of ​​the element component 2 and the protective layer 6 when viewed from a plane (when viewed from a direction perpendicular to the main surface 7a and the main surface 7b). Note that the thinner the protective layer 6, the larger the area ratio of the internal electrode layer 5 can be, but from the viewpoint of protecting the side surface 9a and side surface 9b of the element component 2 and the external electrode side surface 3c and external electrode side surface 3d of the first external electrode 3a and the second external electrode 3b, the thickness of the protective layer 6 may be 5 μm or more and 30 μm or less.

[0022] Each of the first external electrode 3a and the second external electrode 3b may have an external electrode base layer 15 in contact with the element component 2. The element component 2 may have chamfered edges between the principal surfaces 7a, 7b and the end faces 8a, 8b, as shown in Fig. 3, for example. If the edges between the principal surfaces 7a, 7b and the end faces 8a, 8b are not chamfered, the thickness of the external electrode base layer 15 is likely to be thin at corners connecting the principal surfaces 7a, 7b and the end faces 8a, 8b when the external electrode base layer 15 is formed, and as a result, the external electrode base layer 15 becomes discontinuous, which may reduce the electrical reliability of the multilayer ceramic capacitor 1. Chamfering the edges between the principal surfaces 7a, 7b and the end surfaces 8a, 8b ensures a sufficient thickness of the external electrode base layer 15 even at corners connecting the principal surfaces 7a, 7b and the end surfaces 8a, 8b, improving the electrical reliability of the multilayer ceramic capacitor 1. The element component 2 may have a chamfer distance a of 3 μm or more, as shown in Fig. 3, for example. In this specification, the chamfer distance a refers to the shortest distance from the intersection line between the extended surfaces of the principal surfaces 7a, 7b and the extended surfaces of the end surfaces 8a, 8b to the surface of the element component 2.

[0023] Each of the first external electrode 3a and the second external electrode 3b may have a plated outer layer 16 located on the side of the external electrode base layer 15 opposite the element component 2 side. The multilayer ceramic capacitor 1 is mounted on a circuit board 42, for example, by joining the external electrodes 3 to electrode pads 41 provided on the circuit board 42 using a conductive bonding material such as solder 40 (see FIGS. 5B and 6B). The external electrodes 3 having the plated outer layer 16 can reduce corrosion of the external electrodes 3 and can strengthen the bonding between the multilayer ceramic capacitor 1 and the circuit board 42 by the conductive bonding material.

[0024] The external electrode base layer 15 may contain a ceramic material and a conductive metal material. The ceramic material of the external electrode base layer 15 may have a component that is the same as or similar to the main component of the ceramic layer 4 and the main component of the protective layer 6. The conductive metal material of the external electrode base layer 15 may have a component that is the same as or similar to the main component of the internal electrode layer 5. In this case, as described later, the bonding strength between the external electrode base layer 15 and the element part 2 and the protective layer 6 can be improved while reducing the decrease in the conductivity of the external electrode base layer 15, thereby improving the reliability of the multilayer ceramic capacitor. Here, the meaning of the main components being the same or similar, which will be described below, will be explained. In the case of ceramics and electrodes, the term "main component" refers only to the inorganic material component, even if they are composed of inorganic and organic materials. When the inorganic material portion of a ceramic or electrode is composed of a single component or multiple components, the component that makes up 80% cumulatively from the component with the largest proportion is called the main component, and this means that the components that make up the main component are the same. However, even if the main components are the same, variations in the composition ratio and particle size between them are allowed, so the expression "the main components are the same or similar" is used.

[0025] The external electrode base layer 15 may be formed by firing a conductive paste obtained by mixing a raw powder consisting of a dielectric ceramic powder and a conductive metal powder with a binder or the like. The conductive paste to be the external electrode base layer 15 may be applied to the element component 2 before firing the element component 2, and fired together with the element component 2. The plating outer layer 16 may be formed on the surface of the external electrode base layer 15 opposite to the element component 2 side after firing the element component 2 and the external electrode base layer 15. The external electrode base layer 15 or the plating outer layer 16 may be a single layer or multiple layers. For example, the plating outer layer 16 may have a lower layer on the external electrode base layer 15 side made of Ni and a surface layer made of Sn. A conductive resin layer may be provided instead of the plating outer layer 16.

[0026] Fig. 4 is a photograph showing the state of the joint between the end faces 8a, 8b of the element component 2 and the external electrode base layer 15 of the first external electrode 3a, 3b. The photograph in Fig. 4 was taken by observing the cross section of the multilayer ceramic capacitor 1 using a scanning electron microscope. As shown in Fig. 4, for example, the external electrode base layer 15 is a mesh-like matrix made up of a metal phase 45 (white area in Fig. 4) and a ceramic phase 46 (black area in Fig. 4) in a cross-sectional view. The internal electrode layer 5 of the element component 2 is formed in a layered manner up to the end faces 8a, 8b, and is sinter-bonded to the metal phase 45 of the external electrode base layer 15. The dielectric ceramic layer 4 of the element component 2 is sinter-bonded to the ceramic phase 46 of the external electrode base layer 15 at the end faces 8a, 8b. Although not shown, similar to the sintering bond between the dielectric ceramic layer 4 and the external electrode base layer 15 shown in Figure 4, the ceramic phases are also sintered together in the joint between the protective layer 6 and the external electrode base layer 15.

[0027] When the ceramic of the element component 2 and the ceramic of the external electrode base layer 15 are sinter-bonded at the end faces 8a and 8b, the ceramic regions of the element component 2 and the shapeless ceramic regions of the external electrode base layer 15 are integrated together, so that the external electrode base layer 15 is firmly bonded to the element component 2. Similarly, a strong bond can be achieved between the external electrode base layer 15 and the protective layer 6 by the sinter-bonded interface ceramic.

[0028] In order to realize a strong ceramic sinter bond and metal sinter bond, it is necessary to control the sintering behavior of the ceramic and metal materials to be sinter bonded. In this embodiment, the external electrode base layer 15 is composed of a ceramic material and a conductive metal material. The ceramic material of the external electrode base layer 15 may have a component that is the same as or similar to the main component of the ceramic layer 4 and the main component of the protective layer 6 of the element part 2. The conductive metal material of the external electrode base layer 15 may have a component that is the same as or similar to the main component of the internal electrode layer 5.

[0029] The element component 2, the first external electrode 3a and the second external electrode 3b attached to the element component 2, and the protective layer 6 attached to the element component 2 and the first external electrode 3a and the second external electrode 3b may be formed simultaneously by firing. By sintering the ceramic particles contained in the element component 2, the first external electrode 3a, the second external electrode 3b, and the protective layer 6 to each other during the firing process, these components are firmly fixed to each other, making it possible to obtain the desired functions of the multilayer ceramic capacitor 1. Ceramic materials with the same or similar main components have similar sintering temperatures, so sintering begins simultaneously and the ceramic particles are bonded to each other.

[0030] During firing, sintering bonds between the metal particles contained in the internal electrode layers 5 and the metal particles contained in the external electrode base layers 15 occur at bonding sites on the end faces 8a and 8b of the element component 2. The metal particles of the internal electrode layers 5 and the metal particles of the external electrode base layers 15 may be the same or similar materials that exhibit substantially the same behavior during firing.

[0031] The ratio of the metal phase 45 to the ceramic phase 46 in the external electrode base layer 15 may be controlled. Here, the ratio of the metal phase 45 to the ceramic phase 46 may be, for example, the ratio of the area of ​​the metal phase 45 to the area of ​​the ceramic phase 46 when the external electrode base layer 15 is viewed in cross section. When the ratio of the ceramic phase 46 is large, the bonding strength between the external electrode base layer 15 and the element part 2 and the protective layer 6 can be improved, but the conductivity of the external electrode base layer 15 decreases and the connection area with the internal electrode layer 5 decreases, which may result in an electrical open connection between the external electrode base layer 15 and the internal electrode layer 5. When the ratio of the ceramic phase 46 is small, a certain degree of bonding strength can be obtained by bonding the internal electrode layer 5 and the metal phase 45 at the end faces 8a and 8b of the element component 2, but the bonding strength between the external electrode base layer 15 and the protective layer 6 at the external electrode side faces 3c and 3d of the first external electrode 3a and the second external electrode 3b decreases, and there is a risk that the protective layer 6 will peel off from the element component 2 and the first external electrode 3a and the second external electrode 3b. In the external electrode base layer 15, the ratio of the region of the metal phase 45 to the region of the ceramic phase 46 in a cross-sectional view may be in the range of 40:60 to 80:20. In this case, it is possible to reduce a decrease in the conductivity of the external electrode base layer 15 while improving the bonding strength between the external electrode base layer 15 and the element component 2 and the protective layer 6. The ratio of the area of ​​the metal phase 45 to the area of ​​the ceramic phase 46 can be measured by observing a cross section of the external electrode base layer 15 using, for example, a scanning electron microscope.

[0032] When the ceramic layer 4 is mainly composed of ferroelectric barium titanate and the internal electrode layer 5 is mainly composed of nickel or a nickel alloy, the external electrode base layer 15 may be composed of a ceramic dielectric material mainly composed of barium titanate, the same as that of the ceramic layer 4, and a conductive metal material mainly composed of nickel or a nickel alloy, the same as that of the internal electrode layer 5. The protective layer 6 may be composed of a ceramic material mainly composed of barium titanate, the same as that of the ceramic layer 4.

[0033] As described above, in the multilayer ceramic electronic component 1 of this embodiment, the side surfaces 9a, 9b and the external electrode side surfaces 3c, 3d are covered with the protective layer 6 containing an insulating ceramic material, so that when multiple multilayer ceramic electronic components 1 are mounted on a circuit board, the multiple multilayer ceramic electronic components 1 can be arranged closely together while reducing short circuits between the multilayer ceramic electronic components 1. Below, with reference to Figures 5A, 5B, 6A, and 6B, advantageous effects of the multilayer ceramic capacitor 1 compared to conventional multilayer ceramic capacitors will be described.

[0034] 5A shows a state in which a conventional multilayer ceramic capacitor 50 not including a protective layer 6 is densely mounted on a circuit board 42. The distance s between adjacent multilayer ceramic capacitors is set taking into consideration the positions of the external electrodes of the multilayer ceramic capacitor, mounting accuracy, the effects of soldering, and the like, but in the conventional multilayer ceramic capacitor 50, the distance s between adjacent multilayer ceramic capacitors 50 is narrow, and when the first external electrodes 3a and the second external electrodes 3b are in contact or nearly in contact with each other, a short circuit or insulation deterioration is likely to occur.

[0035] 5B shows a state in which the multilayer ceramic capacitor 1 of this embodiment is densely mounted on a circuit board 42. In the multilayer ceramic capacitor 1 of this embodiment, the external electrode side surfaces 3c and 3d of the first external electrode 3a and the second external electrode 3b are covered with the protective layer 6, so that the risk of the first external electrode 3a and the second external electrode 3b coming into contact with each other and causing a short circuit can be effectively reduced. Therefore, the interval s between adjacent multilayer ceramic capacitors 1 can be narrowed, enabling high-density mounting.

[0036] 6A shows a state where adjacent multilayer ceramic capacitors 50 are short-circuited due to solder explosion 43 when conventional multilayer ceramic capacitors 50 are densely mounted on a circuit board 42. In the conventional multilayer ceramic capacitor 50, when the solder 40 is melted, gas generated from the first external electrode 3a and the second external electrode 3b (the first external electrode 3a in FIG. 6A) causes the solder 40 covering the surfaces of the first external electrode 3a and the second external electrode 3b (the first external electrode 3a in FIG. 6A) to scatter, forming a bridge between adjacent multilayer ceramic capacitors, and causing a short circuit. In the multilayer ceramic capacitor 1 of this embodiment, for example, as shown in FIG. 6B, the external electrode side surface 3c and the external electrode side surface 3d of the first external electrode 3a and the second external electrode 3b are covered with a protective layer 6, so that the short circuit between adjacent multilayer ceramic capacitors 1 due to the occurrence of solder explosion 43 can be reduced.

[0037] Next, a multilayer ceramic electronic component according to another embodiment of the present disclosure will be described.

[0038] Fig. 7 is a perspective view showing an example of a multilayer ceramic electronic component according to another embodiment of the present disclosure, and Fig. 8 is an exploded perspective view showing the multilayer ceramic electronic component of Fig. 7. A multilayer ceramic capacitor 1A of this embodiment differs from the multilayer ceramic capacitor 1 of the above embodiment in the configurations of a first external electrode 3a, a second external electrode 3b, and a protective layer 6, but has the same configuration as the multilayer ceramic capacitor 1 in the rest of the embodiment. Therefore, the same reference characters as those in the multilayer ceramic capacitor 1 are used for the similar configurations and detailed description thereof will be omitted.

[0039] In the multilayer ceramic capacitor 1A of this embodiment, as shown in FIG. 8, for example, the first external electrode 3a extends from the first end face 8a to one of the main faces 7a and 7b (the second face 7b in FIG. 8), and the second external electrode 3b extends from the second end face 8b to one of the main faces 7a and 7b (the second face 7b in FIG. 8). The protective layer 6 covers the first side face 9a and the second side face 9b of the element component 2, and the external electrode side faces 3c and 3d of the first external electrode 3a and the second external electrode 3b. The protective layer 6 has an inverted U-shape, as shown in FIGS. 7 and 8. Note that in FIG. 7, for convenience of explanation, the boundary between the element component 2 and the protective layer 6 is shown by a two-dot chain line, but the actual boundary is not clearly visible.

[0040] In the multilayer ceramic capacitor 1A, the interval s between adjacent multilayer ceramic capacitors 1A can be narrowed, similarly to the multilayer ceramic capacitor 1 of the above embodiment. Furthermore, in the multilayer ceramic capacitor 1A, the external electrodes 3 do not extend to the other of the main surfaces 7a and 7b of the element component 2 (the first surface 7a in FIG. 8), so that it is possible to increase the thickness of the element component 2 in the lamination direction without increasing the overall thickness of the multilayer ceramic capacitor 1A. As a result, it is possible to increase the obtained capacitance of the multilayer ceramic capacitor 1A while preventing the multilayer ceramic capacitor 1A from becoming too large.

[0041] Next, a multilayer ceramic electronic component according to still another embodiment of the present disclosure will be described.

[0042] Fig. 9 is a perspective view showing an example of a multilayer ceramic electronic component according to still another embodiment of the present disclosure, and Fig. 10 is a cross-sectional view taken along the cutting line DD in Fig. 9. The multilayer ceramic capacitor 1B of this embodiment is different from the multilayer ceramic capacitor 1 and the multilayer ceramic capacitor 1A of the above embodiments in the configuration of the protective layer 6, but has other similar configurations. Therefore, similar configurations are denoted by the same reference symbols as the multilayer ceramic capacitor 1 and the multilayer ceramic capacitor 1A, and detailed descriptions thereof will be omitted.

[0043] In the multilayer ceramic capacitor 1B of this embodiment, as shown in Fig. 9, for example, the protective layer 6 wraps around from the side surface 9a, 9b of the element component 2 and the external electrode side surface 3c, 3d of the first external electrode 3a, 3b to the main surface 7a, 7b of the element component 2. The protective layer 6 also wraps around the surfaces continuing to the external electrode side surface 3c, 3d of the first external electrode 3a, 3b. As shown in Fig. 10, for example, the protective layer 6 covers the element component 2 and the external electrode base layer 15 from the sides (left and right direction in Fig. 10), and wraps around the surfaces on the main surface 7a, 7b side of the external electrode base layer 15. The plated outer layer 16 is formed in the area on the surface of the external electrode base layer 15 where the protective layer 6 does not exist.

[0044] In the multilayer ceramic capacitor 1B, the protective layer 6 wraps around from the side surfaces 9a and 9b of the element component 2 to the main surfaces 7a and 7b. Therefore, when a plurality of multilayer ceramic capacitors 1B are mounted on a circuit board, the physical distance between the first external electrodes 3a and the second external electrodes 3b of adjacent multilayer ceramic capacitors 1B can be increased, thereby reducing the risk of short-circuiting between adjacent multilayer ceramic capacitors 1B. This in turn improves the reliability of the circuit board on which the multilayer ceramic capacitors 1B are densely mounted.

[0045] The protective layer 6 may extend from the first side surface 9a and the second side surface 9b of the element component 2 to the first surface 7a and the second surface 7b and the first end surface 8a and the second end surface 8b. In this case, the risk of short-circuiting between adjacent multilayer ceramic capacitors 1B can be effectively reduced, and the reliability of the circuit board on which the multilayer ceramic capacitors 1B are densely mounted can be further improved.

[0046] Next, a method for manufacturing a multilayer ceramic electronic component according to an embodiment of the present disclosure will be described with reference to Figures 11 to 21. In the method for manufacturing a multilayer ceramic electronic component according to the present embodiment, the form of the element component 2 changes in the green processing step before firing, so for ease of explanation, with reference to the exploded perspective view shown in Figure 2, the element component 2 on which the external electrode base layer 15 of the external electrode 3 is formed may be referred to as the second element component, and the second element component on which the protective layer 6 is formed may be referred to as the third element component.

[0047] First, a ceramic powder mixture of BaTiO3, the material of the ceramic layer 4, and additives is wet pulverized and mixed in a bead mill, and then a polyvinyl butyral binder, a plasticizer, and an organic solvent are added and mixed to prepare a ceramic slurry.

[0048] Next, a ceramic green sheet 10 is formed on the carrier film using a die coater. The thickness of the ceramic green sheet 10 may be, for example, about 0.5 μm to 10 μm. The thinner the ceramic green sheet 10 is, the larger the capacitance of the multilayer ceramic capacitor 1 can be. The method of forming the ceramic green sheet 10 is not limited to the method using a die coater, and a doctor blade coater, a gravure coater, or the like may also be used.

[0049] Next, as shown in Fig. 11, for example, a conductive paste 5a containing a metal material to become the internal electrode layers 5 is printed in a stripe pattern of multiple rows on the ceramic green sheet 10 formed above by gravure printing. The conductive paste 5a may contain metals such as Ni (nickel), Pd (palladium), Cu (copper), Ag (silver), etc., or alloys thereof. The method for printing the conductive paste 5a is not limited to gravure printing, and may be screen printing, etc.

[0050] As long as the characteristics of the capacitor can be ensured, the thinner the internal electrode layer 5, the more the internal defects caused by internal stress can be prevented. In the case of a multilayer ceramic capacitor with a high number of layers, the thickness of the internal electrode layer 5 may be about 1.5 μm or less.

[0051] Next, as shown in FIG. 12, a predetermined number of ceramic green sheets 10 on which an internal electrode layer pattern made of conductive paste 5a is printed are stacked, and finally a predetermined number of ceramic green sheets 10 are stacked. The ceramic green sheets 10 on which the internal electrode layer pattern is printed are stacked while being shifted by half the width of the internal electrode layer pattern. Although not shown, the ceramic green sheets 10 are stacked on a support sheet. As the support sheet, for example, an adhesive release sheet that can be adhered and released, such as a weak adhesive sheet or a foam release sheet, can be used.

[0052] Next, the laminate of the ceramic green sheets 10 is pressed in the lamination direction using a hydrostatic press to produce a base laminate 11 in which a plurality of ceramic green sheets 10 are integrated, as shown in FIG. 13, for example. In FIG. 13, imaginary division lines 30 are shown on the surface of the base laminate 11 by two-dot chain lines. Each part divided by the imaginary division lines 30 corresponds to the element component 2 shown in FIG. 3. The base laminate 11 has a pair of main surfaces, which correspond to the main surfaces 7a and 7b of the element component 2. The base laminate 11 has a pair of end surfaces, which correspond to the end surfaces 8a and 8b of the element component 2. The base laminate 11 has a pair of side surfaces, which correspond to the side surfaces 9a and 9b of the element component 2. Hereinafter, the parts of the intermediate body in each step of the manufacturing method of the multilayer ceramic electronic component may be specified by the names of the parts of the multilayer ceramic electronic component 1 corresponding to the parts. Although not shown, a support sheet used when laminating the plurality of ceramic green sheets 10 is present on the lower surface of the base laminate 11 .

[0053] Next, the base laminate 11 is cut at a predetermined interval using a press cutter to produce a plurality of first rod-shaped bodies 12. Hereinafter, the cutting of the base laminate 11 to obtain a plurality of first rod-shaped bodies 12 may be referred to as a first cut. The surfaces formed by the first cut in the first rod-shaped body 12 may be referred to as a first cut surface CP1 and a second cut surface CP2. The first cut surface CP1 and the second cut surface CP2 correspond to the first end surface 8a and the second end surface 8b of the element part 2, respectively, and expose the internal electrode layer 5 of one polarity among the internal electrode layers 5 of different polarities. The cutting of the base laminate 11 is not limited to cutting using a press cutter, and may be cutting using a dicing saw device, etc.

[0054] Next, as shown in FIG. 14, for example, a first cut is made on the base laminate 11, and then a V-shaped groove (hereinafter also referred to as a V groove) 19 having a depth of about 10 μm from the first surface 7a is formed at the position cut by the first cut. The V groove 19 can be formed, for example, by using a dicing saw device. Next, the support sheet is transferred to the opposite second surface 7b, and then a V groove 19 having a depth of about 10 μm from the second surface 7b is formed at the position cut by the first cut. The V groove 19 may be formed before the first cut is made.

[0055] The V-groove 19 is formed by chamfering the ridges that appear due to the first cut. By chamfering the ridges, the external electrode base layer 15 can be formed to have a thickness equal to or greater than a predetermined value. When viewed from the longitudinal direction (the direction perpendicular to the end face 8), the first rod-shaped body 12 has a shape, for example, as shown in FIG. 3. The chamfer distance b of the first rod-shaped body 12 may be 4 μm or more. Here, the chamfer distance b refers to the shortest distance from the intersection line where the extended plane of the main faces 7a and 7b intersect with the extended plane of the end faces 8a and 8b (the first cut face CP1 and the second cut face CP2) to the surface of the first rod-shaped body 12. When the chamfer distance b is 3 μm or less, the thickness of the external electrode base layer 15 is likely to be thin at the corners that connect the main faces 7a and 7b to the end faces 8a and 8b. As a result, the external electrode base layer 15 becomes discontinuous, which may reduce the electrical reliability of the multilayer ceramic capacitor. By chamfering the edges between the principal faces 7a, 7b and the end faces 8a, 8b, a sufficient thickness of the external electrode base layer 15 can be ensured even at the corners connecting the principal faces 7a, 7b and the end faces 8a, 8b, making it possible to improve the electrical reliability of the multilayer ceramic capacitor.

[0056] Next, as shown in FIG. 15, for example, the multiple first rod-shaped bodies 12 are arranged so that one of the first cut surface CP1 and the second cut surface CP2 (the first cut surface CP1 in FIG. 15) is located within one imaginary plane P. Although not shown, the multiple first rod-shaped bodies 12 are fixed on a support sheet 17. The imaginary plane P may be the surface of the support sheet 17. The support sheet 17 is for temporarily fixing the first rod-shaped bodies 12. Since it is necessary to remove the element parts 2 obtained by dividing the rod-shaped bodies from the support sheet 17 in a later step, the support sheet 17 may be a peelable adhesive sheet such as a high-temperature foaming adhesive sheet or a temperature-sensitive peeling adhesive sheet.

[0057] Next, as shown in Fig. 16, for example, an external electrode paste 21 that will become the external electrode base layer 15 is applied to the other of the first cut surface CP1 and the second cut surface CP2 of the first rod-shaped body 12 (the second cut surface CP2 in Fig. 16). In this embodiment, the second cut surface CP2 of the first rod-shaped body 12 is immersed in the external electrode paste 21 to a predetermined depth, and is then pulled up and dried. Next, the support sheet 17 is transferred, and the external electrode paste 21 is applied to the first cut surface CP1 of the first rod-shaped body 12 in a similar process.

[0058] The external electrode paste 21 is composed of an inorganic material, a binder, and a solvent. The inorganic material is composed of a ceramic material mainly composed of barium titanate, which is the same as or similar to the ceramic layer 4 of the element component 2, and a conductive metal material mainly composed of nickel or a nickel alloy, which is the same as or similar to the internal electrode layer 5. This allows the sintering behavior of the external electrode base layer 15 and the element component 2 at high temperatures to be similar in the subsequent firing process. As a result, the ceramic material of the external electrode base layer 15 and the dielectric ceramic layer 4 of the element component 2 are sinter-bonded, and the conductive metal material of the external electrode base layer 15 and the internal electrode layer 5 of the element component 2 are sinter-bonded, thereby making it possible to strengthen the bond between the external electrode base layer 15 and the element component 2.

[0059] Hereinafter, the first rod-shaped bodies 12 to which the external electrode paste 21 is applied may be referred to as second rod-shaped bodies 24 in order to distinguish them from the first rod-shaped bodies 12. Fig. 17 shows a plurality of aligned second rod-shaped bodies 24.

[0060] Next, as shown in FIG. 18, for example, a second cut is performed on the assembly of the second rod-shaped bodies 24 by using a cutter having a cutter blade 14. The assembly may be one in which the second rod-shaped bodies 24 are arranged such that one of the first cut surface CP1 and the second cut surface CP2 formed by the first cut (the first cut surface CP1 in FIG. 18) is located within one imaginary plane P. The imaginary plane P may be the surface of a cutting plate (not shown). In other words, the assembly may be one in which the second rod-shaped bodies 24 are assembled such that the longer side of the sides excluding the side extending in the longitudinal direction extends in the vertical direction. In this way, by assembling the second rod-shaped bodies 24 with the main surface 7a and the main surface 7b perpendicular to each other, the number of the second rod-shaped bodies 24 that can be cut at one time can be increased, and production efficiency can be improved.

[0061] 18, a pair of dummy members 37 may be arranged on both sides of an assembly of a plurality of second rod-shaped bodies 24 to sandwich the assembly from both sides, thereby fixing the plurality of second rod-shaped bodies 24. The pair of dummy members 37 may be cut together with the plurality of second rod-shaped bodies 24 in the second cut. When the plurality of second rod-shaped bodies 24 are arranged such that the main surfaces 7a and 7b of adjacent second rod-shaped bodies 24 face each other, the main surfaces 7a and 7b are perpendicular to the surface of the cutting plate, so that the number of second rod-shaped bodies 24 that can be placed on the cutting plate can be increased, thereby improving production efficiency. Furthermore, even if multiple second rod-shaped bodies 24 are assembled with their main surfaces 7a, 7b in contact with each other, as shown in FIG. 18, the only area in which they are actually in contact is a narrow region of the external electrode 3 (external electrode base layer 15), and therefore, when the second cut is made, the risk of the element components 2 coming into contact with each other and joining can be reduced.

[0062] Furthermore, because dummy members 37, which are cut together with the second rod-shaped body 24, are arranged on both sides, it is possible to reduce changes in the position or posture of the second rod-shaped body 24 during the second cutting. After the second cutting, the second rod-shaped body 24 becomes a chip-shaped component on which an external electrode base layer 15 is formed, and to distinguish it from the element component 2, the chip-shaped component is sometimes called the second element component 13.

[0063] 19, for example, the multiple second element parts 13 are arranged so that one of the third cut plane CP3 and the fourth cut plane CP4 formed by the second cut (the third cut plane CP3 in FIG. 19) is located within a single imaginary plane P. The imaginary plane P may be the surface of a supporting sheet 17, and the multiple second element parts 13 may be fixed onto the supporting sheet 17. The supporting sheet 17 is for temporarily fixing the second element parts 13, and since the second element parts 13 will be removed in a later process, a peelable adhesive sheet such as a high-temperature foaming adhesive sheet or a temperature-sensitive peeling adhesive sheet is used as the supporting sheet 17.

[0064] Next, a protective layer 6 containing a ceramic material is formed on the side surface of the second element part 13. As shown in FIG. 20, the side surface (fourth cut surface CP4) of the second element part 13 facing upward in FIG. 19 is turned downward, immersed in ceramic paste 20 contained in a pool 22, pulled out, and then dried. Next, the support sheet 17 is transferred to the surface on which the ceramic paste 20 has been applied, and the same process is repeated to dip-apply the ceramic paste 20 to the opposite side surface (third cut surface CP3), and then dried. The dried ceramic paste 20 is the protective layer 6, and wraps around from the side surface 9a, side surface 9b, external electrode side surface 3c, and external electrode side surface 3d of the second element part 13 to the adjacent surfaces adjacent thereto. The thickness of the protective layer 6 after drying may be 5 μm to 30 μm. If the amount of wraparound of the protective layer 6 to the adjacent surface is increased, the surface area of ​​the first external electrode 3a and the second external electrode 3b will decrease, which may make it difficult to mount the electrodes on a circuit board. Therefore, the amount of wraparound of the protective layer 6 to the adjacent surface may be in the range of 0 μm to 50 μm. The ceramic paste 20 may have a component that is the same as or similar to the main component of the ceramic layer 4 and the main component of the protective layer 6. Instead of the ceramic paste 20, a ceramic slurry that has a component that is the same as or similar to the main component of the ceramic layer 4 and the main component of the protective layer 6 may be used. In addition, when forming the protective layer 6, a support sheet 17 to which a plurality of second element components 13 are fixed may be fixed on a flat plate 28, as shown in FIG. 20, for example. This can improve the handleability of the plurality of second element components 13.

[0065] Fig. 21 shows a third element part 27 on which a protective layer 6 is formed, obtained in the step of Fig. 20. Since the third element part 27 will shrink and sinter uniformly in the subsequent firing step, Fig. 21 shows the third element part 27 before firing as well as the third element part 27 after firing.

[0066] Next, third element part 27 is barrel polished and chamfered. Chamfering is performed to round off the corners of third element part 27 and remove burrs. In this embodiment, the sintered third element part 27 and an abrasive are placed in a pot containing water and rotated to perform polishing.

[0067] Next, a plated outer layer 16 is formed on the surface of the external electrode base layer 15. In this embodiment, a plurality of plated outer layers 16 are formed. First, a Ni plating layer is formed on the surface of the external electrode base layer 15 in an electrolytic plating tank. Furthermore, a Sn plating layer is formed on the surface of the Ni plating layer, thereby manufacturing the multilayer ceramic capacitor 1 shown in FIG. 9.

[0068] Next, a method for manufacturing a multilayer ceramic electronic component according to another embodiment of the present disclosure will be described with reference to Figures 22 to 26. The method for manufacturing a multilayer ceramic electronic component according to this embodiment is a method for manufacturing the multilayer ceramic capacitor 1 shown in Figure 1, and is the same as the method for manufacturing a multilayer ceramic electronic component according to the above embodiment up to the step of obtaining a second rod-shaped body 24 (see Figure 17) on which an external electrode base layer 15 is formed.

[0069] First, as shown in FIG. 22A, for example, the second rod-shaped bodies 24 shown in FIG. 17 are aligned and assembled on an adhesively removable support sheet 17 with the main surfaces 7a and 7b facing each other, and a thermoplastic resin sheet 34 is placed above them. Furthermore, flat plates 28 are placed above and below the second rod-shaped bodies 24, the resin sheet 34, and a frame-shaped or columnar spacer 36 surrounding the second rod-shaped bodies 24 placed on the support sheet 17. The height of the spacer 36 is set to be about 0 to 0.1 mm higher than the height of the second rod-shaped bodies 24. The height of the spacer 36 may depend on the dimensions of the multilayer ceramic capacitor to be manufactured, but by setting the height to a level that includes the variation in height of the second rod-shaped bodies 24, the amount of resin used in the subsequent steps can be reduced.

[0070] Next, as shown in FIG. 22B, for example, the resin sheet 34 is heated while being pressed in the direction indicated by the arrow F. The resin sheet 34 melts due to the heating and flows into the gaps between the adjacent second rods 24. At this time, the frame-shaped or columnar spacer 36 ensures the intervals between the flat plates 28 arranged above and below the second rods 24, and reduces the outflow of the molten resin sheet 34. The molten resin sheet 34 is then cooled to produce an assembly 23 (also called a flat rod block) in which the gaps between the adjacent second rods 24 are filled with the thermoplastic resin 33 and the periphery is covered with the thermoplastic resin 33.

[0071] Next, as shown in FIG. 23, for example, the cutting blade 14 is used to cut the assembly 23 at a predetermined interval in a direction perpendicular to the longitudinal direction of the second rod-shaped body 24 (second cut), to produce a third rod-shaped body 25 having a third cut surface CP3 and a fourth cut surface CP4 facing each other. The cutting of the assembly 23 is not limited to cutting using the cutting blade 14, but may be cutting using a dicing saw device or the like. The third rod-shaped body 25 is formed by integrating chip-shaped element components on which the external electrode base layer 15 is formed in a line. This makes it possible to improve the handling properties in the subsequent steps, and ultimately to improve the productivity of the multilayer ceramic capacitor 1.

[0072] Next, each of the multiple third rod-shaped bodies 25 is rotated 90 degrees around the longitudinal axis so that one of the third cut surface CP3 and the fourth cut surface CP4 (the fourth cut surface CP4 in Figure 24) where the internal electrode layer 5 is exposed faces upward.

[0073] Next, the third rod-shaped bodies 25 are assembled with one of the third cut surface CP3 and the fourth cut surface CP4 (the fourth cut surface CP4 in FIG. 24) facing upward. Then, as shown in FIG. 24, for example, ceramic green sheets 10 to become the protective layers 6 are arranged on the upper and lower surfaces of the assembly of the third rod-shaped bodies 25. The ceramic green sheets 10 do not have to be arranged on the upper and lower surfaces of the assembly at the same time, but may be arranged on each surface.

[0074] Next, the assembly with the ceramic green sheets 10 arranged on the upper and lower surfaces is subjected to isostatic pressing to adhere the ceramic green sheets 10 that will become the protective layer 6. FIG. 25 shows the assembly after isostatic pressing. The third rod-shaped body 25 becomes the fourth rod-shaped body 26 to which the ceramic green sheets 10 that will become the protective layer 6 are attached. In this way, the protective layer 6 can be formed into a plurality of third rod-shaped bodies 25 by bringing the ceramic green sheets 10 into contact with the third cut surface CP3 and the fourth cut surface CP4, transferring the portion of the ceramic green sheet 10 that is in contact with the third cut surface CP3 to the third cut surface CP3, and transferring the portion of the ceramic green sheet 10 that is in contact with the fourth cut surface CP4 to the fourth cut surface CP4. The ceramic green sheet 10 that will become the protective layer 6 may be a single-layer ceramic green sheet or may be a multi-layer ceramic green sheet. The multi-layer ceramic green sheets may have different components from each other.

[0075] Next, the fourth rod-shaped bodies 26 are degreased and fired. A plurality of the fourth rod-shaped bodies 26 are arranged on a zirconia plate, and the plurality of the fourth rod-shaped bodies 26 arranged on the plate are placed in a degreasing furnace to remove the solvent and binder, and then fired in a high-temperature firing furnace. The degreasing is performed in air at room temperature to about 300°C to remove the solvent and plasticizer, and then in a nitrogen atmosphere up to 800°C to remove the binder and resins such as the fixing resin by thermal decomposition and combustion. In the firing process, firing may be performed, for example, at a temperature of 1100 to 1250°C in a hydrogen mixed atmosphere.

[0076] 26, in the fourth rod-shaped body 26 after sintering, the thermoplastic resin 33 surrounding the third rod-shaped body 25 is decomposed and burned away, leaving gaps 31 between adjacent third element components 27. Furthermore, the third element components 27 shrink during the sintering process, widening the gaps between the third element components 27, causing cracks to appear in the sintered ceramic green sheet 10 at locations between the third element components 27, forming division lines 32. As a result, the multiple third element components 27 on which the external electrodes 3 and protective layers 6 are formed are essentially divided into individual pieces.

[0077] Next, the third element component 27 is subjected to barrel polishing and chamfered. The chamfering step is the same as in the above embodiment, and sintered residues of the ceramic green sheets generated between the third element components 27 are removed by barrel polishing. The steps following the chamfering step are the same as in the above embodiment, and therefore will not be described in detail.

[0078] Next, a method for manufacturing a multilayer ceramic capacitor according to still another embodiment of the present disclosure will be described with reference to Figs. 27 to 32. The method for manufacturing a multilayer ceramic electronic component according to this embodiment is the same as the method for manufacturing a multilayer ceramic electronic component according to the above embodiment up to the point where base laminate 11 shown in Fig. 13 is obtained. Since the support sheet is omitted in Fig. 13, base laminate 11 laminated on support sheet 18 is shown in Fig. 27. As for support sheet 18, a high-temperature foaming adhesive sheet or a temperature-sensitive peeling adhesive sheet that loses its adhesive force at high temperatures, similar to support sheet 17, can be used.

[0079] First, as shown in FIG. 28, for example, the base laminate 11 is cut at a predetermined interval using a press cutter to produce a plurality of first rod-shaped bodies 12. In this embodiment, the support sheet 18 is cut together with the base laminate 11. The first cut surface CP1 and the second cut surface CP2 formed by the first cut correspond to the first end surface 8a and the second end surface 8b of the element part 2 shown in FIG. 8, respectively. The plurality of internal electrode layers 5 are exposed at either the first cut surface CP1 or the second cut surface CP2 according to polarity. The cutting of the base laminate 11 is not limited to cutting using a press cutter, and may be cutting using a dicing saw device, etc.

[0080] Next, V-grooves 19 having a depth of about 10 μm from the main surfaces 7a and 7b are formed at the positions cut by the first cut. The V-grooves 19 can be formed, for example, by using a dicing saw device. The V-grooves 19 are formed by chamfering the edges that appear in the first cut. By chamfering the edges, an external electrode base layer 15 having a thickness equal to or greater than a predetermined value can be formed. The V-grooves 19 may be formed before the first cut.

[0081] Next, as shown in Fig. 29, for example, the multiple first rod-shaped bodies 12 are arranged and fixed on a support sheet 17 so that one of the first cut surface CP1 and the second cut surface CP2 (the second cut surface CP2 in Fig. 29) faces upward. The support sheet 17 is for temporarily fixing the first rod-shaped bodies 12. As the support sheet 17, a peelable adhesive sheet such as a high-temperature foaming adhesive sheet or a temperature-sensitive peeling adhesive sheet can be used.

[0082] Next, as shown in FIG. 30, for example, the external electrode paste 21 that will become the external electrode base layer 15 is applied to one of the first cut surface CP1 and the second cut surface CP2 of the first rod-shaped body 12 shown in FIG. 29 (the second cut surface CP2 in FIG. 30). In this embodiment, the second cut surface CP2 of the first rod-shaped body 12 with the support sheet 18 is immersed to a predetermined depth in the external electrode paste 21 contained in the pool 22, pulled up, and then dried. Next, the support sheet 18 is transferred, and the external electrode paste 21 is applied to the other of the first cut surface CP1 and the second cut surface CP2 of the first rod-shaped body 12 (the first cut surface CP1 in FIG. 30) in a similar process. When forming the external electrode base layer 15, the support sheet 17 to which the multiple first rod-shaped bodies 12 are fixed may be fixed on a flat plate 28, as shown in FIG. 30, for example. This can improve the handleability of the multiple first rod-shaped bodies 12.

[0083] The external electrode paste 21 is composed of an inorganic material, a binder, and a solvent. The inorganic material is composed of a ceramic dielectric material mainly composed of barium titanate, the same as the element component, and a conductive metal material mainly composed of nickel or nickel alloy, the same as the internal electrode layer. This makes it possible to make the sintering behavior of the external electrode base layer 15 and the element component 2 similar at high temperatures in the subsequent firing process. As a result, it becomes possible to sinter-bond the ceramic material of the external electrode base layer 15 and the dielectric ceramic layer 4 of the element component 2, and to sinter-bond the conductive metal material of the external electrode base layer 15 and the internal electrode layer 5 of the element component 2, thereby strengthening the bond between the external electrode base layer 15 and the element component 2.

[0084] The external electrode base layer 15 is also formed on a support sheet 18 located on a first surface 7a of a second rod-shaped body 24 (a first rod-shaped body 12 to which the external electrode paste 21 is applied), as shown in Fig. 31, for example. In this embodiment, a high-temperature foaming adhesive sheet or a temperature-sensitive peeling adhesive sheet that loses its adhesive force at high temperatures is used as the support sheet 18, so that when the external electrode paste 21 is dried, the support sheet 18 is peeled off from the second rod-shaped body 24 along a separation line 39 shown in Fig. 31. Fig. 32 shows a plurality of second rod-shaped bodies 24 from which the support sheet 18 has been peeled off.

[0085] The subsequent steps are the same as those in the above embodiment shown in FIG. 17 and subsequent steps, and therefore a detailed description thereof will be omitted.

[0086] The present disclosure may have the following embodiments.

[0087] The multilayer ceramic electronic component of the present disclosure includes a substantially rectangular parallelepiped element component, a first external electrode, a second external electrode, and a protective layer. The element component is formed by alternately stacking a plurality of ceramic layers and a plurality of internal electrode layers having different polarities, and has a first surface and a second surface facing each other in a stacking direction of the plurality of ceramic layers and the plurality of internal electrode layers, a first end surface and a second end surface facing each other, and a first side surface and a second side surface facing each other. The plurality of internal electrode layers are exposed to the first side surface and the second side surface, and are exposed to either the first end surface or the second end surface according to polarity. The first external electrode is connected to the internal electrode layer exposed to the first end surface, and the second external electrode is connected to the internal electrode layer exposed to the second end surface. Each of the first external electrode and the second external electrode extends over at least one of the first surface and the second surface, and has a first external electrode side surface and a second external electrode side surface that are flush with the first side surface and the second side surface, respectively. The protective layer includes a ceramic material and covers the first side surface and the second side surface and the first external electrode side surface and the second external electrode side surface of the first external electrode and the second external electrode.

[0088] In addition, a method for manufacturing a multilayer ceramic electronic component disclosed herein includes cutting a master laminate formed by alternately stacking a plurality of ceramic green sheets and a plurality of internal electrode layers at predetermined intervals to produce a first rod-shaped body having first and second surfaces and first and second cut surfaces, chamfering edges between the first and second surfaces and the first and second cut surfaces, and forming first and second external electrodes extending from each of the first and second cut surfaces to at least one of the first and second surfaces to produce a second rod-shaped body, cutting the second rod-shaped body at predetermined intervals in a direction perpendicular to a longitudinal direction of the second rod-shaped body to form third and fourth cut surfaces at which the plurality of internal electrode layers are exposed, and forming a protective layer containing a ceramic material on each of the third and fourth cut surfaces.

[0089] When the multilayer ceramic electronic component of the present disclosure is mounted on a circuit board, the risk of short-circuiting between the external electrodes of adjacent multilayer ceramic electronic components can be reduced, making it possible to mount the multilayer ceramic electronic components on the circuit board with high density.

[0090] Furthermore, according to the method for producing a multilayer ceramic electronic component of the present disclosure, the above-mentioned multilayer ceramic electronic component can be produced with reduced manufacturing burden and with good productivity.

[0091] The methods, devices, materials, etc. used in each embodiment are not limited to the embodiment, and may be used in combination. For example, the protective layer may be applied by attaching a ceramic green sheet to the rod-shaped body or element part, or the rod-shaped body or element part may be dip-coated with a ceramic slurry. In addition, although the material of the protective layer and the material of the element part are substantially the same material or similar materials in the embodiments, the material of the protective layer and the material of the element part may be different as long as a strong bond between the element part and the protective layer can be ensured. In this way, changing the processing conditions of each embodiment or adding a new process to each embodiment does not affect the gist of the present disclosure. [Explanation of symbols]

[0092] 1,1A,1B Multilayer ceramic electronic components (multilayer ceramic capacitors) 2. Base parts 3a 1st external electrode 3b 2nd external electrode 3c 1st external electrode side (external electrode side) 3d 2nd external electrode side (external electrode side) 4 Dielectric ceramic layer (ceramic layer) 5 Internal electrode layer 5a Conductive paste 6 Protective layer 7a 1st surface (main surface) 7b 2nd surface (main surface) 8a 1st end face (end face) 8b Second end face (end face) 9a 1st side (end surface) 9b 2nd side (side) 10 Ceramic green sheet 11 Mother laminate 12 First rod-shaped body 13 Second body part 14 Push cutting blade 15 External electrode base layer 16 Outer layer 17,18 Support sheet 19 groove (V groove) 20 Ceramic Paste 21 External electrode paste 22 Pool 23 Aggregate 24 Second rod-shaped body 25 Third rod-shaped body 26 4th rod-shaped body 27 Third body part 28 flat plate 30 Virtual division line 31 void 32 Division Line 33 Thermoplastic resin 34 Resin sheet 36 Spacer 37 Dummy parts 39 Separation Line 41 Electrode Pads 42 Circuit Board 43 Solder Explosion 45 Metal phase 46 Ceramic Phase 50 Multilayer ceramic capacitors CP1 1st cutting plane CP2 2nd cutting plane CP3 3rd cutting plane CP4 4th cutting plane

Claims

1. The insulating film includes a substantially rectangular parallelepiped element component, a first external electrode, a second external electrode, and a protective layer, the element part is formed by alternately laminating a plurality of ceramic layers and a plurality of internal electrode layers having different polarities, and has a first surface and a second surface opposing each other in a lamination direction of the plurality of ceramic layers and the plurality of internal electrode layers, a first end surface and a second end surface opposing each other, and a first side surface and a second side surface opposing each other, the plurality of internal electrode layers being exposed to the first side surface and the second side surface, and being exposed to either the first end surface or the second end surface according to polarity, the first external electrode is connected to an internal electrode layer exposed at the first end surface, and the second external electrode is connected to an internal electrode layer exposed at the second end surface; each of the first external electrode and the second external electrode extends over at least one of the first surface and the second surface, and has a first external electrode side surface and a second external electrode side surface that are flush with the first side surface and the second side surface, The protective layer includes a ceramic material and covers the first side surface and the second side surface and the first external electrode side surface and the second external electrode side surface of the first external electrode and the second external electrode.

2. each of the first external electrode and the second external electrode has an external electrode base layer in contact with the element component; the external electrode base layer includes a ceramic material and a conductive metal material, the ceramic material of the external electrode base layer has a component that is the same as or similar to a main component of the plurality of ceramic layers and a main component of the protective layer, 2. The multilayer ceramic electronic component according to claim 1, wherein the conductive metal material of the external electrode base layers has a component that is the same as or similar to a main component of the plurality of internal electrode layers.

3. 3. The multilayer ceramic electronic component according to claim 2, wherein in the external electrode base layer, an area ratio of a metal phase region to a ceramic phase region is in the range of 40:60 to 80:20 in a cross-sectional view.

4. The main component of the protective layer is barium titanate, 4. The multilayer ceramic electronic component according to claim 2, wherein the main component of said conductive metal material of said external electrode base layers is nickel or a nickel alloy.

5. 5. The multilayer ceramic electronic component according to claim 1, wherein the protective layer wraps around the first and second surfaces of the base component, and the surfaces of the first and second external electrodes that are continuous with the first and second external electrode side surfaces.

6. 6. The multilayer ceramic electronic component according to claim 1, wherein edges between the first and second faces and the first and second end faces of the element component are chamfered.

7. cutting a base laminate in which a plurality of ceramic green sheets and a plurality of internal electrode layers are alternately laminated at a predetermined interval to prepare a first rod-shaped body having a first surface, a second surface, a first cut surface, and a second cut surface; chamfering edges between the first surface and the second surface and the first cut surface and the second cut surface, and forming a first external electrode and a second external electrode extending from each of the first cut surface and the second cut surface to at least one of the first surface and the second surface, to produce a second rod-shaped body; cutting the second rod-shaped body at predetermined intervals in a direction perpendicular to a longitudinal direction of the second rod-shaped body to form third cut surfaces and fourth cut surfaces at which the plurality of internal electrode layers are exposed; forming a protective layer containing a ceramic material on each of the third cut surface and the fourth cut surface.

8. the ceramic material of the protective layer is a single-layer or multiple-layer ceramic green sheet, 8. The method for manufacturing a laminated ceramic electronic component according to claim 7, wherein forming the protective layer includes contacting the ceramic green sheet with the third cut surface and the fourth cut surface and transferring portions of the ceramic green sheet in contact with the third cut surface and the fourth cut surface to the third cut surface and the fourth cut surface.

9. the ceramic material of the protective layer is a ceramic paste; 8. The method for producing a laminated ceramic electronic component according to claim 7, wherein the formation of the protective layer includes immersing the third cut surface and the fourth cut surface in a ceramic paste, and then pulling them out and drying them.

10. 8. The method for manufacturing a laminated ceramic electronic component according to claim 7, wherein the cutting of the second rod-shaped bodies is performed by forming a group of the second rod-shaped bodies into an assembly in which one of the first cut surface and the second cut surface is located within a single imaginary plane, and by arranging dummy members around the assembly.

11. 8. The method for manufacturing a laminated ceramic electronic component according to claim 7, wherein the cutting of the second rod-shaped bodies is performed after forming a group of the second rod-shaped bodies into an assembly in which one of the first cut surface and the second cut surface is located within a single imaginary plane, and fixing the assembly with a thermoplastic resin.

12. The preparation of the first rod-shaped body includes cutting the base laminate attached to a support sheet together with the support sheet to form the first rod-shaped body to which a portion of the support sheet is attached; 8. The method for manufacturing a laminated ceramic electronic component according to claim 7, wherein the preparation of the second rod-shaped body includes forming the first external electrode and the second external electrode on the first rod-shaped body to which the portion of the support sheet is attached, and then peeling the portion of the support sheet from the first rod-shaped body.

Images