Multilayer ceramic electronic component and its manufacturing method

Abstract

This method for manufacturing a multilayer ceramic electronic component comprises: a step for alternately stacking a plurality of ceramic green sheets and a plurality of internal electrodes to obtain a mother stack in which an electrode pattern protected with a resin layer is laid out on at least one major surface of the stack; a step for obtaining a rectangular elemental component by cutting the mother stack along a planned cutting line orthogonal thereto; and a step for removing the resin layer of the elemental component by firing. The method includes a step for chamfering a ridge portion of the elemental component prior to firing.

Description

[Technical Field]

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

[0002] Prior art multilayer ceramic electronic components and manufacturing methods thereof are described in, for example, Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5535765 [Patent Document 2] Patent No. 4425688 Summary of the Invention

[0004] The multilayer ceramic electronic component of the present disclosure includes a laminate in which dielectric layers and internal electrodes are alternately stacked, surface electrodes provided on at least one of a first surface and a second surface of the laminate, and external electrodes connecting the surface electrodes and the internal electrodes, wherein the surface electrodes are thicker than the internal electrodes and are positioned continuously with a uniform thickness along at least one of the first surface and the second surface of the laminate.

[0005] The method for manufacturing a multilayer ceramic electronic component of the present disclosure includes the steps of alternately stacking a plurality of ceramic green sheets and a plurality of internal electrodes to obtain a laminate; obtaining a base laminate having surface electrodes and a resin layer protecting the surface electrodes on at least one of a first surface and a second surface of the laminate; cutting the base laminate along cutting lines perpendicular to the base laminate to obtain a rectangular element precursor; removing the resin layer from the element precursor by firing; and chamfering the edges of the element precursor before firing. [Brief explanation of the drawings]

[0006] The objects, features, and advantages of the present disclosure will become more apparent from the following detailed description and drawings. [Figure 1] FIG. 1 is a perspective view of a via array capacitor, which is a type of multilayer ceramic electronic component according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an exploded perspective view schematically showing a stacked state of sheets on which a conductive paste is printed. [Figure 3] FIG. 2 is a perspective view of a base laminate of a via array type capacitor. [Figure 4A] FIG. 10 is a cross-sectional view of a precursor element of a via array type capacitor cut at a position passing through the center of a through conductor. [Figure 4B] FIG. 2 is a cross-sectional view of an element precursor after barrel polishing. [Figure 4C] FIG. 10 is a cross-sectional view of the element part after firing. [Figure 5A] FIG. 1 is a perspective view of a typical multilayer ceramic capacitor. [Figure 5B] FIG. 1 is a perspective view of a multilayer ceramic capacitor known as a three-terminal capacitor. [Figure 6A] FIG. 5B is a perspective view showing the element part of FIG. 5A in which external electrodes are formed by direct plating. [Figure 6B] FIG. 5C is a perspective view showing the element part of FIG. 5B in which external electrodes are formed by direct plating. [Figure 7] FIG. 2 is an exploded perspective view schematically showing a stack of ceramic green sheets on which internal electrodes are printed, in a configuration corresponding to one component. [Figure 8] FIG. [Figure 9] FIG. 2 is a perspective view of an element precursor obtained by cutting a base laminate. [Figure 10A] FIG. 10 is a cross-sectional view of the element precursor of FIG. 9 taken along the AA' plane. [Figure 10B] FIG. 2 is a cross-sectional view of an element precursor after barrel polishing. [Figure 10C] FIG. 10 is a cross-sectional view of the element part after firing. DETAILED DESCRIPTION OF THE INVENTION

[0007] First, a multilayer ceramic electronic component and a method for manufacturing the same, which have a configuration on which the multilayer ceramic electronic component and the method for manufacturing the same according to the present disclosure are based, will be described.

[0008] In recent years, the miniaturization of electronic components mounted on wiring boards of electronic devices has progressed, with the multilayer ceramic electronic component and its manufacturing method based on the configuration of the multilayer ceramic electronic component disclosed herein. Some multilayer ceramic electronic components with built-in internal electrodes have electrode pads or electronic circuits laid on their main surfaces. These surface electrodes have been chamfered and then attached to their main surfaces by methods such as printing, vapor deposition, or immersion. Chamfering is performed before laying the surface electrodes because chamfering using methods such as barrel polishing or sandblasting, which involve polishing the surface electrodes in a rotating pot with an abrasive, can damage the surface electrodes. However, as components become smaller, it has become increasingly difficult to lay electrode patterns with high precision on individual components. For this reason, several methods have been proposed.

[0009] For example, in the aforementioned Patent Document 1, grooves are formed with a laser along the outline of the product area on the surface of a base laminate formed by laminating and integrating internal electrodes and ceramic green sheets, and the surface is chamfered. Break grooves are then formed, and the base laminate is broken after firing and separated into individual products. Since surface electrodes can be formed on the main surfaces of the base laminate before breaking, which has already been chamfered, electrodes can be formed with high positional accuracy.

[0010] Furthermore, for example, the aforementioned Patent Document 2 provides a method for forming external electrodes by direct plating even when the base component, which is the main body of a multilayer ceramic electronic component, is chamfered. This method involves placing anchor tabs between dielectric layers close to the main surfaces and narrowing the distance between the exposed portions of the anchor tabs toward the top and bottom surfaces. Direct plating of external electrodes on such a structure results in good bonding with the internal electrodes, no misalignment, and high-precision, high-resolution external electrodes. Furthermore, the document claims that external electrodes can be formed with high reliability through plating even on rounded corners.

[0011] However, in the method described in the aforementioned Patent Document 1, grooves are formed in the base laminate using a laser for chamfering, which requires more labor and costs than barrel polishing, another conventional technology that performs chamfering all at once, and this places a burden on production.

[0012] Furthermore, in the method described in Patent Document 2, the distance between the exposed portions of adjacent anchor tabs must be made closer toward the top surface and the bottom surface, which necessitates the preparation of ceramic green sheets with a variety of thicknesses for the anchor tabs. The anchor tabs are dummy electrodes that are not involved in the formation of capacitance, and their exposed portions act as starting points for plating growth, forming plating films that become external electrodes and also serving to fix the plating film to the ceramic body.

[0013] In view of the above, an object of the present disclosure is to provide a multilayer ceramic electronic component that can be easily chamfered without damaging the electrodes on the main surfaces, and a method for manufacturing the same.

[0014] Hereinafter, with reference to the drawings, embodiments of the multilayer ceramic electronic component and the manufacturing method thereof according to the present disclosure will be described, taking as an example a multilayer ceramic capacitor as an example of the multilayer ceramic electronic component. The multilayer ceramic electronic component to which the present disclosure is directed is not limited to a multilayer ceramic capacitor, and can be applied to various other multilayer ceramic components such as a multilayer piezoelectric element, a multilayer thermistor element, a multilayer chip coil, and a ceramic multilayer substrate, as long as the electronic component has surface electrodes on its main surfaces.

[0015] (First embodiment) FIG. 1 is a perspective view of a via array type capacitor 23, which is a type of multilayer ceramic capacitor according to an embodiment of the present disclosure and is arranged in close proximity to an LSI on a circuit board. FIG. 2 is an exploded perspective view schematically showing the stacked state of sheets on which conductive paste is printed. FIG. 3 is a perspective view of a base laminate 11 of the via array type capacitor 23. This type of capacitor has a structure that reduces inductance, enabling high-speed power supply to an LSI (Large Scale Integration). In the following first embodiment of a multilayer ceramic electronic component, the via array type capacitor 23 will be used as an example for explanation.

[0016] The via array type capacitor 23 of this embodiment includes a laminate in which dielectric ceramic layers 4 and internal electrodes 5 are alternately stacked, surface electrodes 14 formed by electrode films provided on both ends of each of the first and second surfaces of the laminate, and through conductors 20 connecting the surface electrodes 14 and the internal electrodes 5. The thickness of the surface electrodes 14 is greater than the thickness of the internal electrodes 5, and the surface electrodes 14 are positioned continuously with a uniform thickness along at least one of the first and second surfaces of the laminate.

[0017] The surface electrode 14 and the internal electrodes 5 each contain a ceramic component, and the amount of ceramic component in the surface electrode 14 may be greater than the amount of ceramic component in each internal electrode 5. The internal electrodes 5 are fixed by being sandwiched between the dielectric layers, but the surface electrodes 14 themselves adhere to the first and second surfaces of the laminate by taking advantage of the phenomenon of solid solution of the ceramic component in the main surfaces.

[0018] The surface electrode 14 and the internal electrode 5 each may contain a glass component, and the amount of glass component in the surface electrode 14 may be greater than the amount of glass component in the internal electrode 5 .

[0019] Furthermore, by making the surface electrode 14 thicker than the internal electrode 5, the conductivity of the surface electrode 14, which contains more ceramic and glass components than the internal electrode 5, can be maintained at least equal to that of the internal electrode 5. The thickness of the surface electrode 14 must be at least greater than the value obtained by multiplying it by the reciprocal of the volume content of the metal component in the surface electrode 14, but in reality this varies greatly depending on the spatial structure of the metal component and other components, so the thickness may be three times that or more.

[0020] As shown in the cross-sectional view of Figure 4C, via array capacitor 23 has multiple surface electrodes 14 of different polarities arranged in an alternating array on the first and second surfaces, and is connected to internal electrodes 5 that form the capacitor inside by through conductors 20. The outer edges and corners E1 of the flat rectangular plate are chamfered by barrel polishing, sandblasting, etc. Chamfering leaves chamfered surfaces E2, which reduces the occurrence of chipping and microcracks that are inherent to ceramics and facilitates product handling in parts feeders, etc.

[0021] In an embodiment of the manufacturing method for the first embodiment of the multilayer ceramic electronic component, the method includes the steps of alternately stacking a plurality of ceramic green sheets 10 and a plurality of internal electrodes 5 including through conductors 20 to form a laminate, obtaining a base laminate 11 (see Figure 3) having surface electrodes 14 laid on at least one of the first and second surfaces of the laminate and a resin layer 15 protecting the surface electrodes 14, cutting the base laminate 11 along planned cutting lines 12 perpendicular to the base laminate 11 to obtain a rectangular element precursor 13, removing the resin layer 15 from the element precursor 13 by firing, and chamfering the edges of the element precursor 13 before firing.

[0022] The resin layer 15 is made of a resin sheet 16, and the resin sheet 16 is laminated on at least one of the first and second surfaces of the laminate together with the surface electrode 14 when the ceramic green sheets are laminated.

[0023] Barrel polishing, the mainstream method for chamfering ceramic chip components, is a simple process that allows for chamfering with high production efficiency. However, because it polishes not only the corners and ridges but also the surface of the element component 2, conventionally, the attachment of surface electrodes 14 has been performed after chamfering. Therefore, the smaller the component, the more difficult it is to maintain the accuracy of the attachment position of the external electrodes 3 (see Figures 5A and 5B) on the first and second surfaces. Below, we will explain in detail the process of providing surface electrodes 14 on the base laminate 11 before it is cut into individual element components 2, and then chamfering the surface electrodes 14 without damaging them.

[0024] First, a ceramic powder mixture of BaTiO3, a ceramic dielectric material, and additives is wet-pulverized and mixed in a bead mill. A polyvinyl butyral binder, a plasticizer, and an organic solvent are added to this pulverized and mixed slurry to produce a ceramic slurry.

[0025] Next, ceramic green sheets 10a to 10e (the suffixes a to e are omitted when referring to them collectively) are formed on a carrier film using a die coater. The thickness of the ceramic green sheets 10 may be, for example, about 1 to 10 μm. The thinner the ceramic green sheets 10, the higher the capacitance of the multilayer ceramic capacitor can be. The formation of the ceramic green sheets 10 is not limited to a die coater, and may also be performed using, for example, a doctor blade coater or a gravure coater.

[0026] In addition, a resin sheet 16 is separately prepared. The thickness of the resin sheet 16 may be, for example, approximately 10 to 50 μm. The resin sheet 16 functions as a protective layer during barrel polishing, so if it is too thin, it will not function during barrel polishing. Furthermore, if it is too thick, the material cost will increase. The resin sheet 16 is attached to the surface of the laminate formed by the ceramic green sheet 10 and the internal electrodes 5 and serves as a protective layer as shown in FIG. 4B, but is burned away in the subsequent firing process as shown in FIG. 4C. The resin sheet 16 is a thermoplastic resin such as polyethylene, polypropylene, polystyrene, acrylonitrile styrene, methacrylic resin, polyethylene terephthalate, polyvinyl alcohol, polyurethane resin, polyethylene oxide resin, and methacrylic acid ester polymer.

[0027] The glass transition temperature of the resin in the resin sheet 16 varies significantly depending on the molecular weight and acetyl group content of the resin, even for the same type of resin. Selecting a resin with a glass transition temperature close to that of the overall resin, including the binder and plasticizer contained in the ceramic green sheet 10, results in a resin layer 15 made of the resin sheet 16 with similar thermoplasticity to that of the ceramic green sheet 10, resulting in a laminate with less internal strain during the subsequent lamination press process. Furthermore, if the thermal decomposition temperature of the resin is equal to or lower than that of the binder contained in the ceramic green sheet 10 and the internal electrode 5, the effect on the firing profile during the subsequent firing process of the element precursor 13 is reduced. Furthermore, the resin layer 15 may be a resin that does not contain chlorine or fluorine. Such a resin reduces the risk of substances such as chlorine or fluorine remaining on the surface of the element component 2 after firing of the element precursor 13, which could cause degradation of the product's properties due to chlorine or fluorine.

[0028] Next, ceramic green sheets 10 with through holes are prepared. The positions where the through holes are formed are the central positions indicated by the through conductors 20 in FIG. 2. FIG. 2 is a schematic diagram corresponding to a single element component, but at this stage of drilling, the holes are drilled in each ceramic green sheet 10 before the base laminate 11 is cut into element precursors 13 of the individual element components 2. The diameter of the through holes may be approximately 30 to 1500 μm, and the holes may be drilled using a drill, a punch, or laser processing.

[0029] Next, the ceramic green sheet 10 with the through holes created above may be formed by printing conductive paste for the internal electrode 5 and the surface electrode 14 in a predetermined pattern on each of the base ceramic green sheet 10 and the resin sheet 16.

[0030] The conductive paste is printed using, for example, screen printing or gravure printing. The conductive paste may contain, for example, metals such as Ni, Pd, Cu, Ag, etc., or alloys thereof. The conductive paste for the surface electrode 14 may contain ceramic powder or glass powder in addition to the metal powders described above to improve bonding with the ceramic body during firing. The conductive paste may be, for example, a nickel paste containing nickel powder as the main component and barium titanate powder as a common material.

[0031] The printed pattern of the conductive paste that will become the internal electrodes 5 and surface electrodes 14 will be outlined with reference to the exploded perspective view of FIG. 2, which illustrates the laminated state of one component. The conductive paste for the surface electrodes 14 is printed on the ceramic green sheet 10a. The ceramic green sheet 10b has multiple through holes that are filled with the conductive paste. The internal electrodes 5 for two types of polarity are printed on the ceramic green sheets 10c and 10d. At the same time, the internal electrodes 5 are embedded in the through holes. The conductive paste for the surface electrodes 14 is printed on the resin sheet 16.

[0032] The thinner the thickness of the internal electrode 5, the more it is possible to reduce internal defects caused by internal stress. In the case of a capacitor with a high number of layers, the thickness of the internal electrode 5 may be, for example, 1.0 μm or less.

[0033] After the printing process of the internal electrodes 5, the ceramic green sheets 10 printed with the conductive paste are stacked in the order shown in FIG. 2. First, a predetermined number of blank ceramic green sheets 10e that serve as cover layers are stacked, followed by a predetermined number of ceramic green sheets 10c and 10d on which internal electrodes 5 for two types of polarity are printed, stacked alternately. A predetermined number of ceramic green sheets 10b on which through conductors 20 are printed are then stacked, followed by ceramic green sheets 10a on which surface electrodes 14 are printed, and finally a blank resin sheet 16 is placed on top. These ceramic green sheets 10 are stacked on a support sheet 18. The support sheet 18 may be a weak adhesive sheet or a foam release sheet that can be adhered and released.

[0034] FIG. 3 is a perspective view showing a base laminate 11 formed by pressing the aforementioned laminates together in the stacking direction. The resin layer 15 is translucent, allowing the surface electrodes 14 on the main surface to be seen through. Inside the base laminate 11, the conductive paste previously embedded in the through holes of the ceramic green sheets 10 is connected to form through conductors 20 connecting the internal electrodes 5 and the surface electrodes 14. A support sheet 18 used when stacking the ceramic green sheets 10 is located below the base laminate 11. The imaginary lines drawn in a grid pattern on the main surface of FIG. 3 are intended cutting lines 12 indicating the cutting positions, and the imaginary lines drawn on the side surfaces parallel to the main surface indicate the boundaries between the resin layer 15 and the ceramic layers.

[0035] 4A to 4C, the through conductors 20 can be formed by producing a base laminate 11 by laminating ceramic green sheets 10, and then filling through holes formed by drilling, punching, or laser drilling with a conductive paste, or by laying a resin sheet 16 on the surface. Furthermore, the surface electrodes 14 may be provided on both the first and second surfaces depending on the component performance, and in that case, resin sheets 16 are attached to both the first and second surfaces. The resin sheets 16 may be attached to the first and second surfaces by pressure bonding using a hot press.

[0036] Thereafter, the base laminate 11 is cut along the planned cutting lines 12 to separate it into individual element precursors 13. Fig. 4A is a cross-sectional view of the cut element precursor 13 at a position passing through the center of the through conductor 20. The through conductor 20 connects the internal electrodes 5 and surface electrodes 14 of the same polarity. In addition, a surface resin layer 15 protects the surface electrodes 14.

[0037] Next, the element precursor 13 in Figure 4A is chamfered in a barreling process. The barreling is performed using a wet barreling process in which multiple element precursors 13 before firing are placed in a rotating pot together with an abrasive such as ceramic powder or resin beads and polished in water. For element precursors 13 that do not tolerate water, chamfering may be performed using a dry barreling process that does not use water.

[0038] FIG. 4B is a cross-sectional view of the element precursor 13 after barrel polishing. All edges and apex angles are rounded. Although not clearly shown, the surface has also been polished, and a certain amount of the surface layer on six sides has been removed. On the other hand, the first and second sides have a protective layer of resin layer 15, so the surface electrodes 14 remain in their original state. Focusing on the four sides of each side of the ceramic green sheet 10 that contact the resin layer 15, they have been chamfered to the extent that there are no burrs or corners, as indicated by reference symbol E1.

[0039] Next, in the firing step, the chamfered element precursor 13 is degreased and fired. The element precursor 13 is degreased by heating it to 700°C in a nitrogen atmosphere furnace, and then fired in a hydrogen atmosphere reduction furnace at a peak temperature of 1100 to 1250°C to obtain a sintered element part 2.

[0040] 4C is a cross-sectional view of the element part 2 after firing. The resin layer 15 of the element precursor 13 is burned away during the firing process, leaving the element part 2 consisting of only the ceramic portion after sintering. The four sides of the first and second surfaces of the element part 2 have been chamfered to a certain degree by barrel processing performed before firing, and burrs and sharp corners have been removed, as indicated by reference symbol E2.

[0041] To facilitate solder mounting, the surface electrodes 14 of the fired element component 2 may be plated with a single layer or multiple layers. The method may further include a protrusion-forming plating step for forming protruding conductors on the surface electrodes 14 on which the plating layers have been formed.

[0042] As described above, in the first embodiment, the chamfering process is performed on the base laminate 11 before firing, with the pre-placed surface electrodes 14 protected by the resin layer 15, which makes it possible to form finer surface electrodes 14 with higher precision than with conventional techniques in which surface electrodes 14 are attached to individual element components 2 after firing. Furthermore, because the conventional barrel process can be used for chamfering and the subsequent process of attaching surface electrodes 14 to individual element components 2 is eliminated, the number of manufacturing steps is reduced, enabling cheaper manufacturing.

[0043] (Second embodiment) The second embodiment will be described below. The same reference numerals are used to designate parts corresponding to those in the first embodiment. FIG. 5A is a perspective view of a typical multilayer ceramic capacitor 1a, and FIG. 5B is a perspective view of a multilayer ceramic capacitor 1b, which is called a three-terminal capacitor. Both capacitors have a roughly rectangular parallelepiped element component 2 and external electrodes 3. The external electrodes 3, which are connected to partially exposed internal electrodes 5, are disposed on a pair of end faces 8 or side faces 9 of the element component 2 and extend around to other adjacent surfaces.

[0044] The external electrode 3 generally has a base electrode and a plated outer layer, and is manufactured by applying a conductive paste to the base component 2, then performing a metallization process in which the paste is baked at high temperature to form the base electrode, and then attaching the plated outer layer on top of that. However, as components become smaller, the thickness of the external electrode 3 has become thinner, and products are also known in which the metallized base electrode is omitted and the base component 2 is plated directly to form the external electrode 3.

[0045] 6A and 6B are perspective views showing the element component 2 of each of FIGS. 5A and 5B when the external electrode 3 is formed by direct plating. Surface electrodes 14 are provided on the first and second surfaces 7A and 7B of the element component 2, and portions of the internal electrodes 5 are exposed on the first and second surfaces 7A and 7B or on the side surfaces 9. When plating is performed on such an element component 2, the plating grows from the exposed portions of the internal electrodes 5 on the end surfaces 8 or side surfaces 9 as nuclei, and adjacent portions bond together to form a plating film. This also bonds with the plating film formed on the surface electrodes 14 to form a continuous plating film, making it possible to manufacture a product having external electrodes 3 similar to those shown in FIGS. 5A and 5B.

[0046] The surface electrode 14 is thicker than the internal electrodes 5, and is positioned continuously with a uniform thickness along at least one of the first surface 7A and the second surface 7B of the laminate.

[0047] The surface electrode 14 and the internal electrode 5 each contain a ceramic component, and the amount of ceramic component in the surface electrode 14 may be greater than the amount of ceramic component in each internal electrode 5. The internal electrode 5 is fixed by being sandwiched between the dielectric layers, but the surface electrode 14 is fixed to the first surface 7A and the second surface 7B by itself, taking advantage of the phenomenon in which the ceramic component dissolves in the first surface 7A and the second surface 7B.

[0048] Furthermore, the surface electrode 14 and the internal electrode 5 each may contain a glass component, and the amount of glass component in the surface electrode 14 may be greater than the amount of glass component in the internal electrode 5. The internal electrode 5 is fixed by being sandwiched between dielectric layers, but the surface electrode 14 is fixed to the main surface by itself, taking advantage of the phenomenon in which the glass component dissolves in the main surface.

[0049] By making the surface electrode 14 thicker than the internal electrode 5, the conductivity of the surface electrode 14, which contains more ceramic and glass components than the internal electrode 5, can be maintained at least equal to that of the internal electrode 5. The thickness of the surface electrode 14 must be at least greater than the value obtained by multiplying it by the reciprocal of the volume content of the metal component in the surface electrode 14, but since this actually varies greatly depending on the spatial structure of the metal component and other components, the thickness may be three times that or more.

[0050] The internal electrode 5 located closest to the resin layer 15 of the base laminate 11 is an anchor tab 22, and the exposed portion of the anchor tab 22 on the side surface, the exposed portion of the other internal electrodes 5, and the end of the surface electrode 14 are aligned in the stacking direction. The surface electrode 14 protected by the resin layer 15 of the element precursor 13 has a predetermined electrode pattern and includes an external electrode 3 that connects the internal electrode 5 and the electrode pattern of the surface electrode 14.

[0051] In an embodiment of the manufacturing method for the multilayer ceramic capacitor 1a of the second embodiment, the method includes the steps of alternately stacking a plurality of ceramic green sheets 10 and a plurality of internal electrodes 5 to form a laminate, obtaining a base laminate 11 having surface electrodes 14 laid on at least one of the first and second surfaces of the laminate and a resin layer 15 protecting the surface electrodes 14, cutting the base laminate 11 along planned cutting lines 12 perpendicular to the base laminate 11 to obtain a rectangular element precursor 13, removing the resin layer 15 from the element precursor 13 by firing, and chamfering the edges of the element precursor 13 before firing.

[0052] The resin layer 15 is made of a resin sheet 16, which is laminated on at least one of the first surface 7A and the second surface 7B of the laminate together with a surface electrode 14 when laminating the ceramic green sheets 10. The surface electrode 14 may also be provided on the resin sheet 16.

[0053] In the second embodiment below, a manufacturing method thereof will be described using the base part 2 of FIG. 6A as an example.

[0054] First, a raw material slurry is prepared and formed into a ceramic green sheet 10. The preparation of the ceramic green sheet 10 is similar to that of the first embodiment, so a redundant explanation will be omitted, but the thickness of the ceramic green sheet 10 is desirably 10 μm or less. When the external electrodes 3 are formed directly on the element component 2 by plating, the plating grows from the layer edges of the internal electrodes 5 exposed on the side surfaces 9 of the element component 2 as nuclei, and forms a plating film that combines with the plating that grows at the layer edges of adjacent internal electrodes 5. Therefore, if the spacing between the internal electrodes 5 is 10 μm or more, the continuity of the plating film may be impaired.

[0055] Meanwhile, conductive pastes for the internal electrodes 5 and the surface electrodes 14 are prepared. The details are the same as those in the first embodiment, so a duplicated explanation will be omitted. The conductive paste for the anchor tabs 22 (see FIG. 7) used in the second embodiment may contain metals such as Ni, Pd, Cu, Ag, etc., or alloys thereof. It may also be the same conductive paste as that for the internal electrodes 5. These conductive pastes are printed in a predetermined pattern on the ceramic green sheets 10 by a printing method such as screen printing or gravure printing.

[0056] Separately, a resin sheet 16 is prepared. The thickness of the resin sheet 16 may be, for example, about 10 to 100 μm. The material and properties of the resin sheet 16 are as described above in the first embodiment. The resin sheet 16 is used to protect the electrodes on the first and second surfaces of the element part 2 from damage and adhesion of foreign matter during the chamfering process.

[0057] A pattern of surface electrodes 14 is printed with conductive paste on some of the resin sheets 16. When the surface electrodes 14 printed on the resin sheets 16 are pressed against the ceramic green sheets 10 after lamination and compression bonding, and then fired as is, the resin sheets 16 are burned away and become the surface electrodes 14 of the element component 2, which is a fired ceramic body.

[0058] 7 is an exploded perspective view showing a schematic diagram of a stack of ceramic green sheets 10 printed with internal electrodes 5, corresponding to a single component. A resin sheet 16 with surface electrodes 14 printed thereon is placed on a support sheet 18 (see FIG. 8). A predetermined number of ceramic green sheets 10 with anchor tabs 22 printed thereon are then stacked in the following order: a predetermined number of alternating ceramic green sheets 10 with two types of internal electrodes 5, a predetermined number of ceramic green sheets 10 with anchor tabs 22 printed thereon, and a ceramic green sheet 10 with surface electrodes 14 printed thereon. Finally, a blank resin sheet 16 is placed on top. The support sheet 18 may be a weak adhesive sheet or a release adhesive sheet, such as a foam release sheet, that can be adhered and released.

[0059] Next, the laminate is pressed in a pressing process to obtain an integrated base laminate 11 as shown in FIG. 8. The base laminate 11 can be pressed using, for example, an isostatic press. Heating may be applied during pressing to accelerate adhesion of the ceramic green sheets 10. The imaginary line 12 shown in FIG. 8 is a planned cutting line indicating the cutting position. A support sheet 18 used when stacking the ceramic green sheets 10 is located below the base laminate 11.

[0060] Next, the base laminate 11 is cut to a predetermined size along the planned cutting lines 12 using a pressure cutting device to obtain the element precursor 13 shown in Figure 9. The method for cutting the base laminate 11 is not limited to using a pressure cutting device, and a dicing saw device, for example, may also be used. The first and second surfaces, end faces, and side faces of the base laminate 11 correspond to the first and second surfaces 7A and 7B, end faces 8, and side faces 9 of the element precursor 13, respectively, and therefore will be denoted by the same reference numerals hereinafter.

[0061] In Figure 9, the surface electrodes 14 are visible because the resin layer 15 is a semi-transparent layer, but the surface electrodes 14 are protected by the resin layer 15. Furthermore, the internal electrodes 5 and anchor tabs 22 shown in Figure 7, and parts of the surface electrodes 14, are exposed in the same row on the end faces 8 and side faces 9. Since the external electrodes 3 are formed by direct plating, the areas where they are arranged in the same row are the areas where the external electrodes 3 are formed.

[0062] Fig. 10A is a cross-sectional view of the element precursor 13 in the AA' plane of Fig. 9. The surface electrodes 14 are protected by the resin layers 15 on the first and second surfaces.

[0063] Next, chamfering is performed in the barreling process. The barreling is performed using a wet barrel, in which multiple element precursors 13 are placed in a rotating pot together with an abrasive such as ceramic powder or resin beads, or a lubricant, and polished in water. For element parts that do not tolerate water, chamfering can also be performed using a dry barrel, which does not use water.

[0064] FIG. 10B is a cross-sectional view of the element precursor 13 after barrel polishing. All edges and apex angles are rounded, as indicated by reference symbol E3. Although not clearly shown, all surfaces have been polished, and a certain amount of the surface layer on each of the six surfaces has been removed. On the other hand, the first surface 7A and the second surface 7B have the protective resin layer 15, so the surface electrode 14 remains intact. Focusing on the four sides where the ceramic green sheets 10 are stacked and in contact with the resin layer 15, these areas have also been chamfered to the extent that there are no burrs or sharp edges.

[0065] Next, the chamfered base part 2 is degreased and fired in a firing process. Degreasing is performed in a nitrogen atmosphere furnace by raising the temperature to 700°C, and then firing is performed in a hydrogen atmosphere reduction furnace at a peak temperature of 1100 to 1250°C, and the base part 2 is sintered.

[0066] 10C is a perspective view of the element part 2 after firing. The resin layer 15 of the element precursor 13 is burned away during the firing process, leaving the element part 2 consisting of only the sintered ceramic portion. The four sides of the first surface 7A and the second surface 7B are also chamfered to a certain level, as indicated by reference symbol E4, by barrel processing performed before firing.

[0067] Finally, the fired element component 2 is subjected to electroless plating or electrolytic plating to form external electrodes 3 composed of plating films. The plating grows from the exposed ends of the internal electrodes 5 on the end faces 8 or side faces 9 as nuclei, and adjacent portions bond together to form plating films, which also bond with the plating film formed on the surface electrodes 14 to form a continuous plating film. The plating may be a copper plating layer. After plating, annealing may be performed at a high temperature of 600°C to 800°C to form an alloy at the joint with the internal electrodes 5, which is mainly composed of Ni, thereby increasing the bonding strength.

[0068] Furthermore, to facilitate solder mounting, the multi-layered outer plating layer may be formed by superposing a Ni layer, a Sn layer, etc. Through the above steps, a multilayer ceramic capacitor 1a as shown in Fig. 5A is completed.

[0069] As described above, in the second embodiment, there is no need to prepare ceramic green sheets of various thicknesses, and there is no need to apply conductive paste to form the external electrodes 3. This reduces the number of manufacturing steps and enables inexpensive manufacturing. Furthermore, the plating film can be formed thinly and is formed on the exposed portions of the surface electrodes 14 and internal electrodes 5, which do not damage the shape of the underlying film, allowing for miniaturization and high precision of components. This facilitates the manufacture of capacitors that require a narrow pitch, such as the three-terminal capacitor 1b shown in FIG. 5B or an even more expanded multi-terminal capacitor.

[0070] The multilayer ceramic capacitor according to the present disclosure can have the following embodiments (1) to (3).

[0071] (1) a laminate in which dielectric layers and internal electrodes are alternately stacked; a surface electrode provided on at least one of a first surface and a second surface of the laminate; an external electrode connecting the surface electrode and the internal electrode; A multilayer ceramic electronic component in which the thickness of the surface electrodes is greater than the thickness of the internal electrodes, and the surface electrodes are positioned continuously with a uniform thickness along at least one of the first surface and the second surface of the laminate.

[0072] (2) the surface electrodes and the internal electrodes each contain a ceramic component; The multilayer ceramic electronic component according to (1) above, wherein the ceramic content of the surface electrodes is greater than the ceramic content of each of the internal electrodes.

[0073] (3) the surface electrodes and the internal electrodes each contain a glass component; The multilayer ceramic electronic component according to (1) above, wherein the surface electrodes have a larger glass component content than the internal electrodes.

[0074] The method for manufacturing a multilayer ceramic capacitor according to the present disclosure can be embodied in the following embodiments (4) to (8).

[0075] (4) a step of alternately stacking a plurality of ceramic green sheets and a plurality of internal electrodes to obtain a laminate; obtaining a base laminate having a surface electrode and a resin layer protecting the surface electrode on at least one of a first surface and a second surface of the laminate; cutting the base laminate along cutting lines perpendicular to the base laminate to obtain a rectangular element precursor; removing the resin layer of the element precursor by baking; and chamfering edges of the element precursor before firing.

[0076] (5) The method for producing a multilayer ceramic electronic component according to (4), wherein the resin layer is made of a resin sheet, and the resin sheet is laminated on at least one of the first surface and the second surface of the laminate together with the surface electrode when laminating the ceramic green sheets.

[0077] (6) The method for producing a multilayer ceramic electronic component according to (5) above, wherein the surface electrodes are provided on the resin sheet.

[0078] (7) The method for producing a multilayer ceramic electronic component according to any one of (4) to (6) above, wherein the internal electrode located closest to the resin layer is an anchor tab, and an exposed portion of the anchor tab on a side surface, an exposed portion of another internal electrode, and an end portion of a surface electrode are aligned in the stacking direction.

[0079] (8) The surface electrodes protected by the resin layer of the element precursor have a predetermined electrode pattern, The method for producing a multilayer ceramic electronic component according to (4) above, further comprising the step of connecting the internal electrodes and the electrode patterns with external electrodes.

[0080] According to the multilayer ceramic electronic component and the manufacturing method thereof disclosed herein, which are configured as described above, the electrodes formed on the main surfaces of the base laminate before being cut into the individual components can be chamfered after cutting into the individual components without damaging them, and therefore it is possible to provide a small-sized multilayer ceramic electronic component having highly accurate surface electrodes.

[0081] The present disclosure can be implemented in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely examples in all respects, and the scope of the present disclosure is defined by the claims and is not limited by the text of the specification. Furthermore, all modifications and variations that fall within the scope of the claims are within the scope of the present disclosure. [Explanation of symbols]

[0082] 1. Multilayer ceramic capacitors 2 Base parts 3 External electrode 4. Dielectric ceramic 5 Internal electrode 6 Protective layer 7A 1st page 7B 2nd side 8 End face 9 Side 10 Ceramic green sheet 11 Mother laminate 12 Cutting line 13. Prime Body Precursor 14 Surface electrode 15 Resin layer 16 Resin sheet 17 Plating growth origin 18 Support Sheet 20 Through conductor 22 Anchor Tab 23 Via array capacitor 1b Three-terminal capacitor

Claims

1. a step of alternately stacking a plurality of ceramic green sheets and a plurality of internal electrodes to obtain a laminate; obtaining a base laminate having a surface electrode and a resin layer protecting the surface electrode on at least one of a first surface and a second surface of the laminate; cutting the base laminate along cutting lines perpendicular to the base laminate to obtain a rectangular element precursor; removing the resin layer of the element precursor by baking; and chamfering edges of the element precursor before firing.

2. 2. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the resin layer is made of a resin sheet, and the resin sheet is laminated on at least one of the first surface and the second surface of the laminate together with the surface electrode when the ceramic green sheets are laminated.

3. 3. The method for manufacturing a multilayer ceramic electronic component according to claim 2, wherein the surface electrodes are provided on the resin sheet.

4. 4. The method for manufacturing a multilayer ceramic electronic component according to claim 1, wherein the internal electrode located closest to the resin layer is an anchor tab, and an exposed portion of the anchor tab on a side surface, an exposed portion of another internal electrode, and an end of a surface electrode are aligned in the stacking direction.

5. the surface electrodes protected by the resin layer of the element precursor have a predetermined electrode pattern; 2. The method for manufacturing a multilayer ceramic electronic component according to claim 1, further comprising the step of connecting said internal electrodes and said electrode patterns with external electrodes.

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