Multilayer ceramic capacitor and circuit board

Abstract

To provide a multilayer ceramic capacitor in which the amount of static electricity generated during handling is suppressed, and to provide a circuit board on which the multilayer ceramic capacitor is mounted.SOLUTION: The multilayer ceramic capacitor 100 includes a rectangular parallelepiped element body 40 including a multilayer body in which ceramic layers and internal electrodes containing a metal as a main component are alternately stacked, a pair of covers disposed at both ends of the multilayer body in a stacking direction and covering a surface of the multilayer body, and a margin covering at least a part of an end of the ceramic layer and at least a part of an end of the internal electrode in the multilayer body and connecting the pair of covers to each other. A plurality of terminal electrodes 40 electrically connected to the internal electrodes are provided, and particles 50 of a metal oxide different from a material forming an exposed portion are adhered to the exposed portion of at least one of main surfaces having the largest area among surfaces forming the surface of the element body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multilayer ceramic capacitor and a circuit board. [Background technology]

[0002] A wide variety of ceramic electronic components are used in high-frequency communication systems, such as mobile phones. These ceramic electronic components are required to be smaller and thinner, and efforts are being made to make them smaller and thinner in multilayer ceramic capacitors as well.

[0003] Patent Document 1 discloses a thin, break-resistant multilayer ceramic capacitor in which via-hole electrodes that electrically connect internal electrode layers to each other and internal electrode layers to terminal electrodes have voids formed therein. In the multilayer ceramic capacitor disclosed in Patent Document 1, terminal electrodes are formed on the flat upper surface of the element body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-72263 Summary of the Invention [Problem to be solved by the invention]

[0005] The multilayer ceramic capacitor disclosed in Patent Document 1 has smooth, opposing top and bottom surfaces of the element body. Therefore, when handling singulated capacitor chips during the manufacturing process, the exposed top and bottom surfaces of the element body, not covered by terminal electrodes, come into contact with manufacturing equipment, jigs, other capacitor chips, etc., resulting in an increased contact area and an increased amount of static electricity. This increases the likelihood of transport problems due to sticking, resulting in reduced manufacturing yields. Furthermore, the increased static electricity caused by the smooth top and bottom surfaces of the element body also occurs when the cover tape is peeled off from the carrier tape containing the capacitors. This increased static electricity also causes the capacitor chips to stick to the peeled cover tape, resulting in reduced assembly yields.

[0006] The present invention has been made to solve the above problems, and has an object to provide a multilayer ceramic capacitor in which the amount of static electricity generated during handling is reduced, and a circuit board on which the multilayer ceramic capacitor is mounted. [Means for solving the problem]

[0007] The inventors have conducted various studies to solve the above-mentioned problems and have found that the above-mentioned object can be achieved by attaching particles of a metal oxide different from the constituent materials of the upper and lower surfaces to at least one of the exposed upper and lower surfaces of the element body of a multilayer ceramic capacitor, thereby completing the present invention.

[0008] That is, a first aspect of the present invention for solving the above-mentioned problems is a multilayer ceramic capacitor comprising: a laminate in which ceramic layers and internal electrodes mainly composed of metal are alternately stacked; a rectangular parallelepiped element body having a pair of cover portions arranged at both ends of the laminate in the stacking direction and covering the surface of the laminate; and margin portions covering at least a portion of the ends of the ceramic layers and the ends of the internal electrodes in the laminate and connecting the pair of cover portions; and a plurality of terminal electrodes arranged at least on a mounting surface that faces a circuit board when mounted on the circuit board, among the surfaces that form the surface of the element body, and electrically connected to the internal electrodes, wherein at least one of the main surfaces that has the largest area among the surfaces that form the surface of the element body has particles of a metal oxide adhered to its exposed portion, the metal oxide being different from the material that forms the exposed portion.

[0009] A second aspect of the present invention for solving the above problem is a circuit board on which the multilayer ceramic capacitor according to the first aspect is mounted. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a multilayer ceramic capacitor in which the amount of static electricity generated during handling is reduced, and a circuit board on which the multilayer ceramic capacitor is mounted. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic view (perspective view) showing the structure of a multilayer ceramic capacitor according to a first embodiment of the present invention. [Figure 2] 2 is a cross-sectional view taken along line AA (LT cross-sectional view) in FIG. 1. [Figure 3] FIG. 1 is a schematic diagram showing a procedure for dividing a mapping image of metal elements for an exposed portion of the main surface of an element body into square cells each 20 μm on a side. [Figure 4] FIG. 1 is a schematic diagram (LT cross section) showing the structure of a multilayer ceramic capacitor in which metal oxide particles adhere only to the mounting surface. [Figure 5]FIG. 4 is a schematic view (LT cross-sectional view) showing the structure of a multilayer ceramic capacitor according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a schematic view (perspective view) showing the structure of a multilayer ceramic capacitor according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] The configuration and effects of the present invention will be described below, along with the technical concept, with reference to the drawings. However, the mechanism of action includes assumptions, and the correctness of such assumptions does not limit the present invention.

[0013] [Multilayer ceramic capacitors] First Embodiment An embodiment of a multilayer ceramic capacitor according to a first aspect of the present invention is shown in FIGS. 1 and 2 as a first embodiment. The multilayer ceramic capacitor 100 according to the first embodiment has a rectangular parallelepiped shape and includes a pair of faces perpendicular to each of three mutually orthogonal axes, i.e., the L-axis, which is the length direction, the W-axis, which is the width direction, and the T-axis, which is the height direction. The rectangular parallelepiped is not limited to a mathematically defined rectangular parallelepiped, and may have any shape that is recognized as a rectangular parallelepiped when observed as a whole. Therefore, a rectangular parallelepiped in the present disclosure also includes a capacitor with slightly rounded edges or corners, a capacitor with slightly curved edges, and a capacitor with curved faces with a small curvature. The length (L), width (W), and height (T) dimensions of the ceramic capacitor 100 can each independently take any value.

[0014] The dimensions of the multilayer ceramic capacitor 100 are, for example, an L-direction dimension of 200 μm to 2000 μm, a W-direction dimension of 100 μm to 2000 μm, and a T-direction dimension of 30 μm to 220 μm, with a value W / L (the ratio of the W-direction dimension to the L-direction dimension) of 0.3 to 1.0. It is preferable that the L-direction dimension be 400 μm to 1200 μm, the W-direction dimension be 400 μm to 1200 μm, and the T-direction dimension be 40 μm to 150 μm, with a value W / L (the ratio of the W-direction dimension to the L-direction dimension) of 0.4 to 1.0. It is more preferable that the T-direction dimension be 100 μm or less, as this is less subject to design constraints on the circuit board on which it is mounted.

[0015] 2, the multilayer ceramic capacitor 100 according to the first embodiment includes an element body 10 having a laminate 20 in which ceramic layers 21 and internal electrodes 22 mainly composed of metal are alternately stacked in the T direction, a pair of cover portions 31 disposed at both ends of the laminate 20 in the stacking direction and covering the surface of the laminate 20, and margin portions 32 covering at least a portion of the ends of the ceramic layers 21 and the internal electrodes 22 in the laminate 20 and connecting the pair of cover portions 31 to each other. The internal electrodes 22 include internal electrodes 22a of one polarity that are electrically connected to each other, and internal electrodes 22b of a polarity different from that of the internal electrodes 22a that are electrically connected to each other.

[0016] There is no particular limitation on the method for electrically connecting the internal electrodes 22a to each other and the internal electrodes 22b to each other. Fig. 2 shows a mode in which the internal electrodes are connected by via conductors 23 (23a, 23b) that are arranged inside the element body 10 so as to penetrate the ceramic layers 21 in the stacking direction of the laminate 20 and have at least one end reaching the surface of a cover portion 31, which will be described later. However, as in a second embodiment, which will be described later, the internal electrodes may be extended to the end faces of the element body and connected by external conductors. Note that although the multilayer ceramic capacitor 100 shown in Fig. 2 has two via conductors 23, the number of via conductors in the multilayer ceramic capacitor according to the first aspect of the present invention is not limited to this.

[0017] On the surface of the element body 10, a cover portion 31 is arranged on a surface perpendicular to the T direction of the laminate 20, and margin portions 32 are arranged on surfaces perpendicular to the W direction and the L direction of the laminate. When the internal electrodes are drawn out to the end faces of the element body as in the second embodiment described later, no margin portions are arranged on the end faces (drawing faces) from which the internal electrodes are drawn out.

[0018] The multilayer ceramic capacitor 100 according to the first embodiment includes a plurality of terminal electrodes 40 (40a, 40b) disposed at least on a mounting surface 11, which is the surface that faces the circuit board when mounted on the circuit board, among the surfaces that form the surface of the element body 10. The terminal electrodes 40 (40a, 40b) are electrically connected to internal electrodes 22 (22a, 22b). The method for electrically connecting the terminal electrodes 40 (40a, 40b) to the internal electrodes 22 (22a, 22b) is not particularly limited. FIG. 2 shows a mode in which the terminal electrodes 40 are connected via via conductors 23 (23a, 23b), but they may also be connected via external conductors, as in a second embodiment described later. Note that although the multilayer ceramic capacitor 100 shown in FIG. 2 includes two terminal electrodes 40, the number of terminal electrodes in the multilayer ceramic capacitor according to the first aspect of the present invention is not limited to this.

[0019] In the multilayer ceramic capacitor 100 according to the first embodiment, metal oxide particles 50 different from the material forming the exposed portions are adhered to an exposed portion of at least one of the principal surfaces that has the largest area among the surfaces forming the surface of the element body 10, i.e., a portion that is not covered by the terminal electrodes 40 (40a, 40b) or an external conductor, which will be described later. Note that the multilayer ceramic capacitor 100 shown in Fig. 2 has two opposing principal surfaces of the element body 10 that are the mounting surface 11 and the opposing surface 12, and has metal oxide particles 50 adhered to both principal surfaces, but the multilayer ceramic capacitor according to the first embodiment of the present invention may have a principal surface other than the mounting surface and the opposing surface, or may have metal oxide particles adhered to only one principal surface.

[0020] The thickness of the element body 10, obtained by subtracting the thickness of the terminal electrodes 40 (40a, 40b) from the T-direction dimension of the multilayer ceramic capacitor 100 described above, is, for example, 20 μm to 200 μm, and preferably 30 μm to 180 μm.

[0021] Hereinafter, each component constituting the multilayer ceramic capacitor 100 according to the first embodiment will be described in detail.

[0022] (ceramic layer) The ceramic layer 21 is made of ceramic. The ceramic composition is not particularly limited as long as it forms a dense ceramic layer 21 by co-firing with the internal electrodes 22 described later, and may be appropriately selected depending on the properties required for the multilayer ceramic capacitor. Examples of ceramic compositions include those containing barium titanate (BaTiO3) as the main component, those containing strontium titanate (SrTiO3) as the main component, and those containing BaTiO3 having a perovskite structure. 1-x-y Ca x Sr y Ti 1-z Zr z Examples of such ceramics include those containing O3 as a main component. The ceramic may contain an additive element in addition to the main component. Examples of the additive element include at least one selected from Mo, Nb, Ta, W, Mg, Mn, V, Cr, rare earth elements (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb), and Co, Ni, Li, B, Na, K, and Si. The additive element may be contained as a simple element or in the form of a compound such as an oxide, nitride, or carbide. The additive element may exist in a solid solution state in the main component, or may form a different phase from the elements constituting the main component or other additive elements.

[0023] (internal electrode) The internal electrodes 22 (22a, 22b) are primarily composed of a metal. The type of metal is not particularly limited, and nickel (Ni), copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), and alloys thereof can be used. Among these, nickel (Ni) is preferred as the primary element because of its high heat resistance, which allows the firing temperature to be increased when co-firing with the ceramic layer 21 to form a dense ceramic layer 21, and it is relatively inexpensive. Here, the term "primary element" as used herein refers to the element with the highest content expressed in atomic percentage (atomic %).

[0024] The internal electrodes 22 (22a, 22b) may contain, in addition to metal, ceramic particles having the same composition as the ceramic constituting the ceramic layer 21, or a glass component.

[0025] (Cover and margin) Both the cover portion 31 and the margin portion 32 have the function of protecting the ceramic layer 21 and the internal electrode 22. The material of the cover portion 31 and the margin portion 32 is not limited as long as it has high electrical insulation and low permeability to deterioration factors such as moisture. From the viewpoints of making shrinkage during firing when manufacturing the multilayer ceramic capacitor 100 uniform and alleviating internal stress within the multilayer ceramic capacitor 100, it is preferable that the main component of the cover portion 31 and the margin portion 32 be the same as the ceramic that forms the ceramic layer 21.

[0026] (Via conductor) Like the internal electrodes 22 (22a, 22b), the via conductors 23 (23a, 23b) are primarily composed of metal. Usable metals include those similar to those of the internal electrodes 22 (22a, 22b) described above. The composition of the via conductors may be different from that of the internal electrodes 22 (22a, 22b), but is preferably the same as that of the internal electrodes 22 (22a, 22b). By making the via conductors (23a, 23b) and the internal electrodes 22 (22a, 22b) the same composition, the magnitude of shrinkage caused by firing during manufacturing of the multilayer ceramic capacitor 100 is uniform, suppressing deformation, and the resistivity of the conductive paths of the multilayer ceramic capacitor 100 is uniform, suppressing localized heat generation during use.

[0027] The diameter of the via conductors (23a, 23b) is not particularly limited, but in order to ensure the capacity of the multilayer ceramic capacitor 100 while reducing electrical resistance and suppressing heat generation during circuit operation, it is preferable to make it 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less.

[0028] (terminal electrode) The material of the terminal electrodes 40 (40a, 40b) is not limited as long as it is conductive, and examples of the material include metals such as nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), and gold (Au), alloys containing any of these as a main component, and conductive resins.

[0029] The terminal electrodes 40 (40a, 40b) may have an underlying conductor 41 in contact with the element body 10 and a plated conductor 42 formed on the surface of the underlying conductor 41. The terminal electrodes 40 (40a, 40b) having such a structure can improve adhesion to the element body 10 by the underlying conductor 41, and can improve solder wettability by the plated conductor 42 when mounted on a circuit board.

[0030] Ni is an example of the material of the underlying conductor 41. The thickness of the underlying conductor 41 can be set to 0.1 μm or more and 10 μm or less, and preferably 0.5 μm or more and 5 μm or less.

[0031] The plated conductor 42 may be formed of a single layer or multiple layers. When the plated conductor 42 is formed of multiple layers, the number of layers is preferably two to four. An example of the material and structure of the plated conductor 42 is one formed of Cu, Ni, and Sn in this order. The thickness of the plated conductor 42 can be 1 μm to 20 μm, and preferably 3 μm to 10 μm.

[0032] The area of ​​the terminal electrodes 40 (40a, 40b), i.e., the area of ​​the terminal electrodes 40 (40a, 40b) observed when the multilayer ceramic capacitor 100 is viewed from a direction perpendicular to the mounting surface 11, is not particularly limited, as long as it is large enough to facilitate mounting on a circuit board and small enough to prevent short-circuiting between electrodes having opposite polarities. Preferably, the ratio of the total area of ​​the terminal electrodes 40 to the area of ​​the mounting surface 11 is 0.2 to 0.9, and more preferably, the ratio is 0.3 to 0.8.

[0033] (metal oxide particles) The metal oxide particles 50 adhere to the exposed portions of the main surfaces of the element body 10. This forms protrusions on the exposed portions of the main surfaces, reducing the contact area with other components or elements and thereby reducing the amount of static electricity generated. Here, "adhesion" refers to a state in which the metal oxide particles 50 wet the exposed portions of the main surfaces or penetrate into the element body 10 from the exposed portions. The adhesive strength refers to the strength of the metal oxide particles 50 remaining on the main surfaces even after peeling off a release tape applied to the exposed portions of the main surfaces. Both of these meanings are different from simple contact. The adhesion of the metal oxide particles 50 to the exposed portions of the main surfaces of the element body 10 prevents the metal oxide particles 50 from detaching when the multilayer ceramic capacitor 100 is handled or when a circuit board on which it is mounted is used. This not only maintains the static electricity suppression effect for a long period of time, but also prevents circuit board failures caused by detached metal oxide particles 50.

[0034] The metal oxide particles 50 are formed of a metal oxide different from the material forming the surface to which they adhere, i.e., the exposed portion not covered by the terminal electrodes 40 (40a, 40b) or external conductor, of at least one of the principal surfaces that has the largest area among the surfaces that form the surface of the element body 10. This forms an area with a different surface potential in the exposed portion of the principal surface, thereby suppressing the amount of static electricity generated. Here, the metal oxide different from the material forming the exposed portion of the principal surface means not only an oxide of a metal element different from the metal element contained in the exposed portion, but also a composite oxide that contains a metal element contained in the exposed portion but also contains other metal elements that are not contained in the exposed portion, an oxide that does not contain some of the multiple metal elements contained in the exposed portion, and an oxide that contains the same metal elements as the exposed portion but in a different content ratio of the metal elements.

[0035] Although the type and number of metal elements contained in the metal oxide are not particularly limited, when the terminal electrodes (40a, 40b) have the base conductor 41 and the plated conductor 42 as described above, it is preferable that the metal elements are the same as those contained in the base conductor 41. This improves the adhesion strength between the metal oxide particles 50 and the element body 10, and significantly suppresses the detachment of the metal oxide particles 50 when handling the multilayer ceramic capacitor 100 or when using a circuit board on which it is mounted. In addition, oxides of metal elements commonly contained in the base conductor 41 have high electrical insulation properties, and are therefore preferable in that even if the oxide particles adhere to the exposed portions of the element body 10, the electrical insulation of the surface of the multilayer ceramic capacitor is not likely to deteriorate.

[0036] When the metal oxide is nickel oxide, there is an advantage in that it suppresses deterioration in the characteristics caused by an externally applied magnetic field to the multilayer ceramic capacitor 100. This is presumably because nickel oxide is an antiferromagnetic material that does not have a magnetic moment and therefore does not magnetically respond to an external magnetic field.

[0037] The area density of the metal oxide particles 50 in the exposed portion of the main surface to which the metal oxide particles 50 are adhered is 5×10 -5 pieces / μm2 Over 500 x 10 -4 pieces / μm 2 When the area density is within the above range, the effect of reducing the amount of static electricity becomes significant. The area density is more preferably 1×10 -4 pieces / μm 2 Over 480 x 10 -4 pieces / μm 2 or less, and more preferably 3×10 -4 pieces / μm 2 Over 450 x 10 -4 pieces / μm 2 The following is the result.

[0038] When the area density is within the preferred range described above, when the exposed portion is divided into square cells with sides of 20 μm, the percentage of the number of cells containing metal oxide particles 50 relative to the total number of cells is preferably 20% or more. This means that the metal oxide particles 50 are distributed over a wide area in the exposed portion, which results in a more significant effect of reducing static electricity. The percentage is more preferably 25% or more, and even more preferably 30% or more.

[0039] The particle size of the metal oxide particles 50 is preferably 0.1 μm or more and 10 μm or less. This significantly reduces the amount of static electricity. The particle size is more preferably 0.3 μm or more and 9 μm or less, and even more preferably 0.5 μm or more and 8 μm or less.

[0040] It is preferable that at least one of the metal oxide particles 50 has a protruding height of 0.5 μm or more and 10 μm or less from the main surface to which it is adhered. When the protruding height is 0.5 μm or more, the effect of reducing the amount of static electricity becomes significant. From this point of view, the protruding height is more preferably 1 μm or more, and even more preferably 1.5 μm or more. On the other hand, when the protruding height is 10 μm or less, chipping of the metal oxide particles 50 is suppressed, and failure of the circuit board caused by detached metal oxide particles 50 can be suppressed. From this point of view, the protruding height is more preferably 9 μm or less, and even more preferably 8 μm or less. From the above, the protruding height is more preferably 1 μm or more and 9 μm or less, and even more preferably 1.5 μm or more and 8 μm or less.

[0041] Here, the determination of whether metal oxide particles 50, different from the material forming the exposed portion, adhere to the exposed portion of the main surface of the element body 10 and the determination of the protruding height of the metal oxide particles 50 are performed using the following procedure. First, a release tape is repeatedly applied and removed from the exposed portion of the main surface of the element body 10 of the multilayer ceramic capacitor 100. This removes any fine particles remaining on the exposed portion. Next, carbon is vapor-deposited on the exposed portion to prepare a measurement sample. Next, the carbon-deposited exposed portion of the measurement sample is observed using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS) and multiple backscattered electron detectors. The unevenness of the exposed portion is then analyzed using three-dimensional measurement software. If particulate protrusions are present, the protrusions are determined to be particles adhering to the exposed portion. Next, a compositional analysis of the exposed portion is performed using EDS to obtain a mapping image of the main component elements. Next, if a difference in contrast is confirmed in the adhered particle portion in at least one of the acquired mapping images of each metal element and if it is confirmed from each mapping image that the adhered particle portion contains a metal element and oxygen, it is determined that the adhered particles are metal oxide particles 50 different from the material forming the exposed portion. Next, in the unevenness analysis results for the exposed portion, the difference in height between the lowest point of the boundary between the metal oxide particle 50 adhered to the exposed portion and the main surface of the element body 10 and the highest point of the metal oxide particle 50 is calculated, and this is defined as the protrusion height of the metal oxide particle 50.

[0042] The calculation of the area density, particle size, and percentage of the number of cells in which the metal oxide particles 50 exist, of the total number of cells, of the metal oxide particles 50 adhering to the exposed portions of the main surface of the element body 10 are determined by the following procedures. First, of the mapping images of each metal element obtained by the procedure for determining whether or not the metal oxide particles 50 are adhering, one in which the particulate contrast is most clearly observed is selected, and the mapping image is binarized using image analysis software, after which the particulate regions are counted. This operation may be performed by visually checking the mapping image if the individual particulate regions are clearly distinguishable from one another and are few in number. Next, the number of the obtained particulate regions is calculated based on the area (μm ) of the exposed portion in the mapping image. 2 ) and calculate the area density (particles / μm 2 ) Next, for particulate regions present in the binarized mapping image, image analysis software is used to measure the maximum distance between two different points located on the contour, and this is taken as the particle size of the metal oxide particles 50. Next, as shown in Figure 3, line segments are drawn at intervals equivalent to 20 μm from the left and bottom ends of the mapping image in which the particulate regions have been counted. Next, of the cells divided by the drawn line segments, those whose entirety is located in the exposed portion are counted to determine the total number of cells. Next, of the cells whose entirety is located in the exposed portion, those containing the particulate region are counted to determine the number of cells containing metal oxide particles 50. In this case, if one particulate region exists across multiple adjacent cells, it is counted as being contained in one of the cells. In addition, cells whose sides are less than 20 μm and located at the right and top ends of the mapping image, and the metal oxide particles 50 contained therein, are excluded from the counting. The number of cells in which metal oxide particles 50 exist is divided by the total number of cells and multiplied by 100 to obtain the percentage of the number of cells in which metal oxide particles 50 exist to the total number of cells.

[0043] As described above, the metal oxide particles 50 may be adhered to both or only one of the main surfaces of the element body 10 exposed on the surface of the multilayer ceramic capacitor 100. In the case of a low-profile multilayer ceramic capacitor 100 in which the main surfaces of the element body 10 form the mounting surface 11 and the opposing surface 12 facing thereto, the distance between the mounting surface 11 and the opposing surface 12 is 100 μm or less, and no electrode is disposed on the opposing surface 12, it is preferable that the metal oxide particles 50 are adhered only to the mounting surface 11, as shown in FIG. 4, in order to reduce the element height.

[0044] <Second embodiment> In another embodiment (second embodiment) of the multilayer ceramic capacitor according to the first aspect of the present invention, the internal electrodes are electrically connected to each other by external conductors. An example of a multilayer ceramic capacitor 200 according to the second embodiment is shown in FIG. 5. In the multilayer ceramic capacitor 200, the internal electrodes 22 (22a, 22b) extended to the extension surfaces 13 of the element body 10 are electrically connected to each other by external conductors 60 (60a, 60b), and the external conductors 60 (60a, 60b) are electrically connected to terminal electrodes 40 (40a, 40b) arranged on the mounting surface 11. Note that FIG. 5 shows an example in which the external conductors 60 (60a, 60b) are formed on a pair of opposing extension surfaces 13 and extend around to the opposing surface 12. However, the external conductors may be formed on only one extension surface, or may be formed on the extension surface 13 without extending around to the opposing surface.

[0045] <Third embodiment> In another embodiment (third embodiment) of the multilayer ceramic capacitor according to the first aspect of the present invention, the number of terminal electrodes arranged on the mounting surface is four or more. An example of a multilayer ceramic capacitor 300 according to the third embodiment is shown in FIG. 6. Note that FIG. 6 shows an example in which the number of terminal electrodes 40 arranged on the mounting surface 11 is four, but the number of terminal electrodes arranged on the mounting surface is not limited to this. The multilayer ceramic capacitor 300 has the advantage of being able to suppress the amount of current flowing through the via conductors 23 (23a, 23b) electrically connected to each terminal electrode 40 (40a, 40b), thereby reducing resistance heat generation. In addition, when the polarities of the terminal electrodes 40 (40a, 40b) closest to each other on the mounting surface 11 are different, the directions of the currents flowing through the via conductors 23 (23a, 23b) electrically connected to each terminal electrode 40 (40a, 40b) are opposite to each other. This results in magnetic fields generated by the currents canceling each other out, thereby reducing the equivalent series inductance (ESL). The above-mentioned ESL reduction effect is remarkable when the multilayer ceramic capacitor 300 has two pairs of surfaces that are parallel to the stacking direction of the laminate and face each other, and when the distance between one pair, i.e., the L-direction dimension, is L μm and the distance between the other pair, i.e., the W-direction dimension, is W μm (where L≧W), and the value W / L, which is the ratio of W to L, is 0.8 or more and 1 or less, i.e., when the mounting surface 11 has a shape that is close to a square.

[0046] [Manufacturing method for multilayer ceramic electronic components] The multilayer ceramic capacitor according to the first aspect of the present invention can be manufactured by the procedure described below.

[0047] (A) Preparation of ceramic powder First, ceramic powder is prepared. Commercially available ceramic powders can be used as appropriate. When producing ceramic powder in-house, various raw material powders containing the constituent elements are mixed in a predetermined ratio and pre-fired (calcined). When mixing the various raw material powders in a predetermined ratio, various additives such as the above-mentioned additive elements and sintering aids may be further added, or these various additives may be further added to the powder after calcination.

[0048] (B) Preparation of raw sheets Next, the ceramic powder is mixed with a binder and a dispersion medium to prepare a slurry, and the slurry is formed into a sheet to obtain a green sheet.

[0049] The binder used should be one that can maintain the shape of the green sheet and volatilizes without leaving behind carbon or other residues during the binder removal process prior to firing. Examples of binders that can be used include polyvinyl alcohol, polyvinyl butyral, cellulose, urethane, and vinyl acetate. There are no particular restrictions on the amount of binder used, but since it will be removed in a later process, it is preferable to use as little as possible within the range that achieves the desired formability and shape retention, in order to reduce raw material costs.

[0050] The dispersion medium used is one that does not cause aggregation of the calcined powder and binder and can be easily removed by volatilization or the like after forming into a green sheet, as described below. Examples of the dispersion medium that can be used include water and alcohol-based solvents.

[0051] Components for adjusting the properties of the slurry, such as dispersants, plasticizers, and thickeners, may be added to the slurry.

[0052] The method for mixing the mixed powder with the binder and the dispersion medium is not particularly limited as long as the components are mixed uniformly while preventing the inclusion of impurities. One example is ball mill mixing.

[0053] The prepared slurry can be formed into a sheet to obtain a green sheet by a commonly used method such as a doctor blade method or a die coating method.

[0054] ((C) Formation of internal electrode pattern) Next, an internal electrode pattern containing metal is formed on the green sheet. The internal electrode pattern can be formed by printing or applying an internal electrode paste in a predetermined pattern, or by forming a metal film in a predetermined pattern by vapor deposition or sputtering. The internal electrode pattern is formed with a sufficient margin to ensure electrical insulation with the via conductor patterns that will be formed later and that will not come into contact with the via conductor patterns.

[0055] When forming an internal electrode pattern using an internal electrode paste, the internal electrode paste used is obtained by mixing metal particles and a vehicle in a triple roll mill. The internal electrode paste may contain glass frit and ceramic powder in addition to the above-mentioned components.

[0056] The type and amount of binder and solvent contained in the vehicle used are not limited, and may be selected appropriately taking into consideration the viscosity of the internal electrode paste, ease of handling, compatibility with the green sheet, and the like.

[0057] The internal electrode paste can be printed on the green sheet using, for example, a screen mask on which a predetermined internal electrode pattern is formed. When printing, a space may be left to become a margin when the multilayer ceramic capacitor is completed.

[0058] (D) Preparation of green laminate Next, a predetermined number of green sheets on which the internal electrode patterns have been formed are stacked and the green sheets are pressure-bonded together to obtain a green laminate. The stacking and pressure-bonding can be performed by a conventional method, such as pressing the stacked green sheets together in the stacking direction while heating them, and thermo-compression bonding by the action of a binder.

[0059] During lamination and compression bonding, a green sheet that will become a cover when the multilayer ceramic capacitor is completed may be added to the end portion in the lamination direction. In this case, the green sheet to be added may have the same composition as the green sheet on which the internal electrode pattern is printed, or a different composition. From the viewpoint of making the shrinkage rate during firing uniform, it is preferable that the composition of the green sheet to be added is the same as or similar to the green sheet on which the above-mentioned internal electrode precursor is arranged.

[0060] ((E) Formation of via conductor pattern) When manufacturing the multilayer ceramic capacitor according to the first embodiment, holes are then formed in the green laminate and filled with a conductive paste to form a via conductor pattern. Conventional methods such as drilling or lasers can be used to form the holes. Lasers are preferred because they can produce smooth surfaces. Conventional methods such as syringe injection and metal mask printing can be used to fill the holes with the conductive paste. Metal mask printing is preferred because it is superior in filling small holes. The components of the conductive paste can be the same as those of the internal electrode paste described above, and the amounts of each component can be determined taking into account the hole filling ability.

[0061] ((F) Formation of terminal electrode pattern) Next, a terminal electrode pattern is formed on at least one of the surfaces (mounting surface) perpendicular to the lamination direction of the green laminate. A green sheet, which will serve as a cover when the laminate is completed, may be crimped onto the opposite surface where the terminal electrode pattern is not formed, so as to cover the via conductor pattern. The terminal electrode pattern can be formed by printing or applying a terminal electrode paste, or by forming a metal film by vapor deposition or sputtering. The terminal electrode pattern may be formed using a mask with a predetermined pattern, or by forming a paste film or metal film on the entire mounting surface of the green laminate and then removing the area other than the terminal electrode pattern. Face milling and barrel polishing, etc., can be used to remove the area other than the terminal electrode pattern. When using a terminal electrode paste to form the terminal electrode pattern, the components can be the same as those of the internal electrode paste described above. The blending amounts of each component can be determined so as to obtain a uniform pattern with a predetermined thickness.

[0062] (G) Formation of Metal Oxide or Precursor Particles Next, metal oxide particles or particles of a precursor that will become the metal oxide after firing, as described below, are formed on at least one of the main surfaces of the green laminate. The metal oxide or its precursor particles can be formed by pressing a release sheet dotted with the particles against the main surface of the green laminate to cause the particles to embed into the green laminate, or by printing a paste containing the particles on the main surface of the green laminate. If the main surface of the green laminate is the mounting surface and the metal oxide is an oxide of a metal that forms a terminal electrode pattern, the metal oxide precursor particles can be formed simultaneously during the formation of the terminal electrode pattern in (F) above using a mask on which the terminal electrode pattern and a pattern of metal oxide particles are formed.

[0063] (H) Preparation of pre-fired chips Next, the green laminate is divided into individual pieces to obtain pre-fired chips. For the division, a dicing saw, a laser cutter, or other commonly used means can be used. After dividing the green laminate into individual pieces to form surfaces on which the internal electrode precursors are exposed, the surfaces may be coated with a material for forming margins to obtain pre-fired chips.

[0064] (I) Removal of binder Next, the resulting pre-fired chips are heated to volatilize and remove the binder. The heating conditions can be set appropriately taking into account the volatilization temperature and content of the binder. For example, the chips are held in a nitrogen (N2) atmosphere at a temperature of 200 to 500°C for 5 to 20 hours.

[0065] (J) Firing of pre-fired chips Next, the pre-fired chip from which the binder has been removed is heated to a predetermined temperature and fired. When setting the firing conditions, it is preferable to consider the sinterability of the ceramic powder, as well as the heat resistance and oxidation resistance of the metals contained in the internal electrode pattern, via conductor pattern, and terminal electrode pattern. An example of firing conditions is holding the chip at a temperature of 1100°C to 1400°C for 10 minutes to 2 hours in a reducing atmosphere containing a mixture of nitrogen (N2), hydrogen (H2), and water vapor (H2O). After firing, a reoxidation treatment may be performed in which the chip is held at 600°C to 1000°C in a nitrogen (N2) gas atmosphere or a low-oxygen atmosphere. If metal particles serving as a precursor to a metal oxide are formed in the above step (G), the reoxidation treatment will turn the chip into a metal oxide.

[0066] ((J) Formation of outer conductor and terminal electrode) When manufacturing the multilayer ceramic capacitor according to the second embodiment, the external conductor is formed following the step (J) without performing the step (E), or the external conductor and terminal electrodes are formed following the step (J) without performing the steps (E) and (F). Examples of methods for forming the external conductor and terminal electrodes include a method in which a conductive paste is applied by printing or dipping and then baked, and a method in which a metal film is formed by physical vapor deposition (PVD) such as evaporation.

[0067] The sintered body thus obtained may be used as a multilayer ceramic capacitor as it is, or may be used as a multilayer ceramic capacitor after forming a conductive layer on the surface of the terminal electrode pattern by plating.

[0068] [Circuit board] A circuit board according to a second aspect of the present invention is equipped with the multilayer ceramic capacitor according to the first aspect. This circuit board does not require wide spacing between elements, which is necessary in consideration of the adverse effects that static electricity generated during handling can have on manufacturing efficiency and yield, and therefore can be made smaller and achieve higher performance through high-density mounting.

[0069] This specification also discloses the following techniques.

[0070] (Appendix 1) a laminate in which ceramic layers and internal electrodes mainly composed of metal are alternately stacked; a pair of cover portions disposed at both ends of the laminate in the stacking direction and covering the surface of the laminate; and a margin portion that covers at least a portion of the ends of the ceramic layers and the ends of the internal electrodes in the laminate and connects the pair of cover portions to each other; have Rectangular element bodies, and A plurality of terminal electrodes are disposed at least on the mounting surface, which is the surface that faces the circuit board when mounted on the circuit board, among the surfaces that form the surface of the element body, and are electrically connected to the internal electrodes. Equipped with At least one of the principal surfaces that has the largest area among the surfaces that form the surface of the element body has particles of a metal oxide that is different from the material that forms the exposed portion adhered to the exposed portion. Multilayer ceramic capacitor.

[0071] (Appendix 2) The multilayer ceramic capacitor according to (Appendix 1), wherein the metal oxide is nickel oxide.

[0072] (Appendix 3) The area density of the metal oxide particles in the exposed portion where the metal oxide particles are adhered is 5×10 -5 pieces / μm 2 Over 500 x 10 -4 pieces / μm 2 A multilayer ceramic capacitor according to (Supplementary Note 1) or (Supplementary Note 2), which is as follows:

[0073] (Appendix 4) (Appendix 3) The multilayer ceramic capacitor according to claim 3, wherein, when the exposed portion to which the metal oxide particles are adhered is divided into square cells with sides of 20 μm, the percentage of the number of cells in which the metal oxide particles are present to the total number of cells is 20% or more.

[0074] (Appendix 5) The multilayer ceramic capacitor according to any one of (Appendix 1) to (Appendix 4), wherein the particle diameter of the metal oxide particles is 0.1 μm or more and 10 μm or less.

[0075] (Appendix 6) The multilayer ceramic capacitor according to any one of (Supplementary Note 1) to (Supplementary Note 5), wherein at least one of the metal oxide particles has a protruding height from the main surface of 0.5 μm to 10 μm.

[0076] (Appendix 7) The multilayer ceramic capacitor according to any one of (Appendix 1) to (Appendix 6), wherein the terminal electrode includes a base conductor in contact with the element body and a plating conductor formed on the surface of the base conductor, and the metal element contained in the metal oxide particles is the same as the metal element contained in the base conductor.

[0077] (Appendix 8) the main surfaces are the mounting surface and an opposing surface that is an opposing surface to the mounting surface, The distance between the mounting surface and the opposing surface is 100 μm or less, No electrode is disposed on the opposing surface, the metal oxide particles adhere only to the mounting surface; A multilayer ceramic capacitor according to any one of (Appendix 1) to (Appendix 7).

[0078] (Appendix 9) The multilayer ceramic capacitor according to any one of (Supplementary Note 1) to (Supplementary Note 8), wherein the number of the plurality of terminal electrodes is four or more.

[0079] (Appendix 10) The multilayer ceramic capacitor according to (Appendix 9), wherein each of the plurality of terminal electrodes has a polarity different from that of the other terminal electrode that is closest to the terminal electrode on the mounting surface.

[0080] (Appendix 11) A circuit board having the multilayer ceramic capacitor according to any one of (Supplementary Note 1) to (Supplementary Note 10) mounted thereon. [Industrial Applicability]

[0081] According to the present invention, it is possible to provide a multilayer ceramic capacitor in which the amount of static electricity generated during handling is suppressed. Such a multilayer ceramic capacitor is useful in that it can improve alignment accuracy when mounted on a circuit board, thereby achieving a high yield. Furthermore, the circuit board according to the present invention is useful in that static electricity generated during handling of the multilayer ceramic capacitor has a small adverse effect on manufacturing efficiency and yield, and there is no need to increase the mounting spacing of elements to take this adverse effect into consideration, allowing for miniaturization and high performance through high-density mounting. [Explanation of symbols]

[0082] 100, 200, 300 Multilayer ceramic capacitors 10 Base 11 Mounting surface 12 Opposing Surface 13 Drawer surface 20 laminate 21 ceramic layer 22(22a, 22b) Internal electrode 23(23a, 23b) Via conductor 31 Cover 32 Margin 40(40a, 40b) terminal electrode 41 Undercoat conductor 42 Plated conductor 50 metal oxide particles 60(60a, 60b) Outer conductor

Claims

1. a laminate in which ceramic layers and internal electrodes mainly composed of metal are alternately stacked; a pair of cover portions disposed at both ends of the laminate in the stacking direction and covering the surface of the laminate; and a margin portion that covers at least a portion of the ends of the ceramic layers and the ends of the internal electrodes in the laminate and connects the pair of cover portions to each other; have Rectangular element bodies, and A plurality of terminal electrodes are disposed at least on the mounting surface, which is the surface that faces the circuit board when mounted on the circuit board, among the surfaces that form the surface of the element body, and are electrically connected to the internal electrodes. Equipped with At least one of the principal surfaces having the largest area among the surfaces forming the surface of the element body has particles of a metal oxide different from the material forming the exposed portion adhered to the exposed portion not covered by the terminal electrode. Multilayer ceramic capacitor.

2. 2. The multilayer ceramic capacitor according to claim 1, wherein the metal oxide is nickel oxide.

3. The area density of the metal oxide particles in the exposed portion where the metal oxide particles are adhered is 5×10 －５ pieces / μm ２ Above 500 x 10 －４ pieces / μm ２ 2. The multilayer ceramic capacitor according to claim 1, wherein:

4. 3. The multilayer ceramic capacitor according to claim 2, wherein, when the exposed portion to which the metal oxide particles are adhered is divided into square cells with a side length of 20 μm, the percentage of the number of cells in which the metal oxide particles are present relative to the total number of cells is 20% or more.

5. 2. The multilayer ceramic capacitor according to claim 1, wherein the particle diameter of the metal oxide particles is 0.1 μm or more and 10 μm or less.

6. 2. The multilayer ceramic capacitor according to claim 1, wherein at least one of said metal oxide particles has a protrusion height from said main surface of 0.5 μm or more and 10 μm or less.

7. 2. The multilayer ceramic capacitor according to claim 1, wherein the terminal electrodes include an underlying conductor in contact with the element body and a plating conductor formed on the surface of the underlying conductor, and the metal element contained in the metal oxide particles is the same as the metal element contained in the underlying conductor.

8. the main surfaces are the mounting surface and an opposing surface that is an opposing surface to the mounting surface, The distance between the mounting surface and the opposing surface is 100 μm or less, No electrode is disposed on the opposing surface, the metal oxide particles adhere only to the mounting surface; The multilayer ceramic capacitor according to claim 1 .

9. 2. The multilayer ceramic capacitor according to claim 1, wherein the number of said plurality of terminal electrodes is four or more.

10. 10. The multilayer ceramic capacitor according to claim 9, wherein each of the plurality of terminal electrodes has a polarity different from that of the other terminal electrode that is closest to the terminal electrode on the mounting surface.

11. A circuit board having the multilayer ceramic capacitor according to any one of claims 1 to 10 mounted thereon.

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